If a bicycle is traveling at 20mph?

T

thinktankthing

New member
If the wheels are rolling at 20mph what rpm are they running at, NOT at the crank but at the wheels? Let's say it is rolling down a hill at 20mph without pedaling.

There has to be a way to determine this without a bike. What do you think?
 
You need to know the size of the wheel.

small wheel, high RPM, large wheel, small RPM.

I'll put in a number, you can adjust it. Say diameter is 1 meter.
20 mph = 8.9 m/s

diameter of 1 meter, radius is 0.5 m and circumference is 3.14 m

every time the wheel goes around, it travels 3.14 meters, per rev

8.9 m/s / 3.14 m / rev = 2.83 rev/ sec

2.83 rev/ sec x 60 sec/min = 170 rev/min

.
 
Back
Top