Okay - the specific concern I'm having right now is two-fold.
First, the teeth on bicycle gears don't appear to have the traditional sort of involute tooth profile I'm used to. . . and bicycle chain is some weird kind of pitch.
I'm wondering if the longer, pointier involute tooth profile of traditional ANSI-friendly sprockets would hinder the 'walking' of the chain to another sprocket. But then, according to this year's rules, wouldn't bicycle sprockets and chain be legal on the robot?
Second - I'm still having trouble conceiving of ways of indexing the derailleur so that it'd only shift one gear at a time. A pneumatic or servo driven system would be easy to implement, but that'd only work for two speeds. What if we wanted more?
Do any simple mechanical solutions exist for semi-accurate indexed movement?