The Boost is controlled by a lever on your steer, allowing you to set the resistance as required. The higher the position, the more resistance. Smooth ride feel , Silent , Powerful , Manual resistance control , Enables virtual power , Handlebar lever , Dual material roll , Resistance roll 30 mm , Actual flywheel , Foldable , Easy to carry , Easy to set-up , Suitable for power workouts , Suitable for interval training