I too am considering a cycling switch for the cardio. I run now 3-4 times a week off days from boxing roughly 5 miles. The problem I am having is my knees getting sore. Didn't think I had the proper shoes so I got a v good pair of trainers for it, but I still get quite sore.

Can't really afford a machine for running I don't think and my gym doesn't have one. SO considering trading in the BMX for a bike better suited for training.

Any one else find they have probs. with their knees? I get the knee pains immediately after running and kinda worry about damaging them.