Crank Forces Lets say, for example, a 70 kg person puts 80% of their mass onto on pedal: 56kg. And, for simplicity's sake, the crank arm is parallel to the pedal. The crank arm length on my bike is 170mm or .170m. The radius of my chain ring is .05m and has 32 teeth (this will be important later). A person applying 56kg to the pedal would be putting 549.36N of force onto the pedal. The crank would then apply a torque of 93N onto the chain ring which directly applies that force to the chain itself. Since the chain is not stiff, the force underneath the chain ring is near zero, so all the force that is applied is pulling at the gear cassette...