heh.

To balance a bike you have to be able to steer.

If the front wheel is spinning, you can steer. If it is not, you cannot steer.

There are two drums in the back to keep the bike from hopping over the front or rear of the rollers.

If you take off the belt, you won't be able to ride them.

If you have just two drums, you'll probably roll off the drums before you can pedal.

Smaller rollers deform the tire more and increase rolling resistance.

cdr