Waterproof Electric Bicycle Conversion Kit 48V 250W Rear Drive Rotating Flywheel Item Type: Electric Bicycle Conversion Kit. Number of Magnet Poles: 20. Motor Structure: Gear Motor. 1 x Thumb Throttle. Open Size(mm): Rear Motor: Approx. Speed Setting: 1-4.2V. Mose Tube: 6 Tubes.