Originally Posted by

**cazury** Hi there. I'm having a bit of trouble with a word problem.

The question asks that you develop a formula predicting the velocity in km/h for a bicyclist

which is dependent on three independent factors

- the speed at which the cyclist pedals to turn the front gear (in rotations per minute)

- the gear ratio from the front gear to the rear wheel (ratio between #teeth on the front gear compared to #teeth on the rear gear)

- size of the rear wheel (diameter of wheel)

I thought that the formula would be something along the lines of

V=f*(a/b)*d***pi**

where f=rpm of front gear

a/b = ratio of teeth on front gear to back gear

d = diameter of wheel

But part b asks:

if a cyclist pedals at 50rpm with 42-toothed gear on the front, a 14-toothed gear on the back, and a tire with a diameter of 26 inches, how fast will the cyclist travel in km/h?

When i subbed these values into my equation I got an answer that I figure couldn't be right (0.00165km/h)

Can anyone shed some light for me?

Thanks a lot