Dynamo Hub Weight

Hard currency illustrates illumination information

I’m building a new dynamo wheel and thought it would be interesting to compare the weight with the Li-Po battery LEDs I used previously.

Based on the Shutter Precision PV8 hub (not the light weight SV8 version), I expected the dynamo setup to be quite a bit heavier, but in fact the weight difference was just 25g.

On the lights themselves, the IQ Cyo is about 30g heavier than the Ay-Ups, but the RSP Astrum is 30g heavier than the Toplight Line Plus rear light, making that a wash.

dynamo_weight2 (1)

Let’s throw in 10g for the tail-light wire and you get 35g – roughly the weight of five 2p coins. If you wouldn’t throw away that much change after a commercial control or cafe stop, you probably shouldn’t try to justify a battery setup on weight grounds alone 😛

(Yes, it’s true that there are many other reasons why you might prefer batteries – I used them exclusively myself, until recently).

Of course, the battery pictured is only just enough battery for one summer night. In reality I took two on all long brevets, which tips the scales in the dynamo’s favour by a cool 100g…

dynamo_weight1 (1)

This doesn’t touch on the two real issues that split dynamo / battery use: drag (which is now the subject of a dedicated article on hub dynamo friction) and efficacy, but I wanted to take a few minutes to illustrate that what many percieve to be a significant downside of dynamo use just isn’t…

Even Wiggle are getting in on the hub dynamo action: get yours here.

4 Comments

  1. Thus far, my SV8 has done very well over 3300km in my Nazca Pioneer. It clearly ‘spins’ longer than other dynamo hubs. Besides being light, it also is tiny.
    For a bike that I use for most rides, at any time of the day, I can’t think up anything better than a good hub dynamo system. It just works, always. A little over 10.000km now. Before the SV8,I had a bulky Shimano hub. That also worked.

    Peter

  2. Dave

    Good to hear Peter – the main question in my mind (vs SON Delux) is the reliability of the SP hubs.

    This one produces the same power as the full SON hub (important for charging) but weighs just the same as the SON delux. It’s built into a lovely wheel now, I’m just needing to decide on a bike to put it on (pretty sure it will be a High Baron admittedly).

    In fact I have some pics to upload now…

  3. Nick F

    Great wheelset! I’m also thinking of building a wheelset on HplusSon Archetype rims for the benefits of wider tyres, and I’d plan to use them for the LEL that I’ve been foolish enough to enter. This will be my first Audax, so I’d be using night lights for the first time, and I’d be grateful for any advice/opinions.

    I currently have two Lezyne Superdrive LED lights which can take either rechargeable or standard batteries (which are small and pretty light). Since recharging could be a problem during the LEL, I was planning on taking several sets of standard batteries. But reading your article has turned me on to the possibility of a dedicated wheelset using a dynamo hub.

    What are the pros/cons of dynamos over batteries in your opinion? Would a dynamo hub add to pedaling resistance – when lights are on, and when off? I’d be anxious that if there was an electrical failure in the dynamo I’d be in the s***, but back-up batteries would make it pointless to have a dynamo!

    Any comments gratefully received. (BTW some more great articles in your blog Dave. I appreciate the thought that goes into them and enjoy reading them, even if I rarely comment. Keep it up!)

  4. Dave

    Nick has already seen this, but for the benefit of anyone else asking the same question, I wrote it up as http://mccraw.co.uk/long-distance-bike-lights/

    :)

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