Top Speed on my 49cc bike

M

Michael Fox

New Member
I recently clocked my speed on my 49cc bike with a Garmin Forerunner 305 GPS watch. The watch seems to be acurate with several car speedometers I compared. My cheap bicycle speedometer was reading 35 to 40 MPH. The Garmin clocked me between 26 to 27 MPH top speed with a 44 tooth gear. I did an excel spreadsheet calculation and a 44 tooth gear should get 26.14 MPH at 6000 RPM and 30.5 MPH at 7000 RPM. A 30 tooth gear will get 38.34 MPH at 6000 RPM and 44.731 at 7000 RPM. A 50 tooth gear will get 23.0 MPH at 6000 RPM and 26.83 MPH at 7000 PPM. This is based on what I assume is standard crank shaft to clutch shaft ratio and my 83 inch circumference rear wheel. Do you see similar speeds?

How do some 50cc scooters start from a dead stop without pushing off and seem to reach pretty fast top speeds with very small rear wheels and sometimes with two people on them? Do they have some sort of torque converters?
 
Most scooters have a CVT and an engine far superior to your chinagirl 2-stroke - your engine isn't far removed from around WW2 era.
 
Michael Fox said:
Is there any CVT transmissons available for motorized bicycles?
Click to expand...

Not specifically, no. There are members here who've installed engines and CVTs originally purposed for go-karts and pocketbikes tho.

CVTs aren't perfect. They don't lend themselves well to pedal power and they can rob a significant amount of power.

There's always a trade-off!
 
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