SRAM Automatix Review

This is a two-speed hub with coaster brake – it has no cables… the unique selling point is that instead of selecting the gear manually, the hub changes gear based on your speed- automatically!

Β£68 rock solid two-speed hub with coaster brake

Shifts automatically, but absurdly early

After my dismal experience with the Sturmey Archer S2C, which failed dangerously, and having already gone through one terrible S5C hub before that, I decided to branch out in the coaster brake hub gear department, hence this SRAM Automatix review.


The SRAM Automatix offers two gears with a 137% step (that is, it will yield 100″/137″, or 52.5″/ 72″). The unique selling point is that instead of selecting the gear with a shifter, or even by back-pedalling as with the S2C, the hub changes gear based on your speed… automatically!

Again, the attraction of this sort of hub is that you get two gears and a brake with no cables whatsoever. That’s nice for a utility bike, especially as my commute is downhill all one way and uphill the other (so I never found a gear ratio on my old fixed-wheel bike that was decent both ways).

Obviously, the range is far less than you’d get with a single ring and cassette (which could do 30-106″), but that’s ok for me.


At face value the SRAM Automatix is heavy compared with normal hubs, but lighter than some hub gears at 1.3kg.

However, if you add a rear disk rotor (100g), caliper (150g) and lever (80g), plus cassette (330g), shifter (150g) and rear mech (300g) to the weight of an ordinary hub (400g), you’ll get to just under 1.5kg!

The above weights are for Deore and BB7, fairly typical kit. So there’s actually a little bit of weight saving to be had from the Automatix overall (even with rim brakes, not discs) – although you still wouldn’t want it on a performance bike due to the limitation of only having two gears!


As with the S2C, low gear is direct – the internal mechanism locks out, transmitting force on the sprocket directly to the hub shell with no flex or movement. Pretty much as efficient as it gets.

High gear steps up through a simple mechanism and, again as with the S2C, I don’t notice any friction loss when riding it. I’m sure a lab would find plenty, but it’s below my threshold of detection.

I’ve got a couple of busy Strava KOMs sprinting this hub in high gear πŸ™‚


The OLN is 120mm but spacers are provided to make this 130mm out of the box (unlike the S2C, which comes at 116mm with spacers for 120mm).

You can easily add spacers since the threaded axle is bog-standard M10, unlike Sturmey Archer’s obscure only-use-in-the-days-of-Queen-Victoria imperial thread. (In any case, it seems to be routine to squeeze a frame 5mm either way these days). This makes the SRAM Automatix a better choice than the S2C if you’ve got a normal frame rather than a track one.


Again like the S2C, the SRAM Automatix doesn’t have seals over the bearings, so it’s likely to need a lot more attention through winter than your average hub.


The Automatix shift is really nice – quiet and solid even putting a lot of power into the pedals (there’s no way to ease off for the shift as you accellerate). It shifts up regardless of what you’re doing, but it only shifts down if you let off the pressure, so it won’t spill you on a steep climb when your cadence drops.

Unfortunately the shift point is set ludicrously low, at a hair over 10mph. This means it’s almost impossible to get a gear combination that’s useful for actual riding, because as soon as you set off, it shifts up. If you choose a top gear that works out at 60rpm for 10mph, you’ll hit 100rpm at just over 16mph:


The graph shows bands of cadence (red = knee death, amber = OK at a push, green = preferred) across two ranges of speeds (the typical speeds for me, climbing and otherwise). The only one that offers reasonable cadence at climbing speeds doesn’t let you ride around on the flat at all!

On the other hand, imagine if the shift point was around 15mph. Much better, in the amber or green for most of the range (I’ve added a classic 72″ fixed to demonstrate how the Automatix climbs better and allows you to spin along faster on the flat):


Luckily, if you’re willing to get your hands a little dirty, you can make this a reality with minimal hassle…

Adjusting the Automatix shift point

Removing the two left-hand nuts will allow you to remove the mechanism intact (you don’t need to play around with the actual hub mechanism which is controlled by the RHS nuts).

The picture below shows the weights clearly (the big “commas” in the middle!), held in by a spring:

High gear is achieved when the rotation of the hub overcomes the spring, and the weights pivot. I’m holding them open in the photo below, since I couldn’t think of a good way to photograph the hub in motion:
Only one weight has a spring, and the weight itself can be freed easily (it’s held on by a tiny circlip). This image shows the weight half removed, with the spring visible below:
Adjusting the shift point of the hub is as simple as just ‘unwinding’ the spring firmly to give it a different set, then re-assembling.
I found that a change of about 45 degrees in the angle of the ‘arms’ of the spring was enough to lift the shift point from 10 to 15mph, so you’re not trying to unwind it much (although it will take a surprising amount of force to do so).
(Just for illustration – you can see the way the shift works in this image: the weights open out, causing the thin metal plate just above them in the photo to rotate anti-clockwise, adjusting the angle of the pawls visible at ‘9’ and ‘3’ o’ clock).


Stock, the hub is not very useful unless you’re happy to cycle slowly. I wanted my gears around 60″ and 82″ (bracketing the typical single speed of 66-72″) but with this gearing you never get above 60rpm before the upshift, which dumps you at 40rpm!

Climbing a gradual hill was an exercise in agony as my speed would invariably be 10-14mph (the hub never hits a comfortable 80rpm until you’re doing just under 20mph!)

However, now the hub has been tweaked for a sensible shifting point, I can warmly recommend it.

The coaster brake is fine (not as good as the S2C, but fine), but the shifting is worlds better – just so firm and assured, up and down. The auto-shift becomes second nature as you power away…

You also avoid the S2C problem of changing gear every time you brake, which is pretty annoying.

All-in-all, highly recommended!

166 thoughts on “SRAM Automatix Review”

  1. Great review Dave! I’d love to one day get away from an open cassette on my commuter bike so I am always interested to learn about the new internal gear hubs.

  2. FWIW, cut and pasted from SRAM: “This warranty does not apply when the product has been modified.”

  3. It’s easy to argue that adjusting the spring isn’t a material modification (no issues with the hub can arise from adjusting the spring, since it’s just like riding at a different physical speed on the original setting).

    Even if you removed the spring completely from the shell, it would just be like you were always riding > 10mph, which is hardly going to make it explode (I hope!)

    However, FWIW in the UK you’d be covered under the Sale of Goods Act regardless under the fit for purpose clause – SRAM would have to prove that adjusting the spring led to failure and then you could sew them up because a hub adjusted by spring tension can hardly be fit for purpose if spring tension causes failure, can it?

  4. Where did you source a SRAM automatix for Β£68?

    I bought one of these second hand and it lasted a grand total of 12 days before seizing up. It looked slightly out of shape and then once I took the wheel off it pretty much fell apart in my hand.

    It was good while it lasted though, and I would be keen to try again if I could find one again.

  5. There’s a guy who posts on the CTC forum I think, who brings in batches from the states and sells them on. If I can dig out the details from my mail archive I’ll print them up, but you may turn him up checking their forum search?

  6. hiya, shame you can not say adjust the spring tension by adjust a grub screw or something, so the user can set their own shift point without disassembly

  7. I’m with Mark; I’m also a complete newbie regarding anything mechanical. Like you, I’d rather have a higher shift point, and if I can figure this out, I’m set! While I’m here, I’m going to ask another newbie question. Is there any reason why I could not take an old Trek 1000 (road bike frame with a replaceable vertical derailleur hanger) and use it with this hub? Chain tension? Thanks so much for any help/advice you can offer.

    Kind regards,


  8. Hey Willy,

    There are two options:

    -if you don’t want the coaster brake, you can use this hub in any frame with a simple chain tensioner like the Surley Singleator,so that’s no problem
    – if you want the coaster brake, you can’t have a tensioner (same reason you can’t run a chain tensioner on fixed wheels), so you’d need to find a “magic gear”, perhaps using a half link to help get the tension right.

  9. What wheel size are you using it on? If it shifted at 10 mph on 700C wheels, then it would shift even sooner on 406/20″ wheels, right? Some 6-7 mph, I would think. I’m about to test a 406 folding bike with this hub. I wonder if it comes set up for a different shift point straight from the factory, for this application. Time will show.

  10. Hi,

    It should shift sooner on smaller wheels, I haven’t tried this build but it makes sense (smaller circumference = higher RPM at a given speed).

    Would be interesting to know the shift point on the 406mm if you fancy updating us afterwards!

  11. This is marvelous! I used to ride the Torpedo Automatic (made in the 60s, seems to be the very same construction) for some years until the bike got stolen, and I really loved the simpleness combined with the luxury of one climbing gear and one slightly higher to get some speed. For the past few days – on a new bike – I’ve been riding the re-invented SRAM hub and I was just about to switch to fewer teeth (19 to 18 x 46, which I used on the old one, still it switched a little early in my opinion), but this seems to be just what I actually was looking for. I’ll sure give it a try!

    If it works, I can just second your recommendations for this hub. Fwiw, SRAM also makes it freewheel, though I prefer the coaster brake myself.

  12. What a pity the lack of technical information from SRAM, ie a parts diagram, for the Automatix hub on the web.

    I read a post elsewhere on the web giving the impression there are two versions of the Automatix, 28 and 36 spoke, with a key difference in the shift point.

    A parts diagram might give a definitive answer to the question of how this is achieved, are the bobweights lighter in the 28, or is it the spring tension?

    Also can someone please confirm the OLD dimension, I hope it is 120mm, I have not seen anything other than 130mm quoted elsewhere.

    Final point, is it feasible to file or grind away the side or outer face of the bobweight, in theory a reduction will raise the upshift point.

  13. Hi Malcolm,

    Thanks for your comment. The OLN is already given in the review above πŸ™‚

    I’m not sure about the different spoke counts / different shift points. I suppose smaller wheels tend to have fewer spokes, is that the logic?

    You could grind away some of the weight, but that would be permanent, unlike bending the spring.

  14. ” two versions of the Automatix, 28 and 36 spoke, with a key difference in the shift point.”

    I think the 36 hole hub is intended for large wheels and the 28 hole is intended for small wheels 16 to 20 inch rims, which turn at a higher wheel rpm for a given road speed.

    There should to be some internal changes in the shift mechanism to allow the small wheel to reach a decent road speed before the upshift.

    I have ordered a 36 hole hub at a bargain price via Amazon mail order, 28 hole hubs are very hard to find, time to do some experiments with the bobweights!

  15. Bought the 36 spoke, had it fitted – it’s really smooth on the transition and generally opens up for a better range of speeds on my commute with the extra gear.

    However – the swtich point is far too low and being a bit of a novice, it’s difficult to follow how to take the mechanic out of the hub casing to adjust the spring.

    Do you think you could post a video of you doing it on youtube so i can adjust my hub using your instructions?


  16. Hi James,

    I’ll try to find time to YouTube it. Really, you just undo the nut on the brake side of the hub and the whole inner will pull out easily into your hand – you’ll see the circlip and spring clearly.

    I’ll add a link here if I do get around to this.



  17. Great how-to! Question: I failed to see when I disassembled my hub, where does the arm (not the one on the weight) rest in the hub? Is it just against the lower body? I don’t seem to get enough tension to pull the weights in with it there. Thanks,

  18. Hey David,

    Without taking mine apart again I can’t say for sure – it must be fairly obvious as I don’t remember doing anything special.

    I’m 99% sure it doesn’t rest against the hub body. if you let it rotate past the hub body is there nothing to act as an end stop afterwards? I remember winding around the spring before putting the weight back on.

    Sounds like a video might be a good idea..!

  19. I think I figured it out. I should have took some pictures or a video. It rests inside that little plate that where the “comma” weights attach. Those circlips are very small and difficult to put back (especially if you drop them, multiple times). But in the end, I successfully moved the shift point up to about 15 mph. Thanks for the great site!

  20. Hi David,

    Am halfway through this modification – just popped back on here to confirm that I unwind the spring (not wind it further) – should be a doddle from here. Thanks again for this thread, super helpful. Considering how old the mechanic is, it’s surprising that my Cycle Surgery had never seen on of these…!

    All the best,

  21. Hi James,

    Yep, you want to set the spring so it’s unwound a bit. That means you have to use more force to bend it back in place, so it’s pushing against the weight with more force when the hub’s in use. Make sense?

    I think I forced it open about 90 degrees further than standard in the end (after a couple of less adventurous attempts).



  22. Yes, i think mine is now 45degrees back from the starting point, and it appears to shift when I get to 13mph or so – it could do with another shift back so it’s more like 15-16mph. I want to be getting the full length out of that base gear before I’m put into the higher gear.

    Going to do the Dunwich Dynamo next year on this bike, using my 15 mile a day roundtrip commute as a base with forays out of London of increasing distance to supplement the preparations.

    If some chap did 120miles on a Boris Bike, I think it’s more than feasible to use this little two-gear hub on it!


  23. Dave,
    A hudge thank you from Paris for your didactic review
    Thanks to your description I was able to modify the 9km/H shit to 18km/H which fits nicely with my race bike frame with 700 wheels.
    Thanks also to david comments because like him I did not remmeber wher the spring harm rested. You are right it rest inside the plate.

    I have alos a S2C on a VanMoof DÜSENJΓ„GER 28″ (limited edition) , which works nicely but is not as smooth for changing gears.

  24. Hi mccraw
    Thank you for the great automatix review. I have bought the Automatix with Rollerbrakes but i have now problems to understand how to add the spacer to come to an OLD of 130mm. At the moment I would like to use the Automatix without rollerbrakes but with the dust cap.
    The information on the web is not consistent. How do i have to space up.
    What is on the left, and what should be on the right site. Are on the left side 2 times 3mm washers ? Appreciate your feedback to my, i guess, stupid question. Many tanks Ralph

  25. Hi Ralph,

    If I remember correctly, the hub measures 120mm to the locknuts, and yours should have come with two 5mm wide axle nuts that would bring it up to 130.

    One spacer on either side and you should be fine.



  26. I looked around and at least at the moment eBay and Amazon have SRAM Automatix with Coater Brake or without the it and just wondering how complicated is it to remove/disable the coaster brake. As for some reason the Coaster Brake version of SRAM Automatix is slightly cheaper than the one that sports no brake at all. And a hub without a coaster hub is what I am looking for…

  27. Can anyone help me with information regarding ordering the ‘Disc brake’ version of the Automatix hub?
    Tried on looking on Amazon and also on eBay but no luck. Can only find with/without coaster brake only. Any help on where/how to order is greatly appreciated. I’m in the USA.

  28. Marius: I bought a freewheel Automatix just a week ago from eBay. I asked more sellers why they list 980g as a weight, while according to the offical specs (look at the specification tab of that’s the coaster brake version’s weight and the freewheel should have been 780g. Mine weighs in with even more than that (without the sprocet and the bolts are not on it). But I must say that I just measured it with a consumer body weight scale, so I need a better scale.
    My suspicion is what you can deduct from the stock photos of those items. I think (but I still have to confirm) that they are essentially the same, but you just don’t get the coaster brake caliper (or whatever it is called) with it. I was prepared for that (seeing the weight) but still I’m a little disappointed.
    I’ll open it up some weeks from now to perform the shift point modification, and then I can tell more. What I suspect in advance is that I’ll find the brake mechanism under the shiny drum part (which is on the opposite end of the axle than the sprocket). The axle part of the break mechanism well visible on these photos too: that is the part on the opposite end of the axle from the greasy bearing we can see. There must be a matching part on the inner side of the cover drum I believe. I just wonder how easy it is to remove that. Or is it possible at all?
    I don’t want to carry around 0.2+ kg excess weight if I absolutely don’t need it at all. It’s even useless to manufacture and ship it around the world. Waste of resources (both energy and mineral and other). I also own a Sachs Spectro 7, but I was surprised how heavy this hub felt compared to what I expected.
    Let’s share our experiences!

  29. I’m also trying a 16T cog with it, which is reported to be the smallest possible to use. I’ll tell more about this hopefully in a month when I may have time to fiddle with the hub and build it in.

  30. Question: what if someone uses another spring instead of adjusting the existing one? This blog post says there’s only one spring, and I think maybe it is possible to put a spring under the other weight too? I would like to set the shifting point somewhere above 20+mph.

  31. Thanks for your comments Csaba.

    You could certainly put a stronger spring on instead of the stock one. I’m not sure about adding one on the other side. The plate has a notch to accommodate one end of the spring and I can’t remember whether one is present on the non-spring side too (I didn’t photograph it).

    Do post back with your findings!

  32. Thanks Dave. So I bought a kitchen scale, and my instincts were right. The hub weighs ~1180g by itself, and 1280g if I coutn in the sprocket, the screws and washers. That’s very disappointing. It’s not that not 780g, but even 2-300g more than the 980g!
    So I’m 100% sure that the coaster brake mechanism is in, although I still haven’t taken the hub apart. Maybe I’ll send it back. You can find some more pics here:
    I think y’all can identify the coaster brake parts. It seems to be that the “shiny drum” part will be needed, because it hosts that side’s bearing. Looks like there’s a lot of excess bulk towards the center of that part. At the same time, the coaster brake part which goes onto the axle seems to host the freewheel mechanism: the thing which “clicks” or engages sticks out of the drum. This means that I’d be only get rid of the five small shiny metal drums of the coaster brake mechanism??? Really???

  33. My instincts were right. The coaster brake parts are in it except the 5 shiny tiny metal cylinders, which are replaced by a black plastic spacer. That’s one reason it is heavy. Aluminium hub shell? My ass! It’s as heavy as a big paperweight. I want a 780g (real) freewheel version. I’ll put together a small web page about my findings with photos. Please let me know if you know any dealer who can provide me with a better version!

  34. Don’t get me wrong, I’m aware that a gearhubs are not light weight. I own a SPECTRO S7. But an extra half kilogram / 1 pound for no reason? Srsly? Why???

  35. Hi Dave,
    Thanks for the useful post.
    Would you youtube it in a spare time?
    I think it will much more easy to follow each steps.
    Best Regards,

  36. DAVE: thanks for your review and instructions on adjusting shift point. I successfully adjusted the shift point, but being a mechanical disinclined individual, i am worried i reassembled it incorrectly. WHen the hub coasts, it makes a loud “rolling” sound and as it nears stopping, there is a clunky noise (not the normal “clicking” when coasting)…I can feel something “catching” Is this normal? Is this just the bearings being loud? SOrry, I am new at this…..thanks.

  37. tim: anyone else should here would have to take a physical look at it to tell it for sure, but I would double check it. There are two contra nuts on each side. With thightening the “inner” nuts on both sides you basically hold and secure the internals together. You shouldn’t do this too tight however! (But also shouldn’t let it too loose). Then you tighten the outer nuts on top of the inner nuts, this way you secure the position of the inner nuts. (Then comes the dropout, and the lat nut on both sides which tightens the dropouts onto the outer nuts). Also, make sure you lubricate properly: grease those part which needs greasing (the area of the two big bearings on the sides), but only those! The areas which needs oils should be only oiled.

  38. SRAM USA got back to me! Probably what I want (the 780g freewheel version) doesn’t exist. It was offered for big manufactureres but they didn’t order any. Thanks SRAM USA for getting back to me, at least now I see a little more clearly. If I’ll have the hub machined I’ll document it.

  39. Tim, it shouldn’t make any noise like that. It’s important to be sure and tighten correctly as Csaba says.

    The workings of the Automatix are not adjusted by the offside nuts you work on to remove the inner parts (the driveside nuts adjust the tension holding the assembly together, and you won’t have touched those). So, all that can really go wrong is if you don’t tension the offside nut and locknut correctly.

    You could always pop into your local shop and ask them to check the tension for you. There is one near me who always likes a challenge, but just adjusting the tension of one nut shouldn’t be too much for any experienced mechanic.

  40. Thanks guys. Couple of points.
    1. The drive side of my hub has a round spacer and then a single nut. This got loosened when I was loosening the non-drive side nut (I had to hold it otherwise the axle would spin). maybe I did not tighten this enough when I reinstalled. The sound is not very loud, very low pitched, and sounds like the bearings rolling maybe. There is also a small rythemic “jerking” that corresonds with the rolling noise as the hub slows to a standstill. It seems to be “catching” on something, as it goes around.
    2. I have the non-coaster brake hub, so my internals look a little different than pictured above. On the non drive side, I have do not have a circlip on the outside of the round piece holding the plastic “flappers” (dont know what they are called). Instead, I have a round black plastic sleave that fits into the metal piece and overhangs the notches in your picture
    3. I will try and tighten up the drive-side nut a bit when I have the wheel mounted.

    I really wish I could find a service manual with an exploded view of the internals.

    1. Hey Tim,

      You can grip the flats of the axle to prevent it spinning, rather than using the driveside nut (which, as you’ve found, will loosen it).

      Is there any play? It’s also possible that it’s too tight, of course. If I was you I’d get the wheel off the ground (i.e. flip your bike around) when you’re adjusting the tension and see how it rolls freely in the dropout before riding it.

  41. Couple of points.
    1. The drive side of my hub has a round spacer and then a single nut. This got loosened when I was loosening the non-drive side nut (I had to hold it otherwise the axle would spin). maybe I did not tighten this enough when I reinstalled. The sound is not very loud, very low pitched, and sounds like the bearings rolling maybe. There is also a small rythemic “jerking” that corresonds with the rolling noise as the hub slows to a standstill. It seems to be “catching” on something, as it goes around.
    2. I have the non-coaster brake hub, so my internals look a little different than pictured above. On the non drive side, I have do not have a circlip on the outside of the round piece holding the plastic “flappers” (dont know what they are called). Instead, I have a round black plastic sleave that fits into the metal piece and overhangs the notches in your picture
    3. I will try and tighten up the drive-side nut a bit when I have the wheel mounted.

    I really wish I could find a service manual with an exploded view of the internals.

  42. Just wanted to post a follow up. I determined I was hearing/feeling 2 separate things. First, the low-pitch “rumbling”/”rolling” or “thrumbing” sounds occurs when coasting in high gear. I have not been able to eliminate this, but it seems to go away when I start pedaling again. The second thing I determined was the metal plates on the drive side “clacking” and the hub turned. When coasting to a stop, I can hear/feel in the pedals a “clack” “clack” “clack” as the hub nears a stop. If the bike is on the stand, near the end of the rotation as the hub is slowing to a stop, the chain “hops” and the cranks start to spin forward. I eliminated a good deal of this by tightening the drive-side hub nut and when coasting the hub is mostly silent now, but I can still feel the “clack” “clack” being transmitted through the drivetrain. I will try making it tighter tonight to see if that eliminates the issue completely.

  43. Tim: What you describe in your last post sounds strange to me. But we’d have to see really how much it does that.
    Since you have the freewheel version: make sure, that you use non-turn washers, so the hub’s axle cannot turn around, while it is in the dropout! The non turn washer exactly fits the flats of the axle, and the claws will reach into the dropout. I hope I’m clear.

    I’ve learned that the “plastic flippers” are called ratchets. That what clicks when you roll freewheel, and engages when you pedal and propel the drive-train and transfers the motion from the hub-shell to the axle..

  44. I have a crazy idea. If I look at the SRAM i-Motion 3 specifications, I can see that one of it’s planetary gear stage provides exactly the same gear ratio 1.363, as the Automatix. If I’m lucky, that stage part is exactly the same as the Automatix. Furthermore, the i-Motion 3 freewheel and disc-ready hub suspiciously looks like the non-manufactured aluminum hub-shell Automatix freewheel.
    What if I buy an i-Motion 3, and try to fit in the right parts of the Automatix internal mechanism into it?

  45. Thanks for this review.
    I want to buy a SRAM automatix for my kid’s bike, which will have 18″ wheels.
    I guess I need a 28hole version (I haven’t counted the spokes, because I don’t have the bike yet … it will be this one: )
    My questions: at what speed do you think it will change gears? Do you think is appropriate for a 4 years old, tall boy for his age, to make the modifications you presented?

  46. You can calculate the approximate shift point mathematically. The shift is triggered by the rotation of the tires. If the hub shift at 11mph with 27″ wheels, then you can calculate the rpm of the wheel, and then deduct what that means for 18″. I can do the calculation later here if needed.

  47. Hint: the smaller the wheel the smaller speed the shift point willbe at. The speed with a given rpm is proportional to the circumference of the wheel, which is proportional to the diameter of the wheel: 2*r*pi=d*pi. d=diameter, r=radius. Let’s say that the the shifting point speed is s=11mph. The smaller wheel with the same rotation goes 18″/27″ slower. So the shift point is modified by 18/27. If the shift point is 11mph with the larger wheel, it’ll be 11*18/27 with the smaller wheel, hence 7.333 mph. General eqution: s_l = large wheel shift speed, s_s = small wheel shift speed, d_l = large wheel diameter, d_s = small wheel diameter. Equation: s_s = s_l * d_s / d_l. Note, that I didn’t calculate with the thicknes of the tires, that can make some difference, if the child tire is 1 inch fattier than the large tire.

  48. Thanks, Chaba!
    Ok, so the speed for shifting gears will be 7-8 mph, let’s say.
    I’m more interested in how appropriate is for a 4 years old boy who loves cycling to have the gear shifted at this speed. Will it be comfortable for his knees? It is the graphs in the review that wary me (especially that “knee death” atribute πŸ™‚ ).
    Not only that I’m mechanically illiterate, but also I’m not much into cycling. That’s why I don’t understand exactly all this calculus about gears, but I’d love to know more about the graphs presented in the review. What exactly is designated on the ox and oy axes?

  49. Alex, it will be fine for a four year old – most of them don’t have gears at all!

    Unless you spend many hours riding the knees are not in jeopardy, so I really doubt you need to worry there πŸ™‚

  50. Thanks for reassuring me!
    As I’ve told you, he loves to ride and we ride 2-3 hours/day during weekends.
    Now, the big problem is to find a 28holes version of this hub online.
    I’m from Romania – Romanian bike parts dealers don’t have the automatix (36 or 28), on there’s only the 36h available ….

  51. I’d go for a 36h 18″ rim and wheel build – keep the original wheel as it is (even if only so you can sell the bike complete in a few years without having to sell the Automatix too)?

  52. AlexC: the german review basically says that he experienced wear signs much sooner than Shimano internal gear hubs. I don’t have any usage experience yet, since I may make bigger modification of the hub :). The German disappointed reviewer also says, that the shifting can be triggered also by potholes. And also claims that the shift from nd gear to first gear requires stop pedaling for a blink. I’m not surprised about these, I think the shifting back not always requires stop pedaling, but I wonder what the current users with expreince tell about that.
    I spoke with some persons in my home country about the hub, and one of them fall for the Sturmey Archer S2 Duomatic. He disassembled it and he claims that it looks more robust than the Automatix. Which sound a little unreal to me, since the automatix itself looks pretty robust. But I have to see it by myself how much the hub will take.
    Duomatic is a kick-back shifter, and I also read more reviews which were about unusually early wear, and also abrupt shifting in case of rolling over rails and stuff.

    For sure what you can expect with any gearhub: there are very few shops which can repair them or even know them.

  53. What a spring trick! I can’t believe I succeeded in doing it…

    Two weeks ago I bought a Nishiki-bike with this hub. Being a large man i was somewhat disappointed for the hard work that moving consisted from me. First I changed the sprocket from 21-teeth to 22-teeth, and that helped a bit. But, it did nothing to the early shifting.

    Then I found this blog. I’m happy I had the guts to try the trick. I lost both the spring and the weight at leat two times, Add I did not remember how the spring assembled before taking them off…

    Nevertheless, after just testing the bike, I’m really happy, it’s a even a newer bike now… I was laughing in a cold windy rain… Thank you really for the trick, how did you ever came into it?

    -iikka from Oulu, Finland

  54. Hello gang.

    I roll both Sram and SA 2 speed, the Sram mounted a 24″ rim with a 3″ tire and 22tx44t (cruiser). The SA mounted on a 700c 23tx46t (city bike). I roll 200km a week and not a speed freak, just enjoying not being stopped in the clugged traffic. I just love both hubs, they do shift when hitting bumbs and whatever other ppls complain about those 2. When you know how the internals work you become a bit more comprehensive. Both are robust and reliable, SA do brake well and shifting is sometime not precise but your learn to cope, and forget riding in winter without changing he grease. The Sram is the free wheel ver (Cesur do make a disk adapter for it), automatic is cool as my cruiser but I do like having the control of when I shift.

  55. Hello!

    I’ve been intrigued by these two speed hubs as a consequence of my drivetrain(s) being absolutely destroyed by my commute these past two winters. I want to build up a bike that is nearly impervious to bad weather, so I was a bit disappointed to read that the S2C and Automatix are equally poorly sealed.

    It didn’t make sense to me that these hubs would be ill equipped for rough weather usage, as it seems like such an obvious application for this type of design. I decided to turn to the manufacturers themselves and see what they had to say.

    Sturmey Archer responded with disappointing news: they told me flat out that they do not recommend the S2C for “very bad weather” and strongly recommend flushing out the grease and replacing it “every couple of months” if it’s being used in such conditions.

    SRAM, on the other hand, provided a reassuring response! They told me that the recommended service interval is every 2 years or 5,000km . . . much more relaxed. They also shared this anecdote:

    “We have employees riding this hub in both our Chicago and Germany locations, both of which have their fair share of weather from blizzardly cold to rainy summers. Keeping the unit clean, especially from winter salt, will keep the hub performing optimally.”

    Furthermore, the user manual for the Automatix has the following to say:

    “Your rear wheel hub is well protected against adverse environmental effects.
    Β» The rear wheel hub is not completely waterproof. However, do not use water under pressure (such as pressure washers or water jets) for cleaning to prevent malfunctions due to water penetration.
    Β» Do not use agressive cleaners.
    Β» During the winter season, you should clean your bicycle in shorter intervals so that winter road salt cannot cause any damage.”

    That all sounds pretty good to me; it’s consistent with the advice you’d be given for any hub with a labyrinth or double contact seal, really, which are about as “sealed” as you can ask for.

    Wiping the drivetrain down routinely is a perfectly reasonable expectation that I can live. Repacking the hub every month or two? Not so much.

    Can you chime in on this, Dave? Is it possible that you underestimated the way the Automatix is sealed?

  56. Hi, I just got the Sram Automatix w coaster brake and 36 holes. It came with a 19 tooth sprocket. What size front chain ring would be appropriate? I am building it with 700c wheels for a commuter for short rides in poor conditions. I am a decent cyclist but likes to spin light gears. Grateful for any input.

  57. Hey Peter, 42 on the easy side and 44 for a bit more torque. Changing the rear cog is as cheap as it comes, at $5 a piece you can buy like 3 different ones and test ride, fairly easy to change too. Just make sure the retaining clip is well seated.

  58. @Biggus: thanks for sharing your experiences with both 2 speed hubs.
    @Carl: I’ve spoken with a bike shop employee, who weren’t satisfied totally with the seals. If you simply hold the hub without the protector plate, the bearings are kind of exposed. I don’t know how much the protector can do in rough conditions.
    step A. Take an existing bike where you like the resistance.
    step B. Compute how much distance the bike goes ahead by one pedal turn. This can be measured or computed.
    step C. Take that number and then do the reverse computation, and you’ll end up with the numbers you need.
    There are 3 main variables in the equation:
    1. wheel size or circumerence
    2. chainring teeth
    3. rear cog teeth
    You can find a ton of on-line sites which help in these calculations. Beware, because replacing chainring maybe not trivial, and maybe not cheap. You have to be aware the BCD of your crank arm. You need to adjust the chain too. So rather do the calculations first and try to end up with the good number right away.

  59. So, I tried this fix and failed, miserably. The bike no longer shifts gears. It’s in the shop now. PLEASE HELP, lol. I need to know how to set the spring back in so it operates properly.

    1. Hi Nick,

      I’m guessing that you’re sorted now, but if not, drop me another reply.

      Providing you didn’t lose any of the parts, it’s not hard to put back together and I can explain.



  60. Just tried this trick these days. It took a while to figure out how the spring assembled, but it works.
    Although, I found it rather difficult to tighten the hub properly. No matter what I do its either too tight or too loose. When I just had the right tightness off the wheel, as soon as I put it back on and tighten the outermost/axle nuts, it tightens the hub even further. I find this strange. I’m not using and washers since they didn’t come with the bike/ the stock wheel, and the have the same measurements – so I’m guessing I shouldn’t put any on.
    Finally, after hours of tweaking and testing I found a tightness that works, so the wheel is properly secured, and the hubs isn’t too tight, although a bit tighter than I would like.
    Any tips regarding this would be appreciated!

    @Nick: Read Davids posts in this thread. He had the same problem and fixed it. His post helped me at least.


    1. Hi Simon,

      It’s just one of these things, like when you set bearing tightness for a QR skewer wheel (only less so, as the effect isn’t the same with a threaded axle).

      Glad to hear you found it by trial and error – that’s my way too πŸ™‚

  61. Hey,

    @Csaba Toth – I want to remove the braking action when I pedal back (I got a front brake). I understand from your excellent investigation that the freewheel black plastic replaces the metal cylinders that do the braking. But would you say the black plastic is essential? What do you think would happen if I just removed the metal cylinders?

  62. @Martin: I think that it is probably needed (why they wouldn’t leave it out otherwise?). If you look at the photos carefully again, the cylinders don’t slide all along into the gaps, but they “stick out” by apprximately 2 mm. Now if you look at the black spacer part, it has 2 mm rims, which mimick this distance. Without that the copper color component may slide 2 mm towards the part I marked 5. But I think if you find any kind of spacer solution which holds this distance in a reliable way and don’t interfere with other components, you probably good to go.

  63. @Martin: Clarification: so the cylinders stick out 2 mms along the axis towards the component I numbered 5. The rim I’m taling about is also at that location (the black spacer has all kinds of rims).

  64. @Csaba Toth – Thanks! Indeed the component looks important. Perhaps a job for those new 3D printers I’ve been reading about πŸ™‚

  65. @Carl – sorry for the late response, I’ve been moving house and my ISP couldn’t seem to get their act together (2 weeks to set up line plus a further 10 days to activate – unbelievable!)

    The Automatix is poorly sealed IMO, but on reflection mine still hasn’t packed in after around 18 months of daily use (now doing a minimum of 20 miles a day), so perhaps it’s not as big a problem as one might believe.

    That said, it doesn’t run as freely as my other hubs, so YMMV as far as what acceptable performance is?

  66. Hi,

    I have one of these, and it was a bit crunchy and grindy. I took it apart and smeared copper grease on the bearings, then did the fix you described above – and it’s still really grindy. I am not terribly mechanical, and it almost looks like there is a missing bit for the bearings to roll round. I might just be misunderstanding how it works.. My local bike shop (Phil Corley) don’t do servicing of this hub apparently.

    Did yours ever do anything like this?



  67. Hi Dave
    Thanks for your post
    I have the same question as Peter E-J from a couple of months ago, I can’t see a reply (sorry if you’ve already replied)
    I have just purchased this hub, with coaster brake, and as Peter said, a 19 tooth sprocket…..I am searching the net to find a recommended front chain ring size, what did u have?, and what would u recommend?

  68. Hi Ben,

    A 42t ring with 19t sprocket would give you 58″ and 82″ (usually a fixed wheel is ridden around 72″, so you would be able to go a bit faster but also climb steeper hills).

    Depends on your terrain really. If it’s flat, you could go a bit higher, if it’s hilly lower (racing bikes tend to be from 35-40″ at the low end to 110″ at the top)

  69. Thaks Dave
    Just what i needed to know, and thanks for prompt reply
    (I can get a 44t chainring, so that should be perfect)

  70. Hi Dave,
    just tried this last night and it looked ok (also had the issue of overtightening the left-hand-side nuts when reassembling, resulting in high friction, but found that out myself…). However, today the hub appeared “locked” in the high gear and did not shift at all. Have I reassembled spring and weight incorrectly? Do I need to “fit” the spring in some crevice or whatever of the weight?

    May open it up again tonight and see what I can do… πŸ˜‰


  71. It sounds like perhaps you haven’t hooked the spring in correctly, as if there is no spring action, the hub will pretty much default to high gear (nothing to make it switch down) which matches the symptoms you describe.

  72. Thanks! I knew I should have checked more thoroughly how the thing looked in assembled form.
    Will try again tonight.

  73. Obviously I am quite dense but I too think I have the spring loaded back in wrong. Can someone describe in some detail how the spring is supposed to go back in. Does it go through the slot in thin metal plate or remain above it?

  74. I have a question and an observation. First, my question is that my hub axle has developed an annoying propensity of becoming “locked” to the locknuts. In other words, when I tighten the locknuts, the whole axle moves with it, which results in the hub overtightening. I cant figure out why this is happening.

    Next, my observation. People experiencing a lot of noise with their hubs should check to make sure the ball bearing clip is in its proper recess. Upon taking my hub apart, I noticed that my non-drive side ball bearing clip had worked itself out of position (which is what presumably was causing all the noise)

  75. @those who can’t figure out how to put the spring back on.

    It’s a bit tricky to put the spring back on, if you didn’t pay enough attention to how it looked in assembled form.
    I just had mine apart again to set the shift-point a bit higher, so while I have it fresh in memory I made this sketch in Paint (bear with me). Follow the link, and you should be able to mount the spring back correctly.

    Hope it makes sense…

  76. I’m lucky to live in a city with great weather and a long flat bike path which runs very near to my home. I can ride this path almost all of the four miles to my job downtown. So I bought an inexpensive large-framed single-speed bike with 700c wheels and found my commute to-and-from the office to be quite easy. The bike path sections are about a half-mile long between street crossings and the bike is geared low enough (38/19) to make those street crossings easy. The problem was about halfway down that half-mile block, I was running out of steam and wishing for a higher gear. My bike frame has no lugs for routing cables, so the SRAM 2-speed Automatix hub seemed like a good solution. When I read the web reviews everything sounded great, except the many complaints about the early shifting at too low of a speed. Even so, I liked the idea of this hub and wanted to take a chance, even if I wound up having to do some tuning of the spring tension. So I bought the hub off the web and took it to my local bike shop to have the rear wheel rebuilt. They had to order new spokes and the turnaround with labor took about a week and cost as much as the hub. The shop guy said it tested well for him, so I took it out for a few test rides. I don’t know – but I assume – that wheel size makes a difference, as the shift point is controlled by the centrifugal force created by the rotational speed of the hub. If so, it seems as if the hub I received was very well tuned for a 700c wheel, as it DOES NOT shift too early for me. In fact, I have to crank my pedals pretty hard to activate the shift. By that time, this 57 year-old is getting a little winded. I wish it shifted about one or two MPH lower, but not enough to risk screwing up a perfectly nice working hub with my mediocre mechanical skills. I think this hub probably shifts way too early on a small-wheeled folding bike, but for a full-sized bike with 700c wheels, it seems to be tuned just about right.

  77. Durability?

    I just got a bike with the SRAM Automatix two speed hub, and i was wondering about the durability of the hub? Can’t seem to find that in any rewievs.
    I use my bike for everyday transportation, so i need to rely on it not breaking down. I ride about 10-15 km every day. I live in a flat city, so i don’t ride very fast or hard. Will the SRAM Automatix hub stay alive without much maintenance?

  78. I build a wheel with 700x25c tire yesterday and rode it 30 km today. The shifting point was at 18-19 km/h. I dit the modification and now the shifting point is at 24-25 km/h witch corrospond to some 99 pedal rpm just before shifting. The gearing is 38/19. It seems right here in the flat and windy Copenhagen.
    The axel tread is 10x1mm, I got wrong nuts 10,5x…
    Thanks for the review and modification tip.

  79. Has anyone “daisy chained” more then one of these together in a frame mounted mid-transmission set-up? I build my own frames from welded steel (mainly 304 stainless) so I can build the frame to accommodate any transmission set-up I desire. I was thinking of putting an S&H fixed three speed hub inside of a 20 wheel build and then run a short chain up to one of these mounted in the frame with a trike gear box type output sprocket bolted to the hub-flange and then stack another one of these right in front of it and do the same thing and then finally up to the crank. Adjust the springs inside them to make the shift points just right for my style (one closest to the wheel shifts first at about 80-ish RPM pedal cadence and then the second one shifts next at about 100-ish RPM pedal cadence after I spool back up after the first shift). That set-up would give me three automatic gears with an “all up” 188% total range in two 37% up steps and then in the actual rear wheel hub (so it doesn’t effect the shift points) the S&A fixed gear three speed that is an “all down” 160% range in a 33% and a 20% down shift. Three manual gears and three automatic, I can manually shift down for big hills and have a wide range three speed automatic shifts for accelerating in traffic when the light turns green or other situations where I need the automatic shifts to take care of themselves during acceleration so I don’t have to think about them (and the first of those two shift points is kept shifted up even if I coast for a moment due to running off the fixed hub in the rear wheel) and a total range of 300% with both the manual and automatic gears, more then enough for almost anything short of heavy cargo hauling or deep backwoods mountain biking.

    Just wondering if anyone has already done anything close to this. Specifically, either daisy chaining more then one of these together to get more then just two automatic gears and/or using one or more of them as a frame mounted mid-transmission.

    Also, can’t seem to find any specs. in my online searches as far as how much torque these things can take. I’ve personally disemboweled a few of the weaker IGHs due to putting to low of a gearing ratio on them in terms of crank chain-wheel size vs. hub drive sprocket size and then start “jamming it” on a hard acceleration or hill climb and end up shredding the hubs guts. So I do like to have rated torque specs. I can check something I haven’t been able to find for this hub. Any information on that would be appreciated as well. Gearing up a lot on the first stage from the crank to the mid-transmission mounted hub(s) like a 52t on the crank back to the smallest tooth count I can get to fit the hub in question and then gearing back down after the mid-transmission to the wheel (big sprocket on the wheel I can get to fit or even have custom made to fit and the smallest output sprocket I can on the hub-flange) seems to have solved that problem in most cases but if I have the specs. I can run the math and see how far I have to push that to keep the torque within the hubs limits, some can take a lot more then others.

    Any helpful comments, info, etc . . . appreciated.

    1. Hi,

      I don’t think this will work as the hub shifts based on the rotation speed of the shell and not the sprocket RPM (otherwise the shift point would change depending on your sprocket size). If you can spin the whole hub shell it should work, but I’m not sure quite how…

      In terms of robustness, I had much better luck with the Automatix than other hub gears, but mine has now failed (keep meaning to update this article, actually).

      Not unhappy given my mileage and the low cost of the hub (around Β£60 when a new chain can be Β£10-15 at the LBS), but I wouldn’t take it wilderness touring or anything!

  80. FYI: For anyone that is having problems with the cones tightening, the anti-rotation washers that come with the hub don’t seem to work. You need to get the kind with the tabs that are squared in the drop ends of the frame….otherwise whenever you tighten the hub onto the frame, the axle will rotation and the cones will tighten.

  81. Hi

    I’ve had mine apart once again to change the shiftpoint (is it just me, or do the spring “wear out” a little bit, and changing earlier?) – and ended up unwinding it out of shape. So, just for the fun of it, I tried with a spring from a regular pen. It seemed stronger/ more tight than the original, and so far it works really well and shifts even later than before. I’ll come back with an update on that if it fails later on…

    Sadly though, since I’ve had it apart again, it has started making a rattling sound when in freewheel, and a slight grinding noise when pedaling, which I can’t seem to eliminate. I’m pretty sure it isn’t the new spring making the noise, since I’ve installed that, and the noise continued.
    I’ve notice the hub has gotten quite dirty, especially bearings and brake shoes (after aprox. a years use) – any guess on wether I could eliminate the sound by regreasing the whole thing?

    Someone here: eliminated some rattling by swapping out the “O-ring” with another one. Dunno if I should go for that – but I have absolutely no idea how to get at hold of another one.

    Any insights would be valuable !

    Also, I’d like to hear how yours failed, Dave? If you could update the article when you got time for it, I would greatly appreciate it πŸ™‚


  82. *I’m pretty sure it isn’t the new spring making the noise, since I’ve installed the old one again, and the noise continued.

  83. Hello there… is there a fixed gear version of this hub? Or is it possible / safe to convert it to fixed gear?


  84. Thanks so much for posting this! I managed to tune my Automatix just like you instructed. I had to bend the spring back close to 90 degrees though, instead of 45 to get it to shift at about 16mph.

  85. Just laced an Automatix on a 700 rim with a 35 tire. It shifts at 12.5 Mph at factory setting. Wich is just fine on my Diadora Elettrico (pedelec). The bike came with a 7 speed wheel and was a bit awkward to operate. Using 16t-44t is just perfect with the wheel size. When I hit 20 Mph, the front engine wheel become a free wheel and Im on my own. Love the hub.

  86. TMB: thanks for the advice. Those anti-rotation washers are also called non-turn washers, and I cannot imagine how could they really work without the claws which square into the dropouts. This will be important for me soon, because I gonna put one of these into a titanium frame. Those washers wouldn’t able to bite into the titanium at all, so the only thing which can prevent them from turning is the square in what you describe. I don’t know why they don’t have those on the washers, maybe I’ll need to order some. The secure seating of the axle is very important for the internals of the hub.

  87. Also, one person drew my attention to there are some silver and black disc version of the hub listed right now. Those hubs looks like to have aluminum shell. Hopefully they will be the 980g factory spec, as opposed to the steel freewheel version’s 1170g (vs 780g on SRAM website).

  88. turbo1889: You are thinking in pedaling RPM, but the hub shift regarding the wheel RPM. That’s the thing you should keep in mind! Usually the wheel RPM is a lot higher 2x-3x-4x than the pedal RPM. Once you keep in mind this, you can plan your setup. With the finding of the article here you can adjust the shifting points in your hubs. You have to model the system, am I understand correctly that you want to use 3 hubs together (2 automatix and 1 SA 3 speed)? The most important simulation would be about what’s gonna happen at the various shifting points. How would the whole system react, would other hubs than you want trigger shifting?

  89. Hey, this site is a great help.
    Csaba Toth, thanks for the info about false marketing considering the weight of the hub. I myself was planing to assemble light bike based on automatix and unfortunately already bought the heavy one but I could return it If I would find the alluminium version. Do you now enything more abot the weight of the
    one sold on Enyway even if its for disk brake, could it be instaled without one, as a freewheel?

  90. Hi Dave,

    Do you know the spokes size?
    I will like to install it on a Worksman, the spokes I have on the bike are 11G.

    Thank you in advance for your answer.

  91. I’m going to convert one of my bikes to use the Automatix. I can’t find a local wheel builder, so what size spokes would I need for this hub with both 26″ and 700c wheels?


  92. Hello Dave, forgot to subscribe so only just saw your answer. Can’t get the link to work though.
    I’ve ordered a Automatix freewheel hub from Amazon for Β£52. I nearly ordered it the day before when it was 70 quid!

  93. Thanks Dave for this super-helpful post and thanks all (esp. Csaba) for the comments. My goal is the same as Csaba’s: get a 780g Automatix and modify it to shift at ~20mph on 700c wheels. Has anybody found the 780g Automatix or confirmed Csaba’s findings that it’s unavailable?

    @Dave: I second Simonfromdk’s request, would be cool to read an update on how yours failed and if you bought another one.

  94. Hi Dave,
    thank you for that review if been looking for a way to change the setting of that hub for a long time for my customers (DIY-workshop for bikes) despite the fact that i`m pleased with the way mine works (19-46).
    I’ve got a suggestion for people that consider to buy this hub – its avaible in two versions first there is the reviewed one for 26″ to 28″ inch wheels but they also sell anotherone for 20″ to 24″ inch wheels and SRAM claimes that both shift at the same speed.
    That could be a way to go around the whole spring adjustment process because put diffferent springs inside anyway. The small wheels turn faster at the same speed and so it could be perfect for a big wheel.
    If anyone is interested in one of these leave a reply.
    IF anyone tried that out already – how is it working?
    Best regards

    info (at)

  95. Dave, sorry I forgot to update you on the small wheeled bike (406/20″). I did buy it (Tern Verge Duo) and it shifts at 15 km/h (9.3 mph). So it seems to have a different spring than yours. The gearing is 46/18, and my cadence drops from 64 to 46 as it shifts up. 77 at 25 km/h.

    This should mean knee death, but I’m really happy with it. Though I average 78-82 cadence when riding my recumbent, I was happily doing 16-20 km/h averages on the little folder during my last tour, meaning average cadence of 49-62, not counting the first gear. I’m cruising the flats at 23-25 km/h which is perfectly fine for my knees. When climbing I often wish it would shift a little later though, and I avoid hilly terrain. But I think 20 km/h (85 to 62 rpm) would be too late, so 17-18 km/h should do it. (Maybe it’s bad technique, but I can’t do very high cadence on uprights. Mostly I stay well below 90. On the recumbent I’m happy at 90-100 on high intensity. Same crank length.)

    The shift point is great for one thing: Sprinting off from a traffic light. The drop to 46 cadence is just perfect for me when standing and cranking hard.

    1. Thanks for the update Gunnstein. It’s a pity that the hub shell itself (or perhaps the axle) doesn’t expose something like a little grub screw that allows the shift point to be trimmed – it would be so easy! Glad to hear you’re relatively happy though πŸ™‚


  96. Yep, that would be very handy. Anyway, I like it enough to consider it for a second bike, a snow-capable commuter. Crazy wish for SRAM: Expand it to a 3-speed!

  97. Hey guys,
    I’m thinking of going for the coaster brake version of this. Basically to lose all rear cables.
    Can anybody recommend a front wheel hub to match the rear? possibly a drum brake. Do Sram produce these? sorry if this has been asked/answered already and I have missed.
    thanks, Kenny

  98. Spiff: If you measure the diameter and width of the spline that is used for the circlip you should be able to buy the correct size.

    Greetings Ramon

  99. Hi
    Does anyone know the 20-inch version’s Sram part code of this automatix with coasted brake? I have a folding bike and want to make sure I would buy the correct smaller wheel version.
    Many thanks

  100. Hi from France
    Thanks Dave for this very helpful review and thanks for all the contributors.

    I just mounted a black anodized free wheel disc version of the hub on a 20″/206 rim with Schwalbe Kojak tire. The freewheel is a bit noisy but pedaling and shifting are silent.

    FYI, this hub version weighs 890 g (~19.6 lbs).

    According to my speedmeter, my hub shifts at ~12 km/h (7.45 mph), after a first mod of the spring, now it shifts at 16 km/h (~10 mph), I’m planning to push it to shifts at 18~20 km/h (~12 mph).

  101. awesome website- very good. I have hacked my hub as above, – but have 2 questions/concerns-

    1- when re-assembling I may have damaged the plastic spacer which comes in the freewheel version. Does anyone have a photo of a good condition sopacer which shows the 5 ( ithink) clip parts? I justw ant to compare it to mine.
    2- Does anyone know if the hub has 1mm or so play side to side and if it can be eliminated? I ‘ve tried both loosening & tightening the lock nuts on each side (separately). If i get the play out of the hub, it does not spin very well at all. If it spins well, then I have the play, and cannot find an acceptable medium!

    Cheers in advance, and thanks again for the instructions!

  102. I recently bought and installed an automatix 36 hole with a coaster brake on my 26″ beach cruiser. I used a 44 tooth Front Sprocket and switched to a 21 tooth in the back. I like the shift point so far. The problem I’m having is with the coaster brake squealing. The arm is attached securely to the frame but the thing squeals and kinda vibrates when I brake. Any suggestions?

  103. Brian, mine was silent and working well for about 2 years, then started behaving as you describe. I took it to a bike shop, they lubricated it, twice, and then it was ok. It’s strange that you should have this problem on a new hub, but the solution is probably lubrication. It must be the right kind, I believe they use a special grease intended for coaster brakes. (It sounds strange to grease a brake, but it’s correct for coaster brakes.)

  104. Dear All,
    I would like to make a request/suggestion. Can somebody post the “Part number” for each variants of the automatix hub please with a short description including switching speed? Somebody mentioned above that 2 variants exist (for 26β€³ to 28β€³ and 20β€³ to 24β€³ wheels). After some searching I am guessing that the smaller 28h is 20″ to 24″ wheels and the 36h is for 26″ to 28″.
    can somebody confirm the above please?

  105. hi
    shifting point is always 15 or 18km/h depending on the wheelsize
    but as i said befor if you use a 20/24 hub and put ist in a 26/28 rim it shifts later

    26″/28″, 36 holes silver coasterbrake 120/130mm

    26″/28″, 36 holes silver no brake 120/130mm

    26″/28″, 36 holes silver for shimano rollerbrake 120/130mm

    26″/28″, 32 holes silver , for discbrake with 6 holes 135 mm

    26″/28″, 32 holes black, for discbrake with 6 holes 135 mm

    20″/24″, 28 holes silver coasterbrake 120/130mm

    20″/24″, 28 holes silver no brake 120/130mm

    75€ – 95€

  106. @Mathias, thank you so much for your post. It is very valuable.

    One question; as you mentioned the shifting point is 15-18km/h on all versions as long as the defined wheel size is used. Therefore these two 20-24″ versions (01.0200.001.020=20β€³/24β€³, 28 holes silver coasterbrake 120/130mm AND 02.0200.001.020=20β€³/24β€³, 28 holes silver no brake 120/130mm) use a different spring compared to the 26-28″ versions. Therefore, we can safely say that those who want 15-18km/h shift on a 20in size folding bike should select any of those two is they want to avoid adjustments, right?

  107. @mz/x Right. For the record, I have the unmodified 28 hole coaster brake version in a 406/20″ wheel, and it shifts at 15 km/h, quite exactly.

  108. Gunnstein, thank you for confirming my suspected scenario. Now I know that for my folding with 20″ wheel which model would work best. It’s shame that the 20in version does not come in black. πŸ™ Or, is the 20-24″ with 28h available in black?

    On the other hand, this is a useful info because those who want to mod their 26-28″ versions should simply order the spring of the 20-24″ version. (Depending on availability) This will predictably increase km/h shifting point for larger wheel size. (As a result some fiddling tests can be avoided.)

  109. I have no idea about a black version, but you can of course do as I do, just don’t wash it and it’ll become black soon enough πŸ™‚

  110. Just a follow up to my previous questions that I *think* may be solved. I have played again with the LHS locknuts and got the wheel spinning very nicely with little/no play.

    I cannot however remove the friction from the drive side. The crank itself spins nicely without the chain on it. When its all assembled with chain etc, there is a lot of friction both forward or back pedaling.

    Is the cog supposed to be able to spin freely in reverse (like a normal freewheel) or pedaling forwards- and if so- would that tension be controlled by the drive side lock nut either loosening or tightening?

    If not does anyone have a suggestion as to what would need to be tweaked to remove this high drive side friction which is sapping my legs at the moment?

  111. hi
    have just attempted to unwind the shift spring on my sram automatix 2 speed hub but when reassembled it starts off and stays in high/top gear all the time. i cant see where or what the spring tension is against is it up or down (trying to push the weight up to circlip ) or is it to stop it flapping on post, where does the botton /tail of spring go on top of loose plate or below loose plate. hope you can help
    thanks clive

  112. @clive- i had the same issue. It may be a case that when re-assembling you have not wound the spring right around to force the weight back into the closed position.

    Following up on my last post- I have sorted the hub after some tinkering. Turns out I was a numpty and had put the plastic spacer back in the wrong way- causing the friction. I’m unsure actually how i put it on backwards but I did… That side of things is all good again now that I’ve reassembled correctly.

    Regarding the spring- I got rid of the SRAM spring, and got a spring out of a click pen. Unwind 2-3 coils and cut it so there’s approx 3 or 4 full turns plus the straight section either way. Fit this back in to the hub, hooking one end into the groove and the other end folds back/around so it’s pressing the weight into the closed position.

    After 2-3 attempts of testing using just the hub internals (i.e- without the shell on)- mounted in the dropouts, you can turn the hub with the chain and see at what point the counterweights swing out. In my case, I got them to a point of 78RPM (cadence). This equates to a change point of about 27.5km/h.

    Quite motivating and feel=good when it works. Next mopve though is to change the setpoint even higher. I’ll be trying for a change point of around 90-95RPM next attempt!

    Good luck

  113. ok… done a lot of mods in the springs….
    first I unwind the spring almost 90 degree… shift point went to ~20k/h
    to give it even more resistance I bend the spring legs inward … in a 700cc 23 wheel i’m shifting at cadence of ~80 and speed of 25k/h with a combination of 48T chainring and 19T cog ; need to push it a bit more the shiftpoint to a cadence of 90~100 with my bike relation.

    I’ll post photos next time I open up my hub.

  114. Gunnstein, a follow up on my squealing hub. After lubing it twice to no avail I took it to my local bike shop. He thought it was a factory defect and had them send out a new hub. I had laced it with two and a half twists in the spokes for looks and was not wanting to try to undo them. We decided to swap the guts out. When that didn’t work I untwisted and swapped the complete hub and re twisted. The replacement squealed too. At this point, frustrated I took apart a wheel off one of my other bikes and laced in the original hub using the standard pattern without any twists and it worked fine. Only thing I can reason is. that many twists must be distorting the housing. It looks really cool and I’m committed at this point so I’ll just deal with squeal. If I ease into brakes it doesn’t squeal just vibrates a little and I can live with that.

  115. This is Basicaly a Fichtel Sachs Torpedo Automatic hub. It uses the same internals.
    The Germans back in the 60’s made two versions, a red and a blue one, with different shifting points.
    Shifting can be altered by tweaking the spring, as shown on this page:
    He also does a comment on the SRAM Automatix:

    Does SRAM offer differnt spring rates ?
    I can’t find a detailed partslist…

  116. I’m so happy I found this webpage since the gearing ratio on my singlespeed has been driving me nuts.
    I’ve been looking all over for a way to fix the “problem” with my stupendusly low cadence.

    I’m definately going to test this on my bike and hopefully end up with a much more enjoyable ride.
    With a stock gearing of a 46T chainring and an 18 tooth rear cog it’s still a bit on the heavy side.

    However I’ve just changed the rear cog to a 20 tooth instead, but I’ve been looking for 23.
    The same bike is now being sold with a smaller chainring. Maybe I’ll do the same as well.

    Thanks a lot for the pictures, I’m sure they will help

  117. May I ask you an odd question abou
    SRAM – Automatix 2 Speed Hub Freewheel 36H 130 OLD ? would you be able to fit that in a single gear Brompton bike maybe?

  118. Hi, interesting read, I’ve fitted my automatix hub to a 20″ wheel and tried this mod but now only one speed no matter how fast / slow I go;(
    I’m guessing I’ve not put it back right as it’s fairly fiddly (with my fat fingers) did anyone produce a you tube video? I lost count of how many times I hunted on the garage floor for the spring / circlip / my sanity…

  119. I had been using a Carerra Subway hybrid, 26″ wheels with 3 x 8 gears but the rear gear mechanism kept failing. I only ever used about 4 gear combinations and I was constantly whizzing through the rear gears.
    I have replaced the rear hub with the two speed automatic and kept the front 3 chain rings with the supplied 19 tooth rear sprocket. The bike changes ratio at 9.5 mph which is pretty much spot on for my commute and the change is really smooth.
    I am very happy with the unit and I still have the smaller chain rings for hills and headwinds. Another benefit of the system is that I can always pedal off if I have to stop suddenly at a junction. On the rare occasions when I might want to go off road I can just drop out the rear wheel and pop in a 23T rear sprocket.

  120. I’ve been using Sram Automatix with coaster brake, in rebuilt Raleigh Twenty since 2013.
    My commute in Edmonton, AB is 20 minutes one way. Flat as pancake, but often with challenging headwinds. I had gearing set up with 46T chainring and 22T cog.
    I was happy with hub performance and simplicity, except that shifting point…
    Seven days ago I finally decided to take apart the hub and unwind tiny spring.
    Unwinding the spring is tricky, and one should be patient and have tweezers, pliers and flat precision screwdriver.
    After adjustment and lubrication, I changed cog to 19T. My hub works like charm and shifting point suites me better now! Thank you Dave!

  121. Hello everybody,

    I’ve got some difficulties to put the spring back in the correct position. Anyone with a picture ?

    @Simonfromdk : your droplink link is not valid anymore unfortunately :/

  122. Hi, I just got the 36H coaster brake version of the hub (made in 2015 WB49).
    I have 46T cranks and 19T cog on the hub with 700c x 28 tyers. For me it changes gear at 60RMP / 18Km/h. I’m happy just as it is.

  123. Thank you for sharing such an amazing guide!!!

    I was wondering what’s the wire diameter of the spring cable in millimeters ?
    I wish I could make a new spring with a thicker cable to solve the shifting issue, did anyone did that before ? or is there any suggestion of replacing a new stronger spring ?

    Thanks a lot !!!

  124. Hey Dave, quick question, does the coaster brake version comes with the safety bolt-clip which holds the coaster on the frame?

  125. Spring trick seemed to work well, just the ticket! According to a speedometer app on my phone, the shift point on my 26″ wheels went to about 20km/h which is just about right for me.

    However, on my first test-drive after the operation, towards the end of my 15min drive it locked into higher gear!

    After dismantling and inspecting I saw the circlip had gone missing. It seems to have dislodged itself and vanished. Thankfully I found it greased to the inside of the hub casing. I was able to tighten it a bit between a pair of pliers then get it back on again. Hopefully it’s now more firmly in place. I used a flat screwdriver tapped with a small hammer, and tried to pinch the ends of it around the post with some needle-nose pliers.

    Fingers crossed it has done the trick! But it got me thinking that maybe these circlips aren’t designed to be repeatedly removed and reattached; maybe the metal gets warped a bit…

  126. Hi, thx for all the great info.
    Has anybody tried winding the spring in, to lower the change speed? Any reason this would not work? I have the hub on my 5 year old’s 18″ wheel, and have geared it with a bigger sprocket to help him climb hills. I’d like it to swap out of tree-climbing gear into cruising at more like 10 km/h. Going on 7 week tour in a month, so hesitant to risk busting it for no benefit πŸ™‚
    Thanks, Tom

  127. Hi guys,
    I did the spring modification too…
    In my case though, I had to unwind the spring almost 180 deg to raise the shift point to my desired 80 rpm.
    And of course I managed to first loose then destroyed the -very- tiny clip πŸ™
    BTW the clip is DIN 6977 1,9mm, now I have a bag πŸ™‚
    One strange thing is that my hub came without the O-ring and I had a lot of rattles because of that.
    I eliminated those rattles by applying -sticky- chain grease between the hi drive metal disks where normally the O-ring is, I hope it will stay like this.

  128. Any recommendations for a chainring/cog sizes with Gates belt drive for urban riding/commuting, with a few longer bridges to climb?

    Also when you say “137% step” does that mean when mounted with a 20t cog, the two lower ratio is effectively like having a 27.4t cog (20×1.37) ?


  129. hi,

    i changed just like you described, awsome!
    there’s only on problem. My break squakes alot after the adjusment.
    after that i cleaned and greased the brake shoes and the brake arm. no change.

    what to do now? thanks for the help everyone!

  130. I am using this product. It is rubbish, an absolute waste of time. I struggle to think of a situation where this gearing would be of any help to anyone. It rattles about making the bike sound cheap and the ride quality is awful. A single speed or fixed gear would always be better than this.

  131. SRAM provided me with a table of shifting speeds for different wheel and tyre sizes. From that it was possible to calculate the constant – the hub RPM. Out of the box the hub is designed to shift gears at approx 131 RPM.

  132. I use my hub on an old Halfords Carerra hybrid which I have now started to use off road.
    Three speed chain ring on the cranks with the shifter, 26″ wheels and a selection of SA/Nexus rear sprockets. No adjustments made to the bob weights which open up at 9.5 mph.
    19T, 21T (commuting), 23T and 24T. Used the 24T in the Peak District last weekend OK.
    I did have some slipping in top gear prior to that and I had thought that the hub was done for.
    As per previous posts, it was really easy to take out the internals, wash them in white spirit, oil the planets and then grease the ratchets and ball races. Now working fine.

  133. Dave, could you please update us on the details why your hub has failed?
    As an owner of such a hub (w/ Gates CarbonDrive beltdrive) I’m quite interested in its longevity…

  134. Hi Dave, bought the automatix after reading your review. Had the wheel built up and installed it but it just doesn’t seem to spin freely. My Dia Compe freewheel hub spins forever. Is your experience similar?

  135. Well I did the adjust as described because shift point is way too low. Took it for a ride around the block and it shifted 10-15 times perfectly. Maybe not at the exact speed I would like but firmly up and down. HOWEVER… it eventually failed and was stuck in high gear. Upon opening it I saw that the bottom arm of the spring had wedged into the crack that is between that black plate that moves back and forth change gears and “axle” part that the spring rests against. If I could figure out how to post a pic I would. When it wedged into there, it then spun forward so as to push the spring out of position where it rests against the “axle” to give it tension. Tried to straighten it and it broke. Gonna try the click pen spring as mentioned above. But ridiculous that you would design it to shift so badly that the customer has to fiddle it to get to work more practically.

  136. Does anybody else notice a lot of friction in the Automatix when they rotate the cranks backwards? Mine is about double the friction of a normal freewheel. Is that normal?

  137. Tweaked mine yesterday/today.
    I’m running 28`(700C) with 1.75 tyres. Front 39, rear 20.
    First attempt got me stuck in low gear, spinning like crazy with no change, but dont know about speed.
    Today I tried again my luck with the spring, then mounted my phone and installed some speed app. My change point is now about 22km/h, at cadence 85 – suits me!
    Theoretical cadence by that calculator

  138. I’ve done the tweak and it now changes at around 13/14 mph, this is great now. The last ride, I could hear squealing sound. After the I got back home the chain and crank were stiffer to turn. I took apart and the bearings were in place but loose. When I touch move the cage/retainer, some of the bearing can drop out. Is this right? How tight should the nut to the LHS dust/cone cover be? What type of grease is recommended. I cleaned a bit when apart and put Weldtite TF2 lithium grease. Hope you can help. Thanks.

Leave a Reply to wouter Cancel reply

Your email address will not be published. Required fields are marked *