what throttle cable should i use? the r1 ones a wee bitty too short, would a sierra one do?
cheers

Have you considered using a push bike brake cable?? Cheap and readily available.

I used pushbike brake cable bought by the meter with the outer and somr fittings for both my throttle and return.
Cost about a fiver in all.

is it necessary to have a return cable?

cheers

The throttle mechanism is spring loaded but extremely light so you will want to fit a return spring to your pedal but you wont need a return cable