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Old 03-15-2015, 07:14 PM
Hexafluoride Hexafluoride is offline
Motorized Bicycle Newbie
Join Date: Mar 2015
Location: Wisconsin
Posts: 3
Default Gearing and Fuel Economy

Hi everyone! I've had an interest in motorized bicycles for a long time now and I'm finally getting around to building my first one. I'm looking at putting a 4hp engine I have laying around on a Schwinn Meridian tricycle.

From what I've gathered, bikes and trikes aren't very stable at speeds greater than 30-40 mph and a 4hp engine should provide enough power to hit upwards of 50 mph if geared to do so. I want to build this trike for maximum fuel economy and I was wondering how to go about the gearing. Acceleration isn't much of a concern, but the trike has to eventually hit 35ish mph.

I was thinking of gearing the engine so that the trike is going around 50 mph at 3600 rpm. I would never go 50, but if I'm cruising at 35 mph, my thought is that the lower rpms would allow for better fuel economy.

What do you guys think? The big questions I have are: Would the gearing make acceleration impractically slow? Will running the engine at lower rpms result in a non-negligible increase in fuel economy?
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