BBR Tuning 2-Stroke/4-Stroke Motorized Bicycle Free Wheel Pull Start Heavy Duty Axle Kit &ndash; Gas Bike Rear Axle Upgrade Free Wheel Heavy Duty Axle Kit Bicycle Engine Replacement Motorized Bike Those old rag clamps can loosen and tear, and metal clamps can put a little too much weight on your wheel. With this heavy duty axle your wheel and rear drive sprocket are one unit, and stronger than ever The drum brake included with have you stopping on a dime, while the rear sprocket is mounted sturdily and tight to the wheel Note: This kit is a wheel building kit, so it's recommended that you have advanced bicycle wheel building experience or access to a professional builder Made for pull-start 4-stroke bicycle engines and modified 2-strokes with pull-starts. Compatible engines include the Flying Horse, Skyhawk, Mega Motors, and PK80 engines