document updated 12 years ago, on Aug 19, 2011
requirements
I want a shifting mechanism that is:
- secure as hell — ideally, the chainline wouldn't move at all
- allows the rear axle / wheel to be as strong as hell
Fortunately, there is another vehicle that has requirements very similar to this:
MOTORCYCLES
OMG, you're crazy. Aren't transmissions heavy, and require a clutch?
Well, it would be smaller transmission than motorcycles have, since there's much less power being transmitted. Perhaps the size of a Rohloff Speedhub.
No, it doesn't require a clutch. No bicycle transmission requires a clutch, because the "engine" (your legs) is able to back off on the power before shifting, which accomplishes the same thing.
Same place as on a motorcycle — inside of the bicycle's main triangle.
Granted, this WILL add a fair bit of weight. You need the transmission mount to be very rigid, to avoid losing power through the chain. So this requires welding two more tubes on the bike.
does it have to be a one-off design? or is there a COTS solution?