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Old 11-05-2008, 12:07 PM
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conradcliff conradcliff is offline
Motorized Bicycle Senior Member
Join Date: Oct 2008
Location: Tampa, Fla.
Posts: 67
Default Re: Your opinion on top speed/RPMs

Originally Posted by HoughMade View Post
You have not figured in how much horsepower it takes to move this combination at speed. If you do not include that, you can gear the up far enough that, theoretically, 1 hp would result in 300 mph- but we all know that will not happen. There is more to it that gearing. Why don't bicycles have 80 tooth front sprockets with 12 tooth rear so we can all pedal at highway speeds? To defeat all the forces, wind, friction, gravity, etc.- you will need closer to 5 hp to get to 50 mph.

With 2.5hp, you can get around 40 mph with proper gearing, but not much more no matter what ratios you plug in. There is just not enough power to get the engine to spin fast enough to get close to 50 mph.
This I know and that was the point of this see just how fast a 2.5HP GXH50 would push me. Now that I have a good idea of that, thanks to your post on the other website I will be able to choose a gearing that at my lowest rear ratio I am only traveling at or around 40MPH at the given RPM range which will give me optimum power throughout the entire gear range.

Thank you so much for your help HoughMade, I think I have the info I needed
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