Here's the Prob: What is the smallest raduis of an unbanked curve around which a bicyclist can travel if her speed is 18 mph and the coefficient of static friction between the tires and the road is .32? This was the response I got: For the second one: draw a freebody diagram, label all the forces, then use the centripital force equation F=(mv^2)/r to find the radius. Now...here's my question: Thanks, but wait, I'm still a little confused on the bike problem. We need to know the mass of the bike and the rider, and that's something we don't know yet. How do you find the mass? wait...tell me if I'm doing this right..... g=gravity? So to find the mass would you use the equation g=G*me/re^2?? If not...still, how is the mass found??