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Friday 3 December 2010

Bottling the Yuba

In July I added a dynamo lamp to my DL-1 and loved it. I was somewhat constrained when it came to choosing a lamp because I wanted something which fitted in with the classic look of the bike. After buying a set of AAA batteries for my front Yuba lamp I decided that I didn’t want to keep buying batteries anymore, I wanted a permanent set-and-forget system like on the DL-1. This time I would be less concerned with aesthetics and able to take advantage of modern-looking LED dynamo lamps.

A hub dynamo was not realistic due to the only reasonably affordable ones compatible with disc brakes being made by Shimano who use a proprietary system for mounting the rotors on the hub (although it is proprietary, it also has some advantages). This would have meant replacing my rotor as well as the front hub, spokes and buying a lamp, at which point the cost became prohibitive. A recent post on Lovely Bicycle! combined with Ian’s positive experiences with the bottle dynamo on his Gazelle inspired me to give the bottle dynamo a chance.

Many people in the UK and in North America have negative associations with bottle dynamos, but both dynamo and lighting technology have progressed a lot, modern bottle dynamos are more efficient and modern LED dynamo lamps can do more with the energy you provide.

I chose the Nordlicht 2000 dynamo, available from Hembrow’s store Dutch Bike Bits. It seemed like a good trade off between quality and price, the roller is rubber and able to run on the rim of the wheel or the tyre itself and replacements are readily available (including a larger wheel for faster riders). The dynamo itself came with no instructions whatsoever, but a bit of playing around with it revealed that the dynamo has a proper – connection rather than using the frame. The two prongs on the bottom are the terminals, they are spring-loaded and have a small hole in them which is revealed when depressed. This allows you to insert a wire and then release the prong to secure the wire.

The lamp I chose is a B&M Lumotec Lyt Plus (includes standlight). Having found the Lumotec Retro to be impressively bright already, the 50% higher rated light output on this model caught my interest. Being German, this lamp conveniently comes with a built in reflector. Once again, information was not particularly forthcoming. This lamp is rated at 2.4W leaving 0.6W for a dynamo rear light. There are connectors on the underside for both the dynamo itself and the rear light. The lamps is supplied with a wire to connect to the dynamo.

Sadly, the dynamo bracket I ordered was not as advertised, described as fitting to the left cantilever boss it in fact fits to the right (drive side) cantilever boss, causing problems with my left-fitting dynamo. Rather than getting it replaced, I decided to use a Birmingham screwdriver to make it fit on the left side. I will eventually replace it with a fork-fitting clamp so that I can run the dynamo on the rim to reduce drag at higher speeds.


The reflector works well.


The reflective tape shows up well on the side-rails too.


I wrapped the wire from the lamp around the hose line of the hydraulic disc brake (probably not the most common combination of bike technologies), and the bodged bracket.


The current set up is not particularly elegant, but the Yuba Mundo isn’t really about elegance anyway. When the replacement bracket comes, I will run the dynamo on the rim and tidy up the wiring a bit.

After installation I took the Yuba out for a test ride on the Fallowfield Loop. The Loop is great for these kinds of tests because it is completely unlit, plus the snow hasn’t been crushed into ice by cars.

When engaged, the dynamo makes a low whirring noise which is not overly distracting. The fact that the pitch changes with speed is actually quite useful for judging speed when darkness obscures the odometer. The level of illumination provided even at low speeds (10 km.h-1) is impressive. By around 15 km.h-1 the lamp is around three times brighter than my Revolution Vision lamp and probably twice as bright as my Lumotec Retro lamp. The shape of the light cast on the ground is slightly rectangular (tall rather than wide), which is actually quite useful. It was almost like riding with a pimpmobile directly behind me. The light provided my the Revolution Vision LED lamp is slightly too blue for my eyes and I was concerned that the light from the Lumotec Lyt would be the same. Thankfully it is actually very white, making it easier for me to see irregularities in the road ahead. Unlike the Lumotec Retro, the standlight feature uses the same bulb as the main light (albeit at reduced brightness) and so benefits from optimal positioning within the lens producing more useable illumination.

As for drag, I can’t really give a verdict on that yet. The Yuba is currently set up for snow; lower saddle, lower tyre pressure and the slowing effect of the snow itself means that I can’t make a fair comparison. I’ll provide an update after the snow has cleared.


  1. I've had a cheap £10 Decathlon dynamo on my Nexus for a few weeks now. It drags like a bitch and makes a right old whirring racket, but it does a fantastic job :-D It's got me thinking about a dynamo drum braked hub at somepoint in the future, but I'll have to have a little clearout first.

  2. Great stuff - especially the mention of the Birmingham Screwdriver! Never heard that before but am a great believer in the therapeutic qualities of using one ;>D

  3. @Jim

    The Sturmey Archer X-FDD hub is a really nice drum/dynamo combination. I have used mine on two bikes in two different sizes of wheel. I also have the non-dynamo version (X-FD) and other than the lack of electricity, I notice no difference in performance. The Shimano one is rumoured to have the same electricals inside (made by Sanyo I believe). The IM70 roller brake would be compatible with any of their roller-brake dynamo hubs and is supposed to be really very powerful. It does add to the cost though.


    Birmingham screwdriver is something I heard on QI, it dates back to the days when things were still (perhaps oafishly) manufactured in the UK. Very relaxing to use one


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