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not resolvedHi
I've got a hub dynamo and Busch and Muller lights - rear with LED and front with halogen. The rear hasn't worked for ages, but I can tell if it's dead or a wiring problem. The front bulb doesn't work but doesn't visibly seem to have blown, but the 'stand light' still works so there's power from the dynamo.
Any recommendations for an Edinburgh bike shop that could fix this? I don't want to buy stuff off the web and then find it's the wrong bit!
Thanks
BikeTrax on Lochrin Place sell dynamo lights, so might be prepared to frown at your current setup.
"The front bulb doesn't work but doesn't visibly seem to have blown, but the 'stand light' still works so there's power from the dynamo"
Do you mean there's a separate bulb for the standlight function or that the bulb only glows when the standlight capacitor is charged, not whilst the wheel is turning?
"if it's dead or a wiring problem"
The rear is probably supposed to run off 6V, so test it with a couple of bits of wire taped up to a couple of AA cells (rather than a PP3), starting with the terminals where the dynamo wires connect to the light. Maplin sell spade terminals and bits of wire for possibly slightly less than an official replacement dynamo wire.
I think Martin at http://www.wheels2wheels.co.uk knows something about dynamo systems
I've spent a fair amount of time putting a multimeter on motorcycle electrics. The cause of almost all intermittent woes is corrosion in wires and, particularly, earth connections. You find them by exhaustive measurement of all bits and bobs.
If you're in the south side and want me to put the meter over your bicycle electrical components just drop me a PM and we'll see what we can do.
Spin the wheel and touch the tail light wires together. If the hub slows down, the wires are OK. More likely I suspect it will keep blithely spinning = new wires needed.
Stick to B&M and all the stuff is freely interchangeable so you can easily do it yourself, I'm sure there will be plenty of shop recommendations too though.
Eliminated a few problems in past. Usually wiring of course. if lights have spade connectors then easy to wire up a rough new bypass rear line just to check out and prove old wiring is the problem
I also have some extra lights to eliminate the broken light scenario.
Have also had duff dynamos - not supplied to customers luckily. Rare but does happen if you see enough. Mostly wiring up new stuff here but can look at.
We could look at it for you. Andy has a similar system himself and we have done some dynamo repairs in the past.
Iain
Eastside Bikes
Still can't decide whether to dig out my multimeter and some batteries and try to track down the problem or go along to one of the shops suggested - but many thanks for the pointers!
I was aware Biketrax did B&M stuff in the past - in fact it's where my bike with lights and dynamo came from a while back - but their website has zero B&M now, so I'd assumed they've dropped it.
ocbert, I'd suggest the issue with the front light is the halogen bulb has gone. I have just had exactly the same problem on a B&M Lumotec plus: main beam off, stand light working. Got a spare bulb from Eastside Bikes this afternoon, fitted it, hey presto! One working front light.
As for the rear, tricky to say. Try replacing the wiring to that light with some copper audio speaker cable. That may do it. If not, light is probably kaput.
Over many many years the problems for me were - in order:
1) Corrosion or physical damage within the light meaning that the bulb wasn't connecting to the bits it was meant to connect to (fix with scraping, bending, and stuff squeezed into gaps to push things together)
2) Corrosion or dirt between wires and where they connected to the light bodies. Fix with scraping, bending, and squeezing things into gaps to push things together - and occasional bits of solder and insulation tape.
3) Slipping dynamo against tyre (fix with gluing something less slippy to the rotating bit of the dynamo body).
I eventually found the ideal (if somehow defeatist) solution, which was to give up and carry much lighter and brighter LED lights. In many ways this is a shame. For many many years I swore by dynamo lights - they were always there, difficult to steal, and brighter than the alternatives. But now I have lights I can remove in a moment, which are small, light, and MUCH brighter than a dynamo - and yes, one of them has a lovely wide beam just like the dynamo.
Maybe more helpfully, my tips for fixing are probably to use the multimeter - disconnect everything, test the resistance of everything to check connections, test for power from the dynamo with some kind of direct connection to it (multimeter or wires straight to a bulb), check the bulb with a battery or again with the multimeter. Connect everything back together bit by bit, testing as you go. It'll fix it... it's a simple process (does electricity flow from A to B or not)... you'll know where the problem is for the future... but it does take time. Every time I tried to shortcut this process I got in a muddle - when I did it this long way I always worked out what was wrong. Don't forget if you start testing for connections that there's a connection right through the dynamo itself - that used to get me confused - indeed I may still be confused, but I think I'm right.
Hub dynamo LED front and battery LED rear is possibly the best of both worlds. Minimal wiring makes problems much easier to diagnose and on my main bike setup are normally restricted to surface corrosion on the wires where they contact the dynamo. My winter bike has a rear lamp connected to the dynamo via the front lamp; with the benefit of hindsight it's more trouble than it's worth.
It must have been a right pain when dynamo lights had a bulb in them!
Ours seem pretty reliable - three bikes with dynamos (two with wired tail lights) and no issues even after several years on the commuters, which is quite a bit of mileage.
Three different brands of dynamo as well, Sturmey, Shimano and Shutter Precision (which is my favourite, but doesn't get as much use as it's on the nicest bike).
I just swapped the front light on my winter bike after three years because I fancied a change - I had the original one in 2010 because I remember doing a few audaxes that year when I first got hold of it.
I've never considered using the multimeter - spade connectors and decent wire to start off with seems to do the trick. Could just be good luck though, three bikes is a small sample size regardless of the mileage they do?
The Lumotec plus has been mounted on the Raleigh for at least two years, not used absolutely every day but ridden several times a week on average. Bulb suddenly went recently, not a bad innings considering so cheap to replace. Spare bulb is only a quid. Easy to fit, too.
LEDs certainly last longer, many are brighter too now. But halogens are quite inexpensive.
@Dave - don't forget Schmidt Original Nabendynamo, probably on a par with SP.
And then bottle dynamos (from for example Busch and Müller).
I think there may be other Chinese cheaper dynamos too, although I'd probably stick with the brands for the simple reason that rebuilding a hub (in particular) is probably enough hassle to pay for the (perceived) reliability offered by a known brand.
Robert
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