Assault AirBike, Replacing the Bottom Bracket

This article covers the steps necessary for replacing the bottom bracket on the Assault Air Bikes.

The basics of the replacement apply to the models Classic, Elite, and Pro by Assault Fitness.

This begins at the bottom bracket removal. The pedals and crank arms have already been removed.

Click here for help removing the pedals and crank arms of your bike.

As noted above, the basics for the different Assault AirBike models are the same. The diagram below includes the parts called out in this replacement. It is used as a reference and may not be identical to your model.

Tools Required

• 8mm Wrench
• Bottom Bracket Tool for 20-Notch Cups
• Flat Screwdriver or Allen Wrench

Replacing a Bottom Bracket of an Assault AirBike

1. Working on the left side (from the seated position), remove the three screws from the bottom bracket locking plate (38). You will need the 8mm wrench. Remove the bottom bracket locking plate after the screws (39) are removed.
2. Remove the chain cover (20) on the right side (from the seated position). Click here for help removing the chain cover.
3. Remove the chain wheel (19). Click here to learn about how to remove the chain wheel.
4. Remove the three screws (39) from the bottom bracket locking plate (38) and remove the plate.
5. Install the bottom bracket tool. Place the teeth of the bottom bracket tool into the teeth of the bottom bracket cup. Using the ratchet wrench or crescent wrench to turn the bottom bracket tool, you will turn right (clockwise) to loosen and remove the bottom bracket (21). If removal of the bottom bracket is difficult, it helps to use a crescent wrench, combined with a bolt threaded into the bottom bracket shaft, to hold the tool in place while applying pressure to break the bottom bracket loose. Remove the bottom bracket from the frame.
6. Remove the bottom bracket cup and lock ring from the non-drive side. This is a standard thread. You will turn left (counter-clockwise) to loosen and remove the bottom bracket cup and lock ring. Tap with the flat screwdriver or Allen wrench, on the lock ring to turn it to the left. Remove the lock ring. Install the bottom bracket tool into the bottom bracket cup. Turn left (counter-clockwise) to remove the cup.
7. Install the new bottom bracket (21) and tighten it into the frame by turning it left (counterclockwise) with the bottom bracket tool.
8. Re-install the bottom bracket locking plate (38) with the three screws removed earlier. You will need the 8mm wrench to tighten the screws (39).
9. Re-install the bottom bracket cup on the non-drive side of the bike. You will need the bottom bracket tool. Turn the cup to the right (clockwise) to tighten.

     Tech Tip

   A bottom bracket should not have any excess play or movement during rotations of the axle when properly installed.

10. Re-install the lock ring onto the non-drive side of the bottom bracket. You will tap the lock ring to the right to tighten it with the flat screwdriver or Allen wrench. Make sure the lock ring is rather tight.
11. Re-install the bottom bracket locking plate (38) and tighten the three screws (39) that hold it in place.
12. Re-install the bell crank and chain wheel (19).
13. Re-install the chain cover (20).
14. Re-install the crank arms and pedals.
15. Check bike operation.

This completes how to replace the bottom bracket on an Assault AirBike.