Originally Posted by jodypolk
wait, don't you temporarily pedal backwards to shift gears and then continue to pedal forwards?
You are thinking of a kickback hub, which is a form of coaster brake.
I tried to build up one of these last year but never could find a decent way to mount the idler gear without getting someone to fabricate/weld stuff that I didn't have money for. It's still on my list of things to do though, (as well as build up a townie with a kickback)