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Old 10-13-2012, 12:32 PM
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fatdaddy fatdaddy is offline
Motorized Bicycle Elite Member
Join Date: May 2011
Location: San Jose, Ca.
Posts: 1,518
Default Re: what did you do to your motor bike today?

Originally Posted by dracothered View Post
Well I bought (ordered) my pulleys for the primary drive on my bike finally and worked out the sizes needed. The one coming off my output shaft will be a 2.3" which will go to a 4.45" pulley on the jack shaft. This will give me a jack shaft speed of 1808.98 RPMs from an engine speed of 3500 RPMs. Here is the formula I used to get these figures:

RPM1 = RPM of Driver
RPM2 = RPM of Driven
D1 = Diameter or tooth count of Driver
D2 = Diameter or tooth count of Driven

RPM1 * D1 / D2 = RPM2
3500 * 2.3 / 4.45 = 1808.98 RPMs

1808.98 * 14t / 40t = 633.14 RPMs going to a 24" wheel.

Then I used the Gear Ratio Calculator program that has been listed on this forum before to get my final output of 5.53:1 with a top speed of 45.2 MPH. Now I don't really think I will get that top speed, but it would be great if I could.
45 (.2) mph would be great. But if ya just get 40mph out of it, thats plenty fast enough for a bicycle, dont'cha think? 35 or so is fast enough for me, (and I'm just a little crazy.) Good luck with it anyway.
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