But, a DF rider can't spin standing. So climbing is closer to comparing a mashing DF rider and a mashing bent rider. In both cases most of the power is produced by simple leg strength (or in the DFs case gravity) pushing on the pedals in more or less a straight line. The only thing controlling that line is the curve caused by the crank arms. BTW, the machine I use in the gym at work very closely mimics my position on the bike, so I am building the same muscles I use to push the pedals. An example of how this does make a difference is a hill I hit last night. We were on a bike trail I had not been on before. It goes under a bridge, makes a hard left and before you is a steep, hundred foot long hill. I was in way too high a gear and never would have made it up the hill six months ago (before spending every lunch break in the gym).