what pinion?
 

im noob to gearing either though ive been into the hobby for years and years... just 1 quick question... i got a e-revo with hobbywing 80A esc and a 9xl motor im going to use 4 cell A123 battery.... what pinion should i use ? i got a 17 tooth one on the way but is that even close to what i should use? sorry if this sounds like a (not again a darn noob question) haha.. i promise i wont be bugging much more than this... my main use is bashing around with my kids so speed is not the most important thing mainly backyard bashing and some street runs...
Pete

Use this :

http://scriptasylum.com/rc_speed/_solver.html

Depends on Spur but 17/54 will give you 25 - Normally one targets for 40...

Differential Ratio: 2.8461538461538462
Transmission Ratio: 1.8333333333333332
Additional Ratio: 1
Spur Tooth Count: 54
Pinion Tooth Count: 17
Battery Voltage: 13.2
Motor KV: 1853
Tire Diameter (inches): 5.8
Top Speed (MPH): 25.4635 MPH

yea so maybe ill grab a bit bigger pinion on next order.... thanx for the help bud.... cheers
Pete

anyone up for a trade? i got brand new 5mm 32p pinion gear 17T (novak #5157) also i got brand new rc monster hardened steel pinion gear mod1 14t.... i would trade for as big as possible 32 pitch pinion... both are 5mm bore and pinion traded needs to have that too

i would give both if needed