Sportsmith Blog
26Jan/110

How to Remove and Replace the Bottom Bracket on an Indoor Cycling Bike

Following is a basic guideline of removing and replacing the bottom bracket on an indoor cycling bike. Due to the different brands of indoor cycling bikes and designs for bottom brackets, the following should only be used as a guideline. If any of the information is not exact to the bike being serviced, refer to the service manual or call Sportsmith for further help.

Common Tools Needed:

  • Phillips Screw Driver
  • Set of Allen Wrenches (standard and metric)
  • Bottom Bracket Tool
  • Cotterless Crank Puller Tool
  • 9/16” Socket
  • Ratchet Wrench
  • Pedal Wrench
  • Crescent Wrench

You will begin by removing the outside belt/chain guard by using either or both the Phillips screw driver and Allen wrenches. It may be necessary to remove the drive side pedal (using the pedal wrench) in order to completely remove the outside belt/chain guard.

Once the belt/chain guard is removed, you will need to remove the belt/chain. If the unit is belt driven, you can simply “walk” the belt off the pulley by pushing the belt to the outside while turning the crank backwards. **CAUTION: PINCH POINT ** If the unit is chain driven, most use a continuous chain that can be “walked” off the sprocket just like the belt. **CAUTION: PINCH POINT ** Some chains may use a connecting link and can be separated at the connecting link to remove the chain. The connecting link is different in appearance from all other chain links.

Now it is time to remove the crank arms. How to Use a Cotterless Crank Puller Tool

It works best to place the bike upside down for best leverage to remove the bottom bracket. (If placing the bike upside down, ensure proper seat adjustment for best bike balance.) Begin removing the bottom bracket from the drive side of the bike. This side has a reverse thread. You will need to turn right to loosen and remove the bottom bracket. 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 to loosen and remove the bottom bracket. (If removal of the bottom bracket is difficult, it helps to use a crescent wrench in combination 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. Remove the bottom bracket cup and/or lock ring from the non-drive side of the bike. This is a standard thread. You will turn left to loosen and remove this bottom bracket cup and/or lock ring.

Install the new bottom bracket from the drive side and tighten flush to the frame. Install the bottom bracket cup and/or lock ring to the non-drive side and tighten.

Re-install the crank arms and pedals. Make sure the crank arm bolts are tightened to the proper torque. If unsure of proper torque specs, refer to the equipment service manual or call Sportsmith.

Re-install the belt/chain onto the pulley/sprocket. If belt/chain was “walked” off the pulley for removal, it can be “walked” onto the pulley/sprocket by placing the belt or chain along the bottom of the pulley/sprocket. Carefully, turn the crank arm forward while lifting on the belt/chain. **CAUTION: PINCH POINT ** Continuing turning the crank forward until the belt/chain is in place.

Re-install the outside chain guard and test the unit. Ride the bike without tension and test with tension. Ensure functionality and feel of the ride. Make any adjustments if necessary.