As far as I can tell, the problem is that sitting on a bike seat and pedaling focuses all of my gigantic bulk onto a few square inches of my body which then oscillate back and forth as a I pedal. I generally get off of the thing feeling like someone tried to split my body in half by making me sit on a telephone pole and putting weights on my feet. It's really not that bad, I think I just need to get used to it. And at least it's very very quiet.