The flywheel belt drives our high-speed steel flywheel inside the rear roller via a pulley on the middle roller. The belt is designed to run continuously at over 1000 Watts with transient capability up to 3000 Watts. When properly installed and tensioned, the flywheel belt should last for tens of thousands of miles. We use a black polymer guard to minimize belt breakage, but they may break if you ride on them. If you need to replace a flywheel belt, it can be changed in minutes using a hex wrench. Please refer to our User Manual for step by step instructions on replacement and tensioning.