Bike Repair – Replace Your BB92 Bottom Bracket

Cyclist replacing BB92 bottom bracket

Here’s how to remove and replace another common press fit bottom bracket type – BB92.

  1. Remove the chain

Give your bike a good clean, then clamp it in a workstand. Use degreaser and a rag to make sure there’s no dirt or grime left on the cranks or in the BB area. Use a pair of Power Link pliers (SRAM) or a chain tool (Shimano) to remove the chain, and place it to one side. If your bike has a chain guide, slide the guides out of the way.

  • Remove cranks – Shimano

If you have Shimano cranks, first loosen both of the 5mm Allen key bolts on the non-driveside crank arm, turning them anticlockwise. Fit the Hollowtech II end cap tool and turn it anticlockwise to remove the end cap. Use a small screwdriver to disengage the security plate between the two clamping faces. The non-driveside crank should now pull off.

2.2 Remove cranks – Other

If you have a Truvativ GXP or SRAM crankset, use an 8mm Allen key to undo the axle bolt in the nondriveside crank arm, turning it anticlockwise until the crank arm comes away from the axle.

  1. Tap out axle

Tap the end of the axle with a plastic or rubber mallet to start it moving. You should now be able to remove the driveside crank arm and axle from the frame. Watch out for any falling spacers and make a note of where they came from and what order they were positioned in.

  1. Clean and degrease

Give the spacers a clean and set them down somewhere in the order they were removed. Give the cranks and the BB area of the frame another really good clean with degreaser and a rag. This is a good chance to give your chainring(s) a clean too.

  1. Compare BBS

With the cranks removed, it’s time to check you’ve got the right BB to replace the worn one with. SRAM cranks need a SRAM GXP BB92 BB and Shimano cranks need a Shimano BB92 BB. If your cranks are from another brand, measure the inside diameter of the worn non-driveside BB cup with a Vernier calliper. If it’s 24mm, a Shimano BB should do the job nicely.

  1. Remove old BB

Insert the press-fit BB tool through the drive side of the BB, non splayed end first. As it slides through, the wings should splay out to sit against the bearing. If possible, get someone to brace the frame. Then, with the tool fully engaged, hit the protruding end carefully with a mallet from the non-drive side until the driveside bearing and cup come out.

  1. Remove old BB

With the driveside cup removed, insert the pressfit BB tool through the non-drive side of the BB and repeat step 6 to remove the non-driveside bearing and cup.

  1. Clean inner shell

If your BB proves particularly stubborn, it’s worth taking the bike to your local bike shop for some expert advice – you don’t want to wreck your frame, after all. With the old BB out of the frame, give the inner shell a good clean with degreaser and a rag. Check for any imperfections or marks on the pressfit surfaces.

  1. Grease inner shell

It’s installation time! To prepare the frame’s BB shell, coat it in a generous helping of anti-seize grease. If you’re installing a GXP BB, you’ll need to make sure you install the BB the right way around. The cups have LH or RH marked on them – RH (Right Hand) being the drive side and LH (Left Hand) being the non-drive side, which has a smaller internal diameter.

  1. Grease BB

Sit one of the bearing press adaptors that comes with the press-fit BB tool against each cup. SRAM cranks will need the adaptor to be fitted backwards on the non-driveside cup so the force is applied across the bearing, not just on the inner race. Coat the BB’s inner axle seal in grease, sit the cups in place on the frame, then slide the headset press through the BB shell.

  1. Press in BB

With the bearing press adaptors correctly orientated and the new BB cups sitting squarely against the frame, slowly turn the handle of the headset press clockwise to press the BB gently into the frame, constantly checking the alignment and that the cups are pressed into the frame as squarely as possible.

  1. Check BB position

When the lips of the BB cup sit against the edge of the BB shell, the installation is complete. Don’t tighten the headset press unnecessarily, because this can damage the bearings. Wipe any grease away to check that the BB is fully pressed into place. Once you’re sure all is good, undo the headset press and pull the tool from the frame.

  1. Refit cranks 1

Now get the BB ready for refitting the cranks. If it’s a SRAM BB, cover the inner seals on both cups with grease before sliding the outer driveside seal on to the crank axle along with any other spacers and the spring washer you may have removed earlier. Cover the axle in a film of grease before pushing the driveside crank/axle assembly through the BB.

  1. Refit cranks 2

If it’s a SRAM BB, fit the non-driveside seal before refitting the non-driveside crank arm. If it’s a SRAM crankset, use a torque wrench to tighten the 8mm Allen key bolt to 50Nm. If it’s a Shimano crankset, slide the non-driveside crank arm into place, reseat the security plate and refit the end cap, only doing it up finger tight. Torque the 5mm bolts to 12-15Nm.

  1. Final checks

Spin the cranks. They should move smoothly and easily, without resistance. Check for any play in the system by holding the frame in one hand, the end of a crank arm in the other and trying to force movement. If all is good, refit the chain using a new Power Link or joining pin, check the gears are properly adjusted and, where relevant, re-adjust the chain guide.

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