Recumbent efficiency

Go further per calorie – by going laid back

I’ve been putting in the miles on one of my upright bikes recently, ahead of a race where riding recumbent isn’t an option.

I thought I’d spice things up by swapping a session onto the High Baron, using the same PowerTap wheel to see whether I could make anything interesting of the data.

As I suspected, I was faster on my upright than on the High Baron. I wasn’t going flat out on either bike, since I’ve been doing ten or more rides a week – I was only subjectively investing the same effort on each. The outcome mainly reflects training on one bike (many hours) over the other (very little)… the specific effects of training shouldn’t surprise anyone.

What is more interesting is to compare the power I had to use to achieve each performance.

recumbent_vs_road_bike

The route is a little under 25 miles with just over 1300ft of ascent (40km / 400m). Overall, I managed 17.5mph average for 230W on my upright, compared with 16.7mph for 168W on the High Baron.

I think there was more of a headwind on the High Baron ride, but since that only advantages the recumbent, let’s assume that wind conditions were the same:

Each recumbent mile cost 36.2kCal, versus 47.3kCal for each upright mile.

If I’d been racing myself, I’d obviously have won on the upright, but that’s just one way of looking at a performance. What if I was riding an ultra-distance event where I’m mainly limited by how much I can force myself to eat and how little sleep I can survive on?

For every 36 miles ridden on my upright I’d be an extra 11 miles further down the road on my recumbent (for the same effort) and once performance becomes limited by something other than absolute power (i.e. limited by fuel, fatigue, comfort, or any similar factor) that’s really going to tell.

Even on a 200km brevet my average power in the closing hour or so can be as low as 150-175W. I can achieve that on either type of bike, and then you’ve got to think of the next 200, 400, 1000km…

Screen shot 2013-09-20 at 01.00.43

Convergence on hills, as expected

I’ve previously compared the performance of recumbent and road bike in ‘ideal’ conditions (flat without wind) and found a large advantage in favour of the recumbent (250W vs 150W for the same speed).

On the other hand, I’ve also previously bemoaned terrible performance on all-out hill climbs (the MetaBike took 36% longer), where absolute muscle recruitment and platform efficiency is paramount.

It would be expected then for a mixed route / mixed conditions performance to show much less advantage than the ideal case, depending on the proportion of time spent climbing and the proportion at high speed (where aerodynamics offers significant benefit). A flat TT would be very close to the 100W advantage shown in my earlier test, while a hilly ride would be closer to break-even, or perhaps to disadvantage the recumbent altogether, as in the second test.

Pleasingly this is the case for the rides in question: I was 0.8mph faster on upright for 62W extra, which is a much prettier picture than getting the same speed for 150W extra!

If I isolate the hillier section of the route I see 14.1mph for 350W (upright) against 10.6mph for 245W (recumbent). The lack of absolute power is dramatic, but again, only important if each second counts for its own sake (as in a road race or head-to-head hill climb).

Much more interestingly, the efficiency gap has closed right down, to 89.4kCal per mile (upright) against 83.2kCal per mile (recumbent). But…

The recumbent is still more *efficient* on a 10mph climb, albiet *slower*

Since so many people seem prone to equate slow climbing with poor performance it’s hard to emphasise this too much.

If you’re touring you’re hardly going to ride for four hours dead then stop wherever you are at the roadside. You probably have a destination and getting there a few minutes either side is not important compared with getting there in comfort or for less sweat and toil.

If you’re riding an ultra distance event, it’s not likely that you’re so strong that you can maintain high wattages for days at a time; it’s more likely that you want to get the maximum ‘bang for your buck’ when it comes to spending your body’s limited capacity for exertion.

Only if you’re racing over fairly short distances does absolute power outweigh efficiency.

If we buy into the hypothesis that recumbents reduce the muscle mass you can recruit by isolating your legs (which is one possibility) you can see that they really will start to shine as the miles rack up.

recumbent_efficiency1 (1)

Caveats

Other than the obvious (small sample size, indicative only…) the big caveat here is that I’m still measuring power at the wheel and not at the crank. This means it’s possible that one or other of the bikes is systematically under-reading the effort required. What if the much feared phenomena of drivetrain or frame losses mean that the recumbent really requires an extra 50W at the pedals to hit 250W at the cranks?

It’s impossible to answer this question without access to a crank-based meter at the same time as the PowerTap… if anyone has both and would like to run a few tests, get in touch!

For my part, I don’t really see how such a large difference can be accounted for through drivetrain losses: for starters, an idler that sucked out 50W would get as hot as an old-fashioned incandescent bulb, which is patently not the case.

Certainly there are many questions about recumbent performance that remain unanswered, but hopefully this chips away at another aspect of the problem (even if it raises as many questions as it answers!)

Any comments, as ever, gratefully received…

56 Comments

  1. Hi Dave,
    I like to see cyclists ponder these questions and actually collect a little data, as you have done. Why can you produce more power on your DF than your recumbent? I think the answer is the upper body involvement that you get on your DF. There are some DF riders that don’t use their upper body, but I would guess, based on your data, that you do. On a DF, the handlebars can be used as levers to angle the frame and get more power into the cranks. On most recumbents, this is not possible. On a Cruzbike FWD recumbent, it is.

    Jim Parker
    Cruzbike.com

  2. Robert

    Well, it’s possible to measure drivetrain efficiency and losses without both a Power Tap and a spider-based power meter — but it’s easiest that way. You can do it with just a spider- or crank- or pedal-based power meter but you have to take especial care in the test protocol.

    In addition, people often argue that drivetrain losses must be small because otherwise drivetrain components would heat up and they don’t appear to do so — but that ignores both radiative (small) and convective (large) cooling. Metals are pretty good heat conductors so they will tend to conduct heat away from the chain and into the surrounding air.

    Those two points said, I don’t think drivetrain losses are going to be that great.

    What I think is interesting is that when you match perceived effort, you can produce more power on the DF than on the recumbent. Then the question is, is your performance limited more by perceived effort or by actual joules or kilocalories put out?

  3. Jim Clarke

    With Cruzbike it is always the same bullshit, unverified and nonsensical claims. But anyway it is quite clear that on short climb you can’t match the power you develop on a DF with a recumbent, but on a 90mn effort your power should be closer than what you observe. I suggest that you do some specific VO2 training on your bent to increase your power, so that your performance on flat land can be better than on your DF.

  4. Dave

    @Jim Parker – is there any way of getting a Cruzbike up to Edinburgh for me to try out (or maybe a friendly local customer?) I’d be more than happy to give it a fair and open-minded write up, but I’ve never seen a MBB bent in the flesh that hadn’t been home built!

    @Robert – now that I’m spending a lot of time training on the DF I feel acutely that the recumbent platform is isolating a few muscles and they just can’t supply enough power to tax my CV system. Even with a gun to my head I doubt I could work hard enough laid back to max out my heart rate, whereas I can easily get to throwing up or feeling faint on the DF.

    @Jim Clarke, I agree totally that switching my training time over to the bent should increase performance relative to DF. The question in my mind is whether the main effect is going to be to make me faster on bent or just slower on DF though…

    As I’ve now spent a few months really focusing on a couple of (DF) races I may take advantage of being relatively untrained on the bent to do a series on the trainer and see how quickly my performance perks up over the winter. I’ve only got one more event before I’m free to do what I please, and for that one the main thing I need to do is spend time running (duathlons!)

  5. @ Jim Clarke
    I offered to fund a truly scientific study to compare Cruzbike climbing. Please read this:
    http://www.cruzbike.com/proposal-scientific-comparison-bicycle-hill-climbing-performance

    So far, no taker.

    In lieu of that, we’ve raced all over the country:
    My 2012 events, and results, were:

    Florida 400-mile RAAM Challenge: 1st overall, course record
    Mid-Atlantic 100-mile Race: 1st male overall, course record
    Michigan 24-hour National Challenge: 1st male recumbent, 6th overall
    Bike Sebring 12-hour: 1st recumbent (3-way tie), 4th overall
    Heart of the South 200-mile: 1st recumbent, 2nd overall

    But my results pale in comparison to what, my wife, Maria Parker, did in 2012:

    Three new UMCA road world records: 200-mile, 12-hour, and 24-hour
    Mid-Atlantic 100 mile Race: 1st overall (male or female), course record
    Michigan 24-hour National Challenge: 1st female overall, course record
    Bike Sebring 24-hour RAAM-qualifier: 1st overall (male or female), course record
    Heart of the South 200-mile: 1st female, course record

    Then this year, she won RAAM, and it wasn’t just by winning the flat sections. If you take the worst climbing sections of Colorado, the 200 miles through the Rockies from the border with Utah to South Fork, with approx 16,000 ft of climbing, she still was substantially faster than all the other women. And these were some of the best long-distance cyclists in the world. Here were their times in this section. If you take Colorado as a whole, the gap is even larger.
    rider hours bike
    MP 18.9 Cruzbike
    CS 24.8 DF
    SH 25.6 DF
    LD 25.6 DF
    KRW 22.5

    The Cruzbike is DF drivetrain put in a recumbent position. No other recumbent works like that. That’s why it climbs so well, and early adopters around the world are finding that is not “bullshit”.

    @Dave
    A test drive won’t be worth your time or mine. You need to buy one and ride it a thousand miles if you want to do a worthwhile review. There is a big learning curve. Also, I’ve never known anyone to be able to ride both a RWD recumbent and Cruzbike-FWD well.

    Jim

  6. Paul Coombs

    Cruzbike: My bike is better than your bike. I’m so confident that I’m not going to let you test it, but you can buy one and you’ll see.
    Hmmm. Maybe it is, maybe it isn’t, but that doesn’t seem to be the best sales pitch I’ve ever seen. I certainly won’t be finding out any time soon as quite apart from the high price of trying one, I ride a rwd ‘bent so as the man says I won’t be able to ride a cruzbike well in any case

  7. @Paul
    This isn’t a sales pitch. But maybe my bike really is better than your bike. Do you care? What if you could have a recumbent that climbs like a DF?
    You can buy some models of our bikes and return them after 30 days with a $100 restock fee. That’s better than a 10 minute test ride. You’ll still be a newbie after 30 days, but at least on your way to being a confident rider.

  8. Lincoln Brett

    Dave, give up your day job. Just spend your time writing as I really enjoy it. When we ride we form opinions about gear, positions training etc. When you ride, you collect data and make sense (to me anyway). Keep writing more, I have informed work that you won’t be in !

  9. Rodger

    I really appreciate how you are trying to increase knowledge in this area instead of the subjective (think mainstream cycling press) and anecdotal (think internet forums), Your blog is a breath of fresh air. You’re dealing with many variables and limited resources but you are doing something that ought to be straightforward for those in the cycle industry. I’m puzzled by Cruzbike and their mixed messages. What have they got to lose by letting you have a ride? David from Laidback told me in passing that you can ride anything and I believe him. As Cruzbike are having difficulty finding a taker for their research proposal then why not give you a go? They already have got their excuses in early if you don’t concur – you’re too proficient in recumbent RWD, none-MBB FWD recumbents and diamond frames to appreciate the excellence of a Cruzbike… But then again you might like the Cruzbike and support their claims. Meanwhile, I’d like to see you get hold of a crank-based power meter just to measure the drive train losses, if you can’t borrow one then I wonder if any other of your readers might consider joining me in a spot of crowd funding?

  10. Dave

    Hey Rodger,

    Thanks for your kind words… I’d not considered crowdsourcing before, but I’ve popped a topic onto BROL to see if there would be any interest:

    http://www.bentrideronline.com/messageboard/showthread.php?t=101519

  11. Rodger

    Sheesh… BROL was the obvious to capture the highest audience but I think this could do with some positive waves, money where me gob is, I’m in with £100. And I’m a Yorkshire lad!

  12. Hello,

    in my far from humble opinion, if you don’t climb faster on a recumbent than on a DF, there is something wrong. I have written an article on it, see the link.
    In short: forget force. Muscles are easily grown and we all have gears. Also, muscles are only a limit on very short climbs. Weight is important but differences are relatively small, say a few percent. The real difference is in breathing, as this has a major impact on power.
    On a traditional bike, breathing is hampered by the body position. A recumbent can be much more optimized for breathing. But this requires a bicycle that is a little different from a standard fast recumbent, and it requires a different riding technique.
    Most recumbent riders try to mimic the climbing methods of DF-riders. This doesn’t work. Not only because it’s a different bicycle, but also because a DF is a bad climber.

  13. Dave

    Hey Walter,

    Thanks for your comment and the interesting link.

    The main thing that I question is this: it feels like I have loads of spare lung capacity when riding the recumbent, unlike on the upright. My heart rate just doesn’t get that high.

    If my power was being held back by a lack of adequate breathing, shouldn’t I be gasping and trying to supply my heart with enough air, rather than the other way around (trying to give my heart something to do)?

  14. Roy Myers

    Hi Dave
    I am in the middle of preparing a comment about Cruzbike which I have been riding/struggling with for the past six months (I would lend you mine but I live in New Zealand) but thought I needed to add something to your conversation with Walter. When I started riding a recumbent (an ICE trike) 2 years ago I was surprised that I could not get my heart rate up to the level it had been on a DF bike. A sports doctor told me that this was because of difference in venous return between an upright position and the recumbent one. My knowledge on this is very slight unscientific and subjective but someone else may know more. Blood returns to the heart through the veins with the assistance of muscle contraction, the muscular skeletal pump action. Heart rate is obviously dependent on the speed which blood flows back – venous return. I am guessing that in a recumbent position there is less pressure through the system and therefore slower hear rate. This would appear to be good for steady state and endurance activities but not so good for bursts such as sprinting and climbing which explains the differential power and heart rate outputs between the two riding positions. I hope that somebody with more medical knowledge can add to this hypothesis but I think it is a line worth pursuing in the DF /recumbent debate.

  15. Dave

    Thanks for that Roy – very interesting. So it could be that no matter how efficient the bike, because we evolved to run around upright we’re just not cut out (as a population) for high power on our backs…

    I wonder if I could clamp my High Baron on a steep slope somehow (mount my turbo halfway up a wall?) and compare the power output of the same riding position but with gravity under my feet, DF style?

  16. Dave,

    it is natural to have a lower heart rate on a recumbent, because it is easier for your heart to pump the blood through your legs. The Human Power Team has seen this effect several times when selecting riders for the VeloX. The lower heart rate is actually a good thing.
    Of course the rest of your body must be able to use this extra lung capacity. But this can be trained. It might take awhile, however. Breath as deep as possible, even if you feel you don’t need it. Use a low gear. Sooner or later, your body will adapt.

    Greetings,
    Walter

  17. Phil

    +1 to what rodger and lincoln said earlier. I enjoy your blog more than any other on cycling. The mix of reviews, analysis of bike and human performance and the range of subjects you cover is second to none. What is more remarkable is that this is a solo effort.

  18. Rogier

    Dave,

    Interesting to see that during climbing the recumbent seems to require less kCal per mile then the upright bike. I wonder how much this is due to the lower speed during climbing with the recumbent. It would be interesting to see what happens when you do the climbing on the upright bike with the same speed as you did on the recumbent. This way you could tell if the difference is due to the bike or due to the speed.

    Rogier

  19. Dave

    Hi Rogier,

    Good suggestion. It won’t be too hard to measure so I’ll try to find some time for a follow-up article where I compare the two bikes at the same speed.

    Thanks,

    Dave

  20. Petter Wingren

    Very interesting read. Your results explain why I seem to do better in my brevets the longer they are compared to DF riders. (Compared 200k results to 400k results, riding on a M5 CHR.)

  21. Magnus

    Hi Dave!
    Nice article, but also a bit surprising to me. I read your first review of the HighBaron and bought myself one about a year ago expecting to become a faster bikerider. I started ridning it this year and I think I have a sufficient amount of data by now to compare it to riding upright. For upright ridning I have a Scott SUB 30 converted to cx. On my regular routes – the shortest 17 km, the longest about 100 km I’m consitently faster on the HighBaron (32-34 km/h compared to 28-31 km/h). Typical route data 55 km and 400 m ascent where the ascents rarely are more than 5-7%.
    Learning to ride the HighBaron with good control took me some time, and I still have some skills I’d like to develop more. After about 2 months of riding the increase in speed started to level out between rides and I consider it reasonable to draw some at least preliminary conclusions:
    On my routes I ride the HighBaron about 10% faster (average speed) than the cx. On ascents up to about 5% the HighBaron is faster, but as it gets steeper the cx starts to match and is better the steeper it gets. When comparing speed on flat roads or downhill the HighBaron actaully is about 20% faster than the cx. However, the reason the average speed is only 10% faster than the cx is only to some extent explained by the ascending performance. A more important factor is the handling i sharp corners, poor road conditions and acceleration from stop.

  22. Dave

    Hi Magnus,

    Thanks for the update on how you’re getting on!

    I think it’s important not to read too much into the relative performance, but rather the energy use per mile.

    As I’ve been spending a lot of time training on my ordinary bike for a couple of races and much less time riding the Baron, it’s not too suprising that my form on the racer is good enough to outweigh the efficiency savings.

  23. Great blog Dave ~

    Your last entry nailed it. You have the logic to know what needs to be done for your recumbent performance to improve – more time in the saddle. I know of no one that can just hop on a performance recumbent “bent” and ride as fast or faster compared to their racing upright they have spent years and years on.

    Thanks for addressing the bent vs upright topic that always draws criticism from the un-informed. It takes a minimum of a thousand consistent miles before the bent legs kick in. Then you will then start to feel invincible and understand how the performance records are set by bents. It’s not “all” about power when riding recumbent. Big kudos go to aerodynamics. Mix the two – WOW!

    Think of recumbents as the multitool of cycling. Which recumbent platform will be the best suited for the event. Where as upright bikes are squeezed into such a tight box of regulations that it’s hard to make any significant new frame design improvements to stay with in international race specifications.

    Recumbents basically only have two categories to live by – (faired vs unfaired)

    Until a upright rider is ready to give up the flock he/she rides with, they will always be an upright rider. I will say this for any potential National Champion – It is much easier to become a world champion through the International Human Power organization than the UCI or any other upright bicycle category. WHY? There will only be a couple dozen riders to compete against vs. hundreds in the upright clubs.

    Bent riders can climb with the best if they are of equal fitness. I know of a couple of racing recumbent brands that are show room stock at 24 lbs. A racer/rider can make a sub 20 lb. with little effort.

    Why do I ride a heavier 28lb faired bent? I like to ride 30% more efficient than an upright rider. For me, it is all about how many miles I can ride at 21 mph for the least amount of calories – just like the eco cars of today. Yes – I do a lot of coasting riding along with upright riders. A well ridden faired bent will carry an extreme amount of momentum in 175 ft rollers. Long 6% climbs are slower than a upright roadie because of the weight penalty. If grinding out fast climbs is your thing then select the lighter unfaired high racer category as your tool of choice.

    Keep up the good blogging.

    Lonnie Morse
    Recumbent Aerodynamics blog

  24. Dave

    Hi Lonnie,

    Thanks for your comments. I hope after five or so years (including finishing Paris-Brest-Paris) that I have reasonable adaptation to riding laid back. However, there’s no doubt in my mind that you lose it so quickly – a season training on upright and bang… back to the beginning :)

  25. Dave

    I actually have no idea how many recumbent miles I must have ridden although I guess I could dive into my GPS traces to try and work it out. I want to guess around 20,000?

  26. Joe

    Very good study. I like where you are going.

    The muscle activation patterns of the legs should be very similar between the two bikes, see here for more info: http://sportbiomech.blogspot.com/2014/03/why-upright-and-recumbant-cycling.html

    Now, similar coordination and muscle activation levels does not be similar efficiency. Not having done the proper experiment (which you are getting toward but have not arrived), I would hypothesize that recumbent would be more efficient.

    Why? Because for similar muscular & caloric demand, the recumbent fixes your torso in place, whereas in upright cycling, some of the force when you push down on the pedal can accelerate your torso upwards, which is just wasted energy. Note that you don’t actually lift your torso off the seat b/c the force is not sufficient. Also, you expend some arm energy preventing the torso from moving.

    In addition, the recumbent position offers a more neutral pelvis and hip angles which could have some benefits (I touch on these at the end of the blog post I linked to).

    Joe
    However, if you are more adapted to upright cycling, then comparison of time up a hill are kind of flawed unless you are equally adapted between both bikes. Are you in the same gear / RPMs on each bike during the climb?

  27. Dave

    Hi Joe,

    There are lots of indicators but few good observations where confounding factors are controlled .

    I have variable GPS data going back for over 5 years on DF & recumbent now – at times I was very strong laid back, more recently I’m strong upright. Personally I find it strongly suggestive that over this long a time period I’ve never managed to get my heart rate nearly as high on a recumbent as I can get it on an upright (and again, never as high on an upright as on foot).

    This suggests something systematic rather than just conditioning, but I’m not too keen to spend time experimenting on myself in that way (lots of effort and inconvenience, still a data set of 1).

    Thanks,

  28. Dave

    Also, just to quickly pick up on the article you’ve linked – muscle activation is patently not the same between the two platforms, as I’d expect you to estabish by riding for a few minutes and listening to your own body. I find the medial head of quads and hip flexors burn furiously when I transition to a laid back position and push it, and even after some adaptation time there’s still a markedly dissimilar feeling in the legs.

    I don’t doubt that your personal experience is that they are the same, but I do find it very odd.

  29. Joe

    Hi Dave,

    Bunch of interesting notes. (btw in my blog I discuss the basic mechanics, but link to a experimental study of multiple subjects that concludes no difference. Not my personal test).

    Are your hip – crank axis, pedal – foot, and crank Q factors exactly the same on both bikes? Any differences in those values alters the mechanics.

    What is the difference in heartate that you could achieve between the two styles? The difference between running and cycling is part that cycling uses less muscle mass and there is “harder” on individual muscles, as well as higher arterial pressure resistance that the heart has to work against.

  30. Dave

    Hi Joe,

    I see now that the study basically equalises the riding positions, has one rotated, then concludes that muscle use is the same, which I suppose isn’t surprising.

    In reality, you can’t get a recumbent which matches your hip angle to that of an upright (which hip angle anyway? upright shopper? time trial bike?) – to be honest, I can’t imagine how you could make a proper recumbent (seat angle ~25 degrees) anything like an upright, mechanically, since the way you apply pressure is completely different – against the lower back with the hips more “free”, but also open.

    Pedal to foot matching sounds unlikely (for the same relationship between foot and axle I’d expect a cleat movement is required, since the way you push is quite different).

    I guess Q-factor could be the same, since the BB / cranks are a standard part.

    I can’t remember off-hand my HR differences but I want to say something along the lines of 10-15bpm?

  31. Paul Kotschy

    Hi Dave,

    I hope I’m not too late to submit a posting here.

    I can attest to your findings. I agree that, relative to my DF position, my recumbent position imposes physiological impediments to my body’s ability to deliver power to the wheel.

    I have two hypotheses for this. The first concerns power delivery itself. The second concerns efficiency of the power delivery.

    1. By constraining any hip, back and shoulder movement, only my leg muscles are left to deliver power. In contrast, the DF position frees my hip, back and shoulders to contribute. Even though these contributions may be small relative to those of my legs, they add up. Indeed, this is exemplified when standing up out of the saddle.

    2. On my recumbent bike, the reaction to the pressure applied on the pedals is a pressure against the seat. I’ve noticed that, ordinarily, this reaction pressure causes my back (under the skin of my back) to move relative to the seat. This movement is ostensibly non-conservative (i.e., it is energy lossy), thereby constituting an energy drain. I believe this energy drain to be non-negligible.

    I’ve tested this qualitatively by rhythmically pulling on my recumbent bike’s handlebars while pedalling, such that my back no longer moves relative to the seat. This eliminates that energy drain. I notice that I am able to climb and cruise better when doing this.

    On a DF bike, the reaction to the downwardly applied pressure on the pedals is a pressure directed upwards, which pressure will tend to raise my bum out of the saddle, thereby repelling gravity. But this movement is conservative. That is, any energy lost repelling gravity is fully recovered as my body lowers. Furthermore, these vertical movements are very small. The DF bike therefore does not suffer the same energy drain.

    As an aside, based on my two hypotheses, I believe there to be some merit in Jim Parker’s assertions regarding his Cruzbike FWD recumbent.

    Kind regards,
    Paul Kotschy

  32. Dave

    Hi Paul,

    Thanks for a great comment, it’s good to hear your thoughts.

    Back in summer I wasn’t in very specific condition for laid back riding, and finding things a bit of a struggle so looking for any small gains that I could get.

    I discovered that I significantly improved my power output – or at least, reduced my perceived effort at a given power – by packing the seat back (under the seat pad) with a horizontal ridge of foam, roughly around the level of my iliac crest. My conjecture is that this frees up the muscles downstream of this point to contribute more effectively to the pedalling motion. It’s just anecdotal of course – there are too many variables to really see what’s going on even with the power meter, but I really felt a difference when putting out a higher effort (a 10 minute climb, say).

    I also found that gripping and pulling on the bars really hard helped me deliver more power to the pedals, but unfortunately my arms weren’t really strong enough to stabilise my body for long in that way. I toyed with the idea of shoulder braces at the top of the seat but never progressed the idea.

    Thanks for your input!

  33. Paul M

    Intereting stuff. going back to Walter’s comment “he real difference is in breathing, as this has a major impact on power.” Whilst no a sport scientist, I’ve read enough ( http://www.amazon.co.uk/Breathe-Strong-Perform-Better-McConnell/dp/0736091696 ) to know that this is only true at anaerobic levels, except indirectly in that efficency breathing using less power itself . At aerobic levels the ‘weakest link’ is the blood deiivering oxygen. Which is why EPO has an important effect…..

  34. Johnny McWheels

    I can compare bents with DFs from when I was more ‘match-fit’, commuting in and out of London for 2 years. I had then a thin steel DF tourer, too big for me, but because I could only use the drops, I was out of the saddle very rarely. In parallel, my wife was riding a TerraTrike Cruiser, she’s basically the same height as me but with longer legs. Neither bike/trike is lightweight, but by comparison, the trike is about 2½ times heavier and has absolutely nothing on any inclines when the DF is still rolling.

    At one of the BHPC events we used to go to, she was ill, so I took the reigns (http://www.bhpc.org.uk/Data/Sites/1/media/events/events12/hayes2-12.html). I wasn’t practiced as a bent racer, but I was always able to take chunks out of the roadies on any incline on the DF commute into work, and always without coming out of the saddle or pulling on the bike. So I think I was probably used to not recruiting my top half much.

    What I can say about the 45 minute race was that I should have pushed the seat forward yet another couple of inches, ones calves were feeling it. However, my average speed was higher than I expected, and I was still making most gains up the inclines of the 0.9 mile track (through the bomb crater) than anywhere else. Never had a power meter, so can’t comment, and my average commute into London was 45 minutes on a good day for 12 and a bit miles, but with 28 traffic lights and zebra crossings to negotiate. Trike would have been slower, but I put that down to weight and not being able to filter past the cars.

  35. Stephen

    Hi Dave

    Interesting article! I like your idea about the idler getting hot, but I’m not sure if it is quite right. I would think that the majority of losses from the idler come from within the chain itself, as it is forced to bend under load, causing the parts of the chain to rub against each other. I do not think there will be much friction in the bearings of the idler, and I don’t think there will be much friction between the chain and the idler as drive is not being transferred.

    I did a back-of-an-envelope calculation of the heat transfer coefficient from the chain due to forced convection, assuming you are travelling at 15 mph, and I got 5.6 W/degC. In other words, if 50W were being lost in the chain, it would be around 10 degrees warmer than the ambient air temperature. However, I only considered heat transfer from the outer plates of the chain, not the rollers and inner surfaces, so in reality the heat transfer coefficient could be double what I calculated. I’m not sure whether I would notice a 5 degree difference, and I generally try to avoid touching the chain anyway!

    Having said that, I don’t think the drivetrain losses can be that much higher than for an upright bike. If we assume that losses from the drive side of the chain are purely due to bending the chain under load, using results from (http://fahrradzukunft.de/17/wirkungsgradmessungen-an-nabenschaltungen-2/) I estimate losses of 0.12% per degree of chain bend. However, the chain is under tension on both sides of the idler so the value has to be doubled. If the power idler bends each chain link by say 10 degrees, that would give a loss of 2.4%.
    On the return side, using the same website, a “somewhat worn-out” chain tensioner adds a constant 2-3W. I can’t think that the two return idlers would be so much more than this.

    Thus total additional losses due to being a recumbent would be around 8W at power output of 200W. However, I have made lots of assumptions, so measuring it would definitely be better!!

  36. Nik Heathman

    Jumping in very late to the thread, but all interesting stuff. I have occasionally owned recumbents over the last 20 years – Kingcycle, Baron low racer, Catrike and currently a Quest Velomobile. I live in Devon (very hilly) and have always found climbing the main issue with ‘bents, but I haven’t really spent enough time to adapt anywhere near fully to give a final verdict. I can say however a 33kg velo isn’t climbing anything vaguely steep over 300 yards quickly.
    I do want to get a Cruzbike Vendetta in the next year or so as it does sound like it might suit the local terrain better – just need the pound to rise against the dollar a bit. I’m currently riding DF’s exclusively to the tune of 20000kms in the last year so may be able to get some good averaged data eventually.

  37. David

    Hi Dave,

    also jumping in late on an old thread. I am very interested in this topic, having just got into recumbents (600 miles in, bought a Fuego from David at Laid Back Bikes based on the fantastic detailed reviews on your site, and David G’s great advice and enthusiasm on a try out! Too many Davids around here though….)

    I am not particularly interested in being the fastest thing on two wheels or I wouldn’t have bought a Fuego (and I’m also 41), but I am very interested in mechanical efficiency.

    I have to admit I think I am in a very niche group – first one being a recumbent rider, but more specifically, I have been training in Alexander Technique for over 15 years now and it has profoundly changed the way I look at the use of the body and what it is able to do.

    Having just got the ‘recumbent bug’ I am very interested in what I can do on a bent, and have discussed this with my AT teacher at some length. His opinion is, for a bent rider who is able to fully utilise the body in the mechanically optimum way promoted by AT (which may not accord with what science says is best, but based on my own AT experience I have to concur that science doesn’t always know best), you should be able to get more power to the cranks than is possible on a DF. He has never ridden a bent so it’s a hypothesis only, although my experience over the years has been that he is rarely wrong on any matter within his field of expertise. He also backs up what Walter says about breathing, although my understanding is that improved breathing is a side effect of AT application and not a direct goal in itself, it happens naturally.

    I am coming to the conclusion that ‘bents can’t climb’ is a myth, although I’m still some way off proving that directly myself. I am still in early days adoption, however I think I am climbing ‘about the same’ as I used to on my hybrid. I have had occasional moments where my AT training has worked really well and my legs have felt like pistons directly connected off my back. During these circumstances I have felt it much easier to climb and can see that there’s definitely something in there to investigate further.

    It’s an interesting thing to investigate and I’m enjoying it immensely. I was thinking that, as someone who is clearly extremely fit and strong going by your ToTB result this year, you might be interested in the application of AT to cycling yourself.

    Cheers
    Davud

  38. Dave

    Thanks David, I’ll look into the Alexander Technique. Let me know what you think as you increase your adaption to the Fuego too!

  39. Maksym

    Inspired by Dave’s posts, bought a Challenge Chamsin 26″. Still waiting for the rack though.
    Before that I was riding a Specialized Hardrock 29″. Needless to say, recumbent is much, much more comfortable to ride. Here in London, I could not do without at least some kind of suspension, so I’m happy that the Chamsin has the rear one. It might be not the lightest bike in town, but not the heaviest either.
    After the purchase I read somewhere that there are also so-called FWD recumbents, such as Raptobike, that climb much better. I don’t really understand why that should be the case ( the BB position is quite similar to what I have on Chamsin ), but on Chamsin, I should really work hard on a 16% ascent to make at most 8 kmph… And the second question – if FWD bikes are all the way better, why there are only a few manufacturers making them???

    Would really appreciate some input on this.
    Thanks, Maksym!

  40. Dave

    In short, I don’t believe they are faster. There’s no obvious source of inefficiency on a RWD that you are removing by switching to FWD.

    I could believe in the case of moving-bottom-bracket bikes that there is a difference in supply power (your body can produce more power due to the involvement of your arms and core). Perhaps – it’s at least plausible.

  41. If you are enjoying riding and racing your RWD recumbents, by all means, stick with them.

    However, don’t discount FWD until you have adapted to it and given it a fair trial. Keep in mind that not all FWD designs are the same. Cruzbike uses a patented design on its race bike, the V20. No other FWD bike ever had this type of drivetrain until we built it. It’s stiffer and more efficient than the home-built FWD versions built and raced (successfully) over the past 40 years. No other company uses a FWD design like ours because of the patent. Our bikes have been sold in 40 countries and all 50 US states.
    Don’t take my word for it, but go to our forum and ask people with no financial ties to the company if they climb better. We have hundreds of customers who have a lot more experience riding RWD recumbents than I do, who will verify from their own experience that they climb faster than their previously-owned RWD bents.
    As further evidence, consider performance in races with lots of climbing such as the Assault on Mt. Mitchell (Mt Mitchell is the tallest mountain in the eastern half of the US and Canada). The fastest times for recumbent men and women were set on a Cruzbike.
    http://www.bentrideronline.com/messageboard/showthread.php?t=118184&highlight=aomm
    In California, the most serious title for climbing is the California Triple Crown Series, which goes to the cyclist with the shortest cumulative time in three mountain double centuries. This year, those three extremely tough 200 mile races were: the Devil Mountain Double Century (with 20,000 feet of climbing), the Central Coast Highland Double (with 14,436 feet of climbing) and the White Mountain Highland Double (with 13,529 feet of climbing). These are events that recumbent racers rarely dare to enter, and if they even finish hours behind the standard bike racers, they receive accolades on the recumbent forums. This year Jason Perez, racing his Cruzbike V20, had the fastest overall time and was the Triple Crown winner. Never has a recumbent racer beat all the standard bike racers in an event with so much climbing (total of nearly 48,000 ft in 600 miles).
    I think most people intrinsically understand that a RWD bent drive chain that is 300% longer than a standard bike (or Cruzbike), with added pulleys or chain guides, is going to be less efficient. I also think most people understand that containing the drive forces within a compact rigid structure is more efficient than distributing them across an entire frame, where flex can occur. Both standard bikes and Cruzbikes confine the drivetrain within a compact tetrahedron.
    Less easy to understand is the advantage of a direct connection between the upper and lower body through the handlebar that exists on the V20 and standard bikes, but not on RWD bents. It’s something most people need to experience to understand, but as a thought experiment, imagine a constant force pushing down on a standard left bike pedal in the 9:00 position (crank straight forward). Now imagine a tiny flat digital scale between the rider’s foot and the pedal. If the rider pulls up on the left handlebar, leaning the frame slightly to the right, the force on the pedal will momentarily go up (the digital readout will increase) with no increase in force from the leg. On a Cruzbike, the same (or very similar) interaction takes place though the system is rotated about 90 degrees. Pulling on the left handlebar slightly deviates the BB/crank toward the left, shortening the distance to the left hip, just as leaning the standard bike does, resulting in more force to the pedal without an increase in force from the leg. This is part of the secret of climbing fast on a Cruzbike. Beginners cannot take advantage of this because their efforts are uncoordinated, but with enough time on the bike, this advantage will develop naturally. Once adapted, Cruzbike riders ride just as straight as any other cyclists, and have the option of engaging the upper body, or not, just like standard bike riders.
    Course records have been set on Cruzbikes at many of the biggest flat races in the US (those races that allow recumbents) such as Bike Sebring, Calvin’s Challenge, and Bessie’s Creek Time Trial. My wife set the 24-hour record at Bessie’s Creek for both men and women on standard or recumbent bikes this year. I set the 6-hour course record. Less chain is not only less moving mass, but it is more aerodynamic.

    I love recumbents and ultracycling. Think about getting a V20 if you are serious about speed and climbing. But either way, I hope you have great success and fun with your cycling.

    Jim Parker, MD
    Director, Cruzbike
    Cruzbike.com

  42. Maksym

    Thanks for sharing your thoughts, Jim. Sounds really intriguing. I even checked the website in your signature. I also browsed few other similar threads, and in almost every of those I spotted your comments. Cool advertisement campaign, I must admit :) Here are the problems I see so far ( not being expert with frame designs and such things).
    No dealers in Europe. For some reason, European shops do not stock your bikes, and this is already a warning sign for me. Once I get problems, how would I realize my warranty right? Next thing – for the same reason I cannot give the bike a fair try, just because there is no place I could rent one. The losses in drivetrain are there, but they are not that significant. Also, longer chain lasts three times longer, doesn’t it ? :) You mentioned that compact design is better. I agree with that, but then neither on the DFs nor the RWD recumbents the drivetrain is attached to a steering wheel, which of course reduces reliability, because you not only push it with your feet, but also pull with your hands! And all this stuff is attached to a thin fork ( together with a wheel!). Very significant factor – the price, which is twice higher than the one of a normal recumbent. For this price I can buy a custom-made DF on a titanium frame, which will obviously climb faster))) And, after all, cycling is not just about climbing, it is also about descending, and here any recumbent will shine. Even on a not-so-steep descent I already can reach 55 kmph, and this is with only 150 km recumbent experience in total! The following may seem kind of childish, but I just don’t like the design of the Cruzbike. Nothing personal, but aestetically my Chamsin looks much more attractive to me. The best would be Troytec, but since it is dead…
    Regarding your wife’s achievements – my respect, that’s really unbelievable! But, to be honest, I thing she could do the same on any recumbent, since there are no bad bikes – there are only bad cyclists :)

  43. David

    It’s worth pointing out that Dave won the Tour o’ The Borders on a RWD recumbent this year (Optima High Baron). Some decent hills on that route. Not exactly tens of thousands of feet but still, it’s not a flat race. Would Dave be faster on a FWD? Who knows, but he’s already doing pretty good on his High Baron!

  44. Maksym

    Yep, that’s exactly what I mean when saying about the good cyclists. I watched the video, the terrain definitely does not look flat :).

  45. Maksym raised several points (posted October 17, 2016) that may be beyond the scope of this thread on “Recumbent efficiency” but I will respond to them:

    >Here are the problems I see so far (not being expert with frame designs and such things).
    >No dealers in Europe. For some reason, European shops do not stock your bikes,
    >and this is already a warning sign for me. Once I get problems, how would I realize my
    > warranty right?

    Our dealers are listed at http://cruzbike.com/dealers. As much as we have tried to cultivate dealers, very few are willing to take on a new 2-wheel recumbent brand. Many 2-wheel recumbent makers have folded. The internet has made direct sales a more viable option for bike brands both large and small. However, we do have a dealer in France:
    http://cycles-bentoline.com/
    Another dynamic of the internet on small businesses is that your reputation is everything. For any bike we sell directly, we provide support, regardless of the country. We’ve sold many bikes in the UK directly to customers. Check out our reputation for customer support on the Cruzbike forum or Bentrider online’s forum.

    >Next thing – for the same reason I cannot give the bike a fair try, just because there is no
    > place I could rent one.

    We aim to do better than that, and will actually try to match you up with a Cruzbike owner within an easy drive from your location. http://cruzbike.com/ride

    > You mentioned that compact design is better. I agree with that, but then neither on the
    >DFs nor the RWD recumbents the drivetrain is attached to a steering wheel, which of
    >course reduces reliability, because you not only push it with your feet, but also pull with
    > your hands! And all this stuff is attached to a thin fork ( together with a wheel!).

    The fork is made to our specifications and we haven’t had one break, ever. The fact that the front end is triangulated (fork, chainstay, and boom) makes it incredibly strong.

    >Very significant factor – the price, which is twice higher than the one of a normal
    >recumbent.

    You would need to define the price of a “normal” recumbent. Our QX100 retails for US$1749 making it one of the most affordable recumbents on the market. The V20 is a world-class racing bike weighing about 22 lbs. The frameset sells for US$2650, which is competitive with other lightweight racing recumbents. It can be purchased in the US fully-built and ready to ride for $4500, also competitive with other bikes in this class. Many European customers prefer to buy the frameset and build the bike with wheels and components from their DF bike.

    >The following may seem kind of childish, but I just don’t like the design of the Cruzbike.
    >Nothing personal, but aestetically my Chamsin looks much more attractive to me. The
    >best would be Troytec, but since it is dead…

    Beauty is in the eye of the beholder. I love the way our bikes look, but you might expect that. There are some very beautiful RWD recumbent frames, I would agree. But when the long chain goes on, that just ruins the aesthetic for me. There is nothing attractive about saggy chains bumping into the front tire, frame, or my leg on a RWD bent.

    >… there are no bad bikes – there are only bad cyclists.

    I agree there are no bad bikes. But there are slow bikes, and bikes that don’t climb well. The rider is a very important part of performance, but so is the bike. We aim to make bikes for a wide range of riders. The video at this link tells some of their stories and you can see many of our bikes in action: http://cruzbike.com/your-open-road .

    Jim Parker
    Cruzbike

  46. Maksym

    Hey Jim, I promised Dave in a separate email that this will be my last post on this topic, don’t really want to flame. I just would like to say that, comparing to other manufacturers, your marketing is too agressive, and sometimes, to defend your position, you use some methods that I would, due to my poor English vocabulary, describe as “not very clean”. None of the problems you mentioned about the chain I experience on my recumbent, but if people read your post, they would think that this holds true for any recumbent except yours. In your earlier post, you said that if I am serious about cycling and climbing, I should get your bike. Not only this sounds offensive ( if I bought a different bike, than I am not serious and don’t want to go fast, right? ), but it also assumes that all other bikes are inferior ( slower, heavier, put your word here), and only Cruzbike shines everywhere. If I really wanted to climb, I would opt for titanium DF, which would be much lighter, more durable and with a lifetime warranty on a frame ( here in London there are options for that ), and not just two years as for Cruzbike. And that’s for $4.5K without EU tax and delivery! Even my $500 Specialized Hardrock offered five years frame warranty! My aim of getting a recumbent was to get more miles per watt, and, according to Dave’s tests, this is perfectly achievable. Again, I don’t want to involve my upper part of the body, because indeed I will just get another DF in recumbent position, but without ability to use my body weight ( gravity) to assist on climbs.

  47. Hi Maksym,
    You made a lot of good points. The buying decision for a bike is more than mechanical climbing efficiency and speed. Purchase and maintenance costs, warranties, aesthetics, etc. all play a role. You should feel good about your bike. I think you made a wise decision to switch to a recumbent. As an MD, I have done a lot of reading on the health risks of standard bikes. When you undertand the anatomy of the pelvis, riding long distance on a standard saddle is really not a good idea for many people. But that is a topic for another thread.

    It’s widely accepted that the extra moving mass of a long chain costs energy, and that there is energy loss every time chain-links flex. I did not intend to offend you or mislead any readers in my last post commenting on the aesthetics of a long chain on RWD bents. Looking back at the context of the thread, I hope it is clear that was my opinion on how they look and feel on otherwise beautiful frames.

    One more point, I don’t view posting on recumbent forums or threads as “marketing” because I view myself as a cyclist first, and one who knows more about FWD dynamics than just about anyone on the planet. I rode my bike 83 miles today. I like to share my experience with those who are open-minded and want to learn about something most bicycle “experts” really know little about. Dave posted this about FWD bikes a few days ago that prompted me to post again on this thread. Dave wrote: “In short, I don’t believe they are faster. There’s no obvious source of inefficiency on a RWD that you are removing by switching to FWD.”

    I disagreed, respectfully, with that, and gave a fairly technical explanation. I appreciate the opportunity to express my thoughts on this issue. Ride on.

    Jim Parker
    Cruzbike

  48. Maksym

    Hi Jim, sorry if I was too straight or misunderstood your point. I highly respect the efforts you guys do at Cruzbike to increase the “population” of recumbents and their technical specs. Perhaps in the future Cruzbike will change the biking world just like Tesla is doing now for cars!

  49. Dave

    Perhaps my wording was a little loose. I don’t believe that if we added an MBB design we’d find it requires fewer calories per mile, which is the focus of the article.

    I’m comfortable with the idea that it can allow a higher power output, after all this is what I see between my DF road bike and the High Baron. When I rode in the Alps last year I was climbing with average wattages for an hour on the DF that I can’t sustain for more than a 20 minute interval training session on the High Baron. Despite turbo training 2×20 minute sessions on the High Baron all year…

  50. David

    Dave,

    Based on your last comment, you can sustain what sounds like considerably higher power on the DF over an hours’ climbing in the Alps, and yet you can still beat an entire field of DF riders on the High Baron over 3 and a half hours hilly terrain.

    Is the conclusion here that the aero advantage of the recumbent outweighs the reduction in power? On hill climbing it’s all about power / weight and other factors become less important, which would suggest that on a pure uphill race, you would fare less well. Is this correct? If that is so, there would be a crossover point where a DF becomes more desirable (in terms of average speed) than a recumbent. I’m curious about what kind of terrain you might think that would become the case, if at all. Either that or perhaps I am missing some piece of the puzzle here.

    Cheers
    David

  51. Maksym

    I am not a professional DF rider, but when I attack the hill, I can stand on pedals with my whole weight, so there is a gravity assistance. At the same time, I lean the bike to the opposite side to prevent falling. If I don’t stand, then my efficiency on DF is similar to the one on recumbent. But I’ve just the beginner in recumbents, so I hope the situation will improve.

  52. Dave

    Yes. Even with equal weights, in a hill climb race I would stand no chance at all on the High Baron against myself on a DF. My power is far higher (but of course, it’s also far more exhausting). It’s not clear why that is, but it isn’t due to the frame or chain because I’m measuring power at the cranks, before these losses take place.

    Tour o’ the Borders is not all that hilly in absolute terms – 1450m in 120km – and the advantage of the High Baron outweighed the losses on the climbs on that ride, but only just. I built up a seven minute lead on the DF pack before the first hill. I was fastest rider by just 5 seconds once the hills were over…

    The big question to keep in mind is, how much power can you produce before you hit the wall (on any bike)? Just because I can put out an extra 100W climbing on the DF doesn’t mean I can ride at 300W all day. If I can only sustain 200W for the length of ride, any bike that I can put out 200W on, will be competitive on other factors. Does that make sense?

  53. David

    Makes perfect sense Dave.

    Still curious about long climbs – if you make it long enough that you would exhaust yourself at the higher power output you can exert on the DF (i.e. the climb forces you down to a power level that you can sustain on the bent), then the bent should win since it is more efficient per watt. Is that correct?

    Interesting discussion!

  54. David

    As an aside to all this, I plan to do some testing of my own on power generation from the point of view of Alexander Technique on the turbo trainer. I believe there are some things there that can be beneficial. I don’t have a power meter unfortunately (I’ve already spent well more than I should have this year on new bike stuff!) but if I get any insights I’ll be sure to pass them on.

    All the best
    David

  55. Dave

    If it was a long enough climb to make my sustainable power the same on both bikes, then it would come down to weight – assuming it’s steep enough to factor out the aerodynamic differences.

    You lose a few KG going to a recumbent platform so it would be a few % less efficient to climb on. The combined figure in the original article reflects the cumulative savings of lots of time at aero speeds.

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