Since your old wheel has bad bearings ...DrkAngel wrote:1. motor rpm x motor sprocket ÷ wheel sprocket = wheel rpm (revolutions per minute)Sunder wrote:Okay, this post is amusing me. I've got to see this franken-bike work. Even better if I get to see the gas motor bolt on.

You can find a 90 tooth sprocket and a 9 tooth sprocket here:

http://www.electricscooterparts.com/spr ... chain.html

You'll get change from $37 for the two of them together. (Have to pay for shipping still though).

3000 x 9 ÷ 90 = 300rpm

2. wheel size" x 3.14 ÷ 12" ÷ 5280' = mpr (miles per revolution)

26 x 3.14 ÷ 12 ÷ 5280 = .00128 mpr (miles per revolution)

3. rpm (revolutions per minute) x mpr (miles per revolution) = mpm (miles per minute) x 60 minutes = mph (miles per hour)

300 x .00128 = .38655 x 60 = 23.19mph

Think I got the math right ... ?

Haven't had coffee yet tho!

Should work and give good efficiency, (modest heat production), ... if you keep above 15mph on hills!

Get a new (or used) disc mountable rear wheel.

A bit of cutting and drilling should let you bolt on the 90t sprocket.

This will make pedal only unreasonably difficult but will supply effective braking on the downhills.