Hey chris, I have never heard about/seen the exercise rollers but it sounds like a great idea! It's perfect for building up wheeling strength and endurance while at home. Hopefully someone knows more about these
If I'm thinking what Chris is thinking, it's like a car dyno! You just setup on the roller and wheel on it but you don't go anywhere because the wheels are spinning on the roller - similar to car dynos.
cbdives, they're like these! There's other setups that you can get, for example one company in the UK has a set that has an electronic distance readout as well. They're essentially exactly what DJ said!