How to Replace Bottom Bracket on StarTrac 7000 NXT, 6900 Elite and 6800 Pro Bikes
Required Tools: Punch, Crank Puller, 14mm socket Socket wrench, 29mm wrench x 2, Rubber mallet, Green #680 Loctite, Blue #242 Loctite, Torque Wrench (ft/lbs)
- Remove the crank arms from the bottom bracket spindle. Do this by removing the crank arm bolts with the 14mm socket and wrench. Thread the crank puller tool into the crank arm in place of the crank arm bolt. Thread the tool into the crank arm several threads. It may be necessary to use a wrench to tighten further. Now that you have this part of the tool threaded into the crank arm, turn the handle on the tool. As you continue to turn the handle of the tool, this pulls the crank arm off the bottom bracket shaft. Repeat on the opposite side.
- Remove the 29mm nut from the drive side (user’s right) of the bottom bracket.
- Using the rubber mallet, carefully knock out the left bearing by hitting the bottom bracket spindle on the drive side (user’s right). It should take some force to remove the bearings from the frame. *If reusing the bottom bracket spindle, take care not to damage during bearing removal.
- Once the spindle and bearing are removed from one side, use the rubber mallet and punch to remove the nut and bearing from the spindle.
- Use the spindle to knock out the remaining bearing.
- Remove any remaining loctite and clean inside of the bearing housing.
- Apply Green #680 loctite to one of the new bearings.
- Align bearing with the frame and tap the bearing into the frame using the rubber mallet. *DO NOT hit the inner race of the bearing. This may damage the bearing.
- From the opposite side of the frame that the bearing was just installed, insert the bottom bracket spindle into the bearing.
- Apply Green #680 loctite to the remaining bearing and install onto the spindle and into the frame. *DO NOT hit the inner race of the bearing. This may damage the bearing.
- Apply Blue #242 loctite to the 29mm nuts and attach to the spindle. Use the 2 x 29mm wrenches to tighten the nuts.
- Tighten the nuts until both bearings are firmly seated into the frame housing, then back off both nuts until there is smooth rotation of the bottom bracket spindle.
- Check the 29mm nuts to ensure both are tightened to 10 ft/lbs.
- Check installation. Check for any side to side play or looseness.
- Re-install chain guard and crank arms.
- Tighten and torque the crank arm bolts to 30 ft/lbs, **Do Not over tighten the crank bolts. Over tightening can cause damage to the crank arms and/or bottom bracket spindle**.
- Ride the bike under a load and then recheck the crank arm bolts. The torque spec for the crank arm bolts is 30 ft/lbs. Re-torque if necessary. **Do Not over tighten the crank bolts. Over tightening can cause damage to the crank arms and/or bottom bracket spindle**.