If you’re the type of person who is trying to figure out how to make riding your bike even more challenging, PowerCranks (www.powercranks.com) is right up your alley. What does it do? PowerCranks puts a one-way clutch in each bicycle crank, making the cranks independent instead of being locked at 180 degree opposition. This simple change forces the rider to pedal in circles by pulling up on the backstroke. They can be mounted on your bicycle or stationary bike so the user can get...