Old 10-26-18, 05:40 PM
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Originally Posted by gugie View Post
.......... @Jmclay has done the inverse - his brush is brazed into the down tube, the contact ring on the fork.*
this subject really intrigues me... more as a spectator than as a potential participant.
Still, as an electrical engineer who's been making his own dynamo headlights since before there were white LEDs, I have pondered the various methods and technologies.

John Clay had a thread on the Classic Rendezvous list when he was working on his design. His Flickr album is a nice summary of the work, but he was nice enough to write up a proper report. I stashed away a copy for my own records, and have tossed it up on my google drive so that I can share it with others:

I'm not sure what the relative merits are between locating the brush in the down tube vs. the steerer tube. Locating the brush in the steerer would seem to require a significantly larger hole in the steerer. Locating the brush in the down tube seems to require installation when the frame is built, as John Clay did. It would require an unusually large vent hole in the head tube to retrofit a brush into the down tube.

As an engineer, it bothered me that no one has come up with a higher tech means to couple the energy across the barrier between the steerer tube and the frame. It bothers me more to admit that I haven't come up with a good way of doing it either.

Steve in Peoria
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