mitosis said:Use almost twice the energy used per unit of time.
More rapid weight loss than cycling (if you are trying to lose weight).
All good and mostly valid points, but I have to call BS on these two. If you burn twice as much running as cycling, you are not cycling hard enough. If I can ride at LT for one hour vs. running at LT for one hour the calories burned will be close enough to equal. Regarding rapid weight loss I can ride my bike for 5 hours at an easy fat burning pace back to back to back. I need a week to recover from a single 2 hour run, and even if you argue this is conditioning, I will counter it is easier to spend more time on the bike than running no matter what level of conditioning you begin with.