I have a bike with a wheel circumference of 2164mm, I want to buy a motor and want to work out how many rpm the motor must deliver to give a speed of 20 mph.
The way I've worked it out is:
1609 meters in a mile
/
2.163 wheel circumferance
=
743.5 revolutions necessary to travel one mile
20 miles = 14870 revs
/
60 minutes
=
247.8 rpm required
The reason I ask is that I'm trying to work out which one of those 8Fun motors to buy but the ones for the 26" wheel size (which I'd imagine is the only sensible one to fit to a 700c bike) all seem to do around 210 - 220 rpm. Now I've heard that bikes with these motors such as the Ezee Torq can get up to over 20 mph. So how is this possible? Probably my maths completely wrong.
The way I've worked it out is:
1609 meters in a mile
/
2.163 wheel circumferance
=
743.5 revolutions necessary to travel one mile
20 miles = 14870 revs
/
60 minutes
=
247.8 rpm required
The reason I ask is that I'm trying to work out which one of those 8Fun motors to buy but the ones for the 26" wheel size (which I'd imagine is the only sensible one to fit to a 700c bike) all seem to do around 210 - 220 rpm. Now I've heard that bikes with these motors such as the Ezee Torq can get up to over 20 mph. So how is this possible? Probably my maths completely wrong.