Re: running vs biking -- In college I was mainly a runner (2.5 hr marathon class), but I also rode my bike a couple of miles each way to class. For spring break one year I tied a pack on my bike and in one day rode 135 miles over the coast range and down the Oregon Coast to visit a friend. That was a long time ago and I can still remember how tired I was by the end of the day. I was really sore the next day. Not as sore as after running a marathon, but pretty sore. The saddle was not my friend. The following day I rode the 135 miles back home. I made it, but I can't imagine doing that daily without a lot of seat time before the trip.