Quiet reliability.
Using a belt means no lubricant is needed. So you can ride to work wearing bleach-white bell bottoms, if your dress code allows. You can also carry it up on your shoulder into that tiny upstairs apartment.
The belts we use aren’t your typical rubber band, they’re a state of the art design incorporating carbon fiber. This means no adjustment, as the belt will not wear out or stretch like a metal chain.
It’s also quiet. Too quiet.