Lighting problems

[carigada]

I was recently showing my Agattu off to a friend and as I watched him cycle away from me the rear light went off. When I got the bike back I found that it cut out every time the bike reached a slow walking pace but came back on when the bike stopped.

Investigations with a multimeter revealed the problem. There was a high resistance in one of the conductors embedded in the rear mudguard. Just enough voltage was getting through to turn the light on and it was then going into battery backup mode. Speeding up sent the light into dynamo mode but not enough power was getting through to light the LED's so it apparently switched off. Slowing down meant it came back on again!

I do frequently check my lights, for example when I stop at a junction. The light always looked as if it was functioning correctly but I was unaware that it turned off as I set off. I have probably been cycling on the dark roads for the last few months without a rear light showing .

This is obviously highly dangerous and illegal as well.

 

[flecc]

These mudguard connections are often troublesome. I think it's best to always ride with two rear lights, adding a second LED light doesn't cost much and makes for greatly increased safety. Here's my Q bike setup, the standard mudguard light and a saddle rim LED strip light for example:

 

[Cyclezee]

Carigada,
I have had 2 broken rear mudguards on my Agattu, but that is another story.
I experienced problems with the rear light wiring and have now bypassed the mudguard with a continuous cable Evans Cycles | Busch & Muller Double Dynamo Cable | Online Bike Shop , the rear light works perfectly now.

J hn

 

[carigada]

Thanks, Aldby,

That's pretty much how I solved the problem, except I used some two core bell wire that I had to hand. I ran some of that along the inside of the mudguard and connected it to the copper rivets so it's pretty much invisible. It does look better without wires running along the frame, I think.

I mentioned this problem mostly as a heads-up to the folks on this forum so that those with a similar lighting system to the Agattu's dynamo powered Busch & Müller setup might want to check to see if they were working correctly.