Eccentric Bottom Bracket Bearing Change

This issue may be covered by warranty

This issue may be covered by your Booda Bike 2-year warranty. Many common problems, however, can be fixed quickly with the troubleshooting steps below. We recommend trying these steps first, especially if the bike is otherwise safe to inspect.

If you would prefer to start a warranty request, or if you are unsure whether the issue is safe to handle yourself, contact Booda Bike service and we will be happy to help.

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Eccentric bottom bracket service video for Booda Bike gear hub models.

Changing the eccentric bottom bracket bearings is advanced service work. It requires removing the rear wheel, releasing the shifter cable, removing the crank, opening the eccentric bottom bracket, replacing the bearings, and then reassembling the drivetrain and checking the shifting.

Applies to

This guide applies to Booda Bike gear hub models with an eccentric bottom bracket.

Tools and parts needed

• 15 mm wrench
• 10 mm Allen key
• 4 mm Allen key
• torque wrench
• hammer
• straight wooden plank
• new eccentric bottom bracket bearings
• bearing adhesive

Before you start

Before removing the eccentric bottom bracket, mark the position of the non-drive-side eccentric bottom bracket cap and the frame. This lets you return the eccentric to the same position during reassembly.

Step 1: Remove the rear wheel

1. Shift to the highest gear.
2. Turn the shifter unit clockwise to loosen the shifter cable.
3. Unhinge the bolt on the shifter cable from the shifter unit.
4. Loosen the gear hub axle bolts on both sides using a 15 mm wrench.
5. Remove the rear wheel.
6. Pull the cable out from the shifter unit cable hook.

Caution

Keep the belt clean and avoid twisting it. Do not force the wheel out if the belt, cable, or axle is still under tension.

Step 2: Remove the crank

1. Loosen the drive-side crank axle bolt with a 10 mm Allen key.
2. The bolt is tightened strongly from the factory, around 54 Nm.
3. Remove the drive-side crank arm together with the spacer.
4. Pull out the non-drive-side crank arm with the axle.
5. If it is tight, move it gently while pulling.

Step 3: Open the eccentric bottom bracket

1. Loosen the 3 bolts on the non-drive-side eccentric bottom bracket cap with a 4 mm Allen key.
2. Remove the 3 bolts.
3. Remove the non-drive-side cap.
4. Remove the inner plastic tube.
5. Remove the drive-side cap.
6. Remove the dust caps from the eccentric bottom bracket bearings.

Step 4: Remove the old bearings

1. Knock out the old bearings from the inner side of each cap.
2. Clean the bearing seats before installing the new bearings.

Caution

Do not reuse damaged bearings. If the caps, bearing seats, dust covers, or crank axle are damaged, stop the work and contact Booda Bike service.

Step 5: Install the new bearings

1. Apply bearing adhesive to the inner surface of both eccentric bottom bracket caps.
2. Push the dust covers into the new bearings.
3. Insert the new bearings evenly into their places.
4. Place a straight wooden plank on the bearing with the dust cover installed.
5. Strike the wooden plank with a hammer until the bearing is fully seated.
6. Check that the bearing and dust cover are fully parallel and level.
7. Make sure the dust cover is level with the top of the eccentric.

Caution

The bearing must sit fully and evenly in the cap. If the bearing is tilted, not fully seated, or not level with the dust cover, do not continue with reassembly.

Step 6: Reassemble the eccentric bottom bracket

1. Place the inner plastic tube into the drive-side cap.
2. Insert the drive-side cap with the tube first.
3. Insert the non-drive-side cap.
4. Reinstall the 3 bolts.
5. Turn the caps until the marks made before disassembly match again.
6. Tighten the 3 bolts with a 4 mm Allen key to a maximum torque of 5 Nm.

Step 7: Reinstall the crank

1. Insert the non-drive-side crank arm with the axle back into the bottom bracket.
2. Make sure the spring wave washer is placed on the non-drive side.
3. Place the spacer onto the axle from the drive side.
4. Reinstall the drive-side crank arm.
5. Tighten the drive-side inner bolt with a 10 mm Allen key to a maximum torque of 54 Nm.

Caution

Do not exceed the specified torque values. Incorrect crank installation can damage the drivetrain and make the bike unsafe to ride.

Step 8: Reinstall the rear wheel

1. Place the rear wheel into the frame.
2. Put the belt onto the front and rear sprockets.
3. Place the axle into the dropout.
4. Check that the belt is seated correctly on both sprockets.
5. Tighten the axle bolts with a 15 mm wrench.

Step 9: Reconnect and adjust the shifter cable

1. Insert the cable hook into the shifter unit.
2. Turn the shifter unit clockwise.
3. Insert the cable adjustment bolt back into place.
4. Shift down to the middle gear shown on the shifter display:

• 4 for 8-speed models
• 5 for 11-speed models

5. Check that the yellow shifter unit markers line up in this gear.
6. If the yellow markers do not line up, move the shifter unit anticlockwise to tighten the cable and let the cable hook settle into place.
7. If the markers still do not line up, adjust the cable with the fine-adjustment bolt on the shifter.

Final safety check

Before riding, check all of the following:

• The eccentric bottom bracket caps are aligned with the original marks.
• The eccentric bottom bracket bolts are tightened to maximum 5 Nm.
• The drive-side crank bolt is tightened to maximum 54 Nm.
• The rear wheel is fully seated in the dropouts.
• The belt sits correctly on both sprockets.
• The shifter cable is connected correctly.
• The yellow shifter markers line up in the middle gear.
• The crank rotates smoothly without grinding, wobble, or side play.
• The bike shifts correctly while stationary and during a careful test ride.

Caution

Do not ride the bike if the crank has play, the belt is not seated correctly, the rear wheel is not secure, or the bike does not shift correctly.

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