Gearing For RB5

[Dhami1]

Hi guys, im looking to run my rb5 for the first time this weekend at dudley. Got a friend to help me put all the electronics in yesterday,im not so good with the soldering - thanks butch!!

here's what i have:
Nosram Matrix ISTC Esc
Orion 10.5 and 7.5 Brushless Motors
Lipo Cells
48dp 78T spur

Ive decided i should start with the 10.5 motor, just need a little advice on gearing now. we've just installed a 28T pinion for now.. and this seems fine to me (tried it in the back garden)

what pinion should i be using..? am i in the right area using the 28T on a 10.5 motor?

Thanks in advance
Gurdeep

p.s. anyone else using the rb5 at dudley tomorrow?