The best multi-speed transmission

[Gabe]

One advantage that nobody has mentioned for a lightweight transmission is rotational inertia. Force must be applied over a longer period of time when the wheel (in this case the gear) has greater mass. On startup this means that batteries will experience a current surge for a shorter period of time. Less weight also means faster acceleration.

This year was the first year we built a custom two-speed transmission. It is a ball-shift with a 1:9 and 1:3 ratio gearing with a single Minibike motor. See here: http://www.chiefdelphi.com/forums/sh...ad.php?t=55786
We learned from our stupid mistakes, like you never calculate from unloaded speed (oops), and look at power ratings before choosing motor (oops again). Although an impressive achievement, it has weight issues that could have been addressed by using smaller diametral pitch gears (I'm thinking 32 DP). We learned alot from our experience, and expect to see big improvements next year.