Originally Posted by
Jmclay
It's concern about breaking carbon brushes while inserting and removing the fork. Electrically there is no doubt they'd be superior.
The commercial carbon brush unit that I modified for prototyping was so overhung that it would have been easy to break; or difficult not to! I considered drilling the center of the brass brush and soldering a round carbon brush in the cavity. Haven't done that but might give it a try on a test piece sometime.
aahh! Seems reasonable, and probably one of those things that becomes much more obvious once you move from the paper design to actual hardware.
Could it be addressed with additional parts that would provide ramped or gradual transitions where the tube/assembly radius changed? Might have to tape over the threads for the headset locknut too.
Alternately, it could use some sort of mechanism to retract the brush when the fork is installed or removed. The Herse had something like this, didn't it? With a down tube mounted brush, this would get tricky! Maybe have to tie a string to the brush and let it dangle out the vent hole in the BB shell, allowing you to pull on the string to retract the brush?? This idea might need a bit of refining, of course.
Steve in Peoria