BMX bicycles employ a freewheel in the rear hub that is aptly named for its function. The freewheel allows the rear wheel to rotate freely when the rider stops pedaling. When the rider engages the pedals, cogs on the freewheel lock into place in the hub, which turns the chain sprocket. Freewheels are subject to wear over time and need to be replaced. In addition, the freewheel can be changed when a different gear ratio is preferred. Changing freewheels is not difficult to do. The change-out requires a couple of everyday wrenches and a special tool that's designed for freewheels.
Step 1
Use an open-end wrench to remove the clip that holds the coaster brake to the rear frame arm. For hand brakes, remove the brake assembly from the frame with an open end wrench. Turn the bike over and balance it on its handlebars and the seat.
Step 2
Loosen the nuts on the rear axle using an open end wrench. Slide the rear wheel forward in the frame arms to slack the chain. Lift the chain off the rear sprocket and remove the rear wheel from the bicycle. Let the chain hang on the front sprocket.
Step 3
Lay the rear wheel on a workbench with the freewheel facing up. Position the freewheel remover tool onto the freewheel. Replace the axle nut on the threaded axle and tighten it by hand to hold the remover tool in place.
Step 4
Use an adjustable wrench and turn the remover tool counter-clockwise to loosen the freewheel from the hub. Set the wrench aside and remove the axle nut. Rotate the freewheel counter-clockwise and remove it from the hub.
Step 5
Apply a thin layer of all-purpose grease to the hub threads. Start the new freewheel into the hub by threading it in a clockwise direction. Tighten it by hand.
Step 6
Replace the rear wheel into the bicycle frame. Start the axle nuts on each side of the wheel. Loop the chain over the rear sprocket and pull the wheel away from the front sprocket to tighten the chain to 1/2-inch deflection. Tighten the axle nuts.
Step 7
Reinstall the hand brake assembly onto the frame, or reattach the coaster brake clip to the frame arm. Turn the bicycle upright. Ride the bicycle to tighten the new freewheel into the hub.
Tips and Warnings
- Slide a short length of pipe over the handle of the adjustable wrench for leverage to loosen the freewheel.
Things You'll Need
- Open end wrenches
- Freewheel remover tool
- Adjustable wrench
- Axle grease
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