I've done more running than riding over the past several years primarily because I did not have a good place to ride. I just had a spinal fusion on my neck, and with three levels of fusion there now, I am afraid to run very much because of the constant jarring with every footfall. I just bought a bicycle and have started riding it. I plan to really step up the amount I ride as soon as I am out of the neck brace which should be this week.