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Rear dynamo lamps

Discussion in 'Bicycle Mechanics and Repairs' started by Yellow Fang, 25 Jan 2008.

  1. Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    Does anyone manage to get them working satisfactorily? I have a Schmidt dynamo hub on my Brompton. It's brilliant at throwing out light from the front lamp when it's moving, but I can never get it to light up the rear lamp properly. I tried several different lamps, the latest being a Busch & Muller D Toplight with a battery backup. I've given up trying to get a front lamp that stays on when stationary at traffic lights, but I wanted the rear lamp to stay on. Instead all I get is the rear lamp flickering on and off fairly randomly unless I switch it to battery mode, which is defeating the point.
     
  2. Danny

    Danny Legendary Member

    Location:
    York
    Sounds to me like you have some kind of connection or earthing problem.

    I have a dynamo with a pretty basic rear light which usually works fine. Occasionally I get problems which can take quite a while to track down, but are usually due to loose or frayed connections.

    If you have tried everything obvious, I would go and find a good LBS who are used to fitting dynamos and ask them for help in tracking down the problem.
     
  3. Never had any problems like that with my B&M stuff. As Danny says, make sure the lights and dynamo are earthed properly and all the connections are sound. Soldered connections are better than plug in connections.
     
  4. bianco

    bianco New Member

    I know this is completely against the point of your post, but why don't you buy an led battery powered light?

    I've had mine all winter and not had to change the batteries.
     
  5. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    I have got a rear LED as well. It just annoys me that I can't get my dynamo lamp to work properly.
     
  6. P.H

    P.H Über Member

    It's almost certainly a problem with the connections rather than the light itself. Are you using twin wire or a single and the frame for earth? In my experience the latter can be unreliable but decent twin wires rarely give trouble. The coaxial cable is best, will continue to work even if the casing gets damaged.
    http://www.bikeplus.co.uk/cgi-bin/q...ts_seen=10&page=search.html&and=&affiliate_id=

    Also leave it a bit slack, cable doesn't like being stretched.
     
  7. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    I was using the frame for earth. I am not sure what I would connect the earth connector too otherwise. There does not seem to be a spare connector on either the front lamp or the dynamo hub.
     
  8. P.H

    P.H Über Member

    If your front lamp hasn't got a connection for earth it will be using the frame. Clamp one end of the wire either between the lamp and frame or to the metal bracket. The hub to front light is already a twin wire system so no need for extra connections to the hub. Some instructions here, these are for a bottle dynamo, but you'll get the idea;
    http://www.camcycle.org.uk/newsletters/40/article9.html

    It can be a bit of hassle, but once done it'll give trouble free lighting for years.
     
  9. OP
    OP
    Yellow Fang

    Yellow Fang Guru

    Location:
    Reading
    Thanks for your advice. It was an earthing problem. It seems to be working well now, although I doubt for long, as I've only used thin pieces of wire from Maplins and I haven't soldered them on neither. I'll have to get a proper bit of cable at some point.
     
  10. domtyler

    domtyler Über Member

    For cable I found that an old power adapter, I think it was from an electric christmas tree, was ideal, lovely and thick co axial cable. For a soldering iron Maplin have one for about two quid at the moment.
     
  11. andrew_s

    andrew_s Veteran

    Location:
    Gloucester