12-18T Single Speed Freewheel Sprocket Gear Bicycle Accessory Flywheel
Bike Single Speed Steel Freewheel Cog 12-18T Flywheel. 1 Freewheel. The smaller the number of teeth, the faster the speed. If the rear flywheel is 16-tooth and you use the 12-tooth rear flywheel, then its speed can be increased by 30%.