What’s Wrong with this Picture?

bottle dynamo
It’s a genuine question…

Regular readers of this blog will have guessed that, as soon as David Hembrow had sent me a replacement bracket for my dynamo, I would promptly put it all on the kitchen table next to some spanners to remind me to fit it and then leave it there until it was too late to fit it to the bike the next time I needed a light. And that’s exactly what happened. I mainly need my lights to get back from choir and so for the last few weeks I’ve ended up having to use a spare battery light as a replacement, and thinking I definitely, definitely will fit the bracket before choir rolls around again the next week, and by ‘fit’ I mean ‘get the other half to fit for me’, obviously. Up until now, a battery light has been fine in the dusk after choir but as the weeks pass and the nights draw in, I knew one of these days I was going to get out and find it properly dark and then I’d really want my dynamo light going again.

And so today, rather than tidy up around the replacement bracket and the reminder spanners again, and knowing that it would be getting pretty dark this evening, and having a spare half hour on a sunny afternoon, I decided to get the bike out and have a go at fitting the damn thing myself. After all, it was a fairly simple thing and I should be capable of it and all that (although, to be honest, whenever I hear someone banging on about how one of the joys of cycling is having a machine that anyone can understand and fix themselves, I know they have not seen me try and fit a bell to take an example at random). After a couple of false starts – do you know how hard it is to find a black washer when you have dropped it on some rather desperately unweeded cobbles? – I managed to work out which way round to attach the dynamo to the bracket by dint of trying all the ways round in which you don’t attach the dynamo to the bracket, attached the bracket to the fork in roughly the place where it was before going by the scratches in the paint, took it out for a test ride, retrieved the dynamo from between my spokes when it fell off having not been tightened enough, tightened it enough and ta daa! One fitted bracket. Simples.

It’s got me down to the village and back without skipping and without feeling as if I’ve got it on too tight and more importantly while actually generating some light. But I still have a sneaking suspicion that I’ve managed to put it on upside down and inside out or backwards. So I leave it to all you geniuses out there to let me know what’s wrong. Before I find out the hard way…

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7 Responses to What’s Wrong with this Picture?

  1. livinginabox says:

    I’m not a fan of bottle dynamos, I prefer the hub-type. I am certainly no expert regarding these. I immediately run into the problem of describing 3-D objects in words. There is also the problem that when I’ve used bottle dynamos, they were on the rear stay. Fork-mounting anything introduces the potential for that thing vibrating loose and getting into the wheel and consequently locking the wheel causing the rider to somersault suddenly and violently over the handlebars, (I once managed to do this with a fork-mounted light, when I was much younger and as tough as old boots. With many more ‘years on the clock’ I doubt I’d find it quite so trivial nowadays). I was lucky, my somersault was without ill-effect, plus fortunately the driver following behind was able to stop.

    Things to look for are anything that causes hazard, inefficiency or loss of function.
    Is the roller axis parallel to a radius of the front wheel? (ignore the inward tilt of the dynamo). If this isn’t the case, the roller will skid, slip and wear both the roller and the tyre sidewall, it will also wear you out.
    The dynamo bracket needs to be as tight as possible. This involves the use of the correct-sized driver / spanner, otherwise the nut / screws etc. will likely be damaged. Some kind of waterproof, grippy resilient stuff is needed to fit between the bracket and the fork. A sheet of thinnish rubbery material is ideal. The bracket needs to be as tight as possible. A thread-lock adhesive is a good-idea to prevent it becoming loose (Loctite perhaps). I use thread-lock on most of my bike screws and fasteners. Be wary, there are semi-permanent and permanent grades, use the semi-permanent grades, (the permanent grades are a devil to undo, yes, I found-out the hard way).
    Electrical, some dynamos use a screw that pierces the paint on the frame for electrical connection. Something to be wary about with Aluminium forks (might cause cracking). I realise your forks appear to be steel, but someone might have come hear via a search engine and their bike might have Aluminium forks.
    Of course, you could ask someone who knows what they’re talking about.

    Suggestion for the future. Take a photograph before-hand. Save it in your bicycle maintenance folder.

    Good luck. I recommend a daylight test-ride to check that all is well.

    • livinginabox says:

      By the way the soundtrack of the video is utter crap, but what do you expect?

      My money is on a loose side-wall dynamo jamming the front wheel.

  2. disgruntled says:

    This (plus discussion on twitter) pretty much confirms my suspicion that the whole joy of the simplicity of bike maintenance stuff is so much baloney …

  3. welshcyclist says:

    Dark evenings already, as well as dark mornings, which reminds me I have to recharge my headlights after my commute home this morning. Pitch black mornings and evenings on the horizon, great joy! Where did summer go?

  4. disgruntled says:

    I know – but it was a brilliant summer at least

  5. […] of transport, I should probably be able to sort it out when it went wrong. And so I had a go at replacing my bottle dynamo All By Myself and was quite pleased to discover that I had apparently done it more or less right […]

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