Why Scooters Have No Gear Lever
Two pulleys, one belt and a set of rollers that slide outward as you speed up.
Read the full teardown
How a Scooter’s CVT Changes Speed Without Gears
A scooter’s CVT uses a V-belt between two pulleys whose halves can slide closer or further apart, changing the size of the circle the belt runs on. Weighted rollers push the front pulley closed as engine speed rises, a spring pushes back at the rear, and the ratio changes smoothly with no gears to shift. A centrifugal clutch lets the engine idle while the scooter stands still.
Transcript
Twist the throttle. No clutch lever, no gear lever. So how does it shift? Let's cut it open. The engine spins a pulley full of rollers, just a few grams each. Rev harder, and they fly outward and squeeze the pulley shut. The belt climbs up front and sinks at the back. A gear change, with no gears. Just twist the throttle.
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