Old 10-26-18, 07:52 AM
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Originally Posted by rhm View Post
Rene Herse and others used to set up dynamo lights with a wire inside the down tube with a carbon brush connection inside the fork steerer tube. Here's a diagram I found with a little help from Google.

More discussion here:
René Herse randonneuse bicycle

Of course today one would use a dynamo in the front wheel, rather than one running on the rear wheel; otherwise the Herse design should work fine. Has anyone on this forum tried this, or something similar? (calling @gugie, who helped with that illustration). Do you have any experience to share? Suggestions on materials, what kind of carbon brush to use, etc?
Rudi, funny you post this, as I'm planning on doing something like this on a new frame this winter. I met Corey Thompson has done this as well, and we discussed it in detail at French Fender Day. @Jmclay has done the inverse - his brush is brazed into the down tube, the contact ring on the fork.*

Corey takes a blind water bottle boss, and uses his lathe to remove the threads and drill a small hole on one end. Here's a pic of the boss before machining:

He makes his own brush out of brass and a spring, encases it with heat shrink insulation, and slides that into the boss. The contact ring is thin brass sitting in a machined plastic piece. This goes right above the headset bottom cup. A wire is soldered to the thing brass ring and heads down the downtube.*

I have a more detailed version of all this from Corey, I'll see if he doesn't mind republishing his email and pictures that he sent me. There's a good chance I'll go up to Tacoma sometime near Thanksgiving for a shop visit - he's 6 miles from the Tacoma train station, so I could do a train-bike thing.*

The few people I know who have done this don't use carbon for the brush. The concern is that it will break easily.*
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