Press fit bottom bracket standard has become increasingly popular in the cycling world, thanks to its larger spindle diameter, increased stiffness, and reduced weight compared to traditional threaded bottom brackets. However, just like any other bottom brackets over time, push fit bottom brackets can wear out or develop issues, requiring replacement.
This can be a daunting task, as it requires a specific set of tools and careful attention to detail to ensure proper fit and function. In this article, we will discuss what a press fit bottom bracket is, why it was introduced, the different standards, how you can find a correct replacement, and how you can remove and install it correctly using our step-by-step instructions. Whether you’re a seasoned mechanic or new to the world of bicycle maintenance, this guide will provide you with the knowledge and skills necessary to successfully replace a press fit bottom bracket and get back to enjoying your ride.
Tools required
- 8 millimetre or 10 millimetre allen key. One of these tools is used to remove a self-extracting crank arm.
- Mallet. Helps to remove the axle from the bottom bracket.
- Press fit bottom bracket removal tool. Make sure that you have the correct one for your bottom bracket.
To find out which one you need first remove the left-hand crank arm or the crank on the drive side (depending on the type of crankset). If you’re not sure how they come off, you will find help in our article on removing crank arms.
Remove any washers noting the order.
Now measure the diameter of the axle. For 22-24 millimetre axles use the 22-24 millimetre press fit removal tool.
If the axle diameter is about 30 millimeters and the bearings are pressed directly into the frame then the easiest way to remove them is to use the BB30 bottom bracket puller.
If however, the bearings sit in the cups then use the headset and bottom bracket cup removal tool. This is because some press fit bottom bracket cups have narrow sleeves and the bb30 puller doesn’t have enough space to fit in them.
- Bottom bracket press with compatible bushings.
- Grease or anti-seize.
- Isopropyl alcohol.
- Cloth or paper towel.
Removing press fit bottom bracket and finding the correct replacement
To find the correct replacement we advise removing the crankset and the bottom bracket. This way you will be able to get the most accurate measurements.
- First, put the bike in the stand or turn it upside down.
- If you have a front derailleur then shift the chain onto the lowest gear at the front.
- Remove the chain from the chainring.
- Depending on the type of crankset remove the left-hand crank arm or the crank on the drive side.
- Remove any washers noting the order.
- tap the axle with a mallet until it moves.
- Remove the other crank arm by sliding the axle out of the bottom bracket.
- Fit the required bottom bracket removal tool on one side and push the bottom bracket bearing or the cup out of the frame. Do this slowly and check if the bearings coming out to avoid damaging the frame.
- Now repeat the process on the other side.
- Use a vernier caliper to measure the inside diameter of the bottom bracket shell.
- Now measure the width of the bottom bracket shell.
- Finally, measure the crank spindle diameter on both ends where the bearings sit. This is important as some press fit bottom brackets have different bearing sizes on each side.
- Use these measurements to find out which bottom bracket you need
Installing press fit bottom bracket
- Clean the bottom bracket shell with isopropyl alcohol.
- Add some grease or anti-seize to the edges of the shell.
- For the press fit bottom bracket unit check which cup is left and which is right and fit them in the bottom bracket shell.
- Place the correct size bushings on the bearings and slide the bottom bracket bearing press.
- Now, slide the bushing on the other side and fit the handle.
- If you are fitting direct fit bottom bracket bearings then first slide the bushing on one side of the bearing press and slide the bearing so that it sits on the bushing.
- Slide the bearing press through the bottom bracket shell.
- Now place the second bearing on the other bushing and slide them onto the bottom bracket bearing press.
- Fit the handle and screw it clockwise until both sides of the tool touch the bushings.
- Turn the handles until the bearings or the bearing cups are fully pressed in the shell.
- Remove the tool and the bushings.
- Slide the axle and refit the spacers.
- Refit the other crank arm and place the chain back on the chainring.
Conclusion
Replacing a press fit bottom bracket can be intimidating, but with the right tools and techniques, it’s a manageable task. It’s essential to choose the correct replacement for your bike’s specific bottom bracket standard and to follow the proper procedures for removing and installing the new bottom bracket. With a little patience and attention to detail, you can successfully replace your press fit bottom bracket and keep your bike running smoothly for years to come.
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