well I'm just going to put my $.02 in. The reason that you ride to lose weight is not to lose it on the ride but to make it so your body utilizes the blood better and burn calories faster when not riding. you will burn off a lot while ridding but after a while you will get a point that your body will burn more calories then before. When riding, you will build muscle and also make new paths for blood to go through. This makes your metabolism rise. So in other words when you word out you do it not for the immediate lose but to make it so your body will burn off more calories while doing nothing but walking.
hehehe think thats right (this is from last years health class!)
Jared