Diary of a Mountain Biker

Date: 7th to 9th August 2008

The bearings on my Shimano XT Hollowtech II bottom bracket have felt worn for a while and I finally bit the bullet and ordered some more from Enduro Fork Seals plus a 50% stake in one of their beautifully machined 'outboard' bearing bottom bracket - bearing press (Huey is purchasing the other 50%).

Here's an indication of how I used the bearing puller. This is just an indication of how I did the job. Please read the disclaimer and for full instructions refer to the Enduro Fork Seals site.

Extracting the old bearings

Pushing in the new bearings

Extracting the old bearings

Step 1
Purchase or borrow an 'outboard' bearing bottom bracket - bearing press and a new set of bearings

Step 2
Remove the bearing cups from your bike. Two particularly grim looking specimen's below

Step 3
Put one of the bearing cups down on a flat surface with the wider end/bearings at the bottom i.e. touching the flat surface and put the 'collet' inside the bearing cup with the champfered edge at the top. Don't be surprised that the collet does not touch the sides of the bearing cup, that will happen on the next step

Step 4
Push the 'collet expander' (the piece that looks like a large bullet) inside the collet. This will have the effect of pushing the collet apart to grip onto the bearings

Step 5
Pick up the bearing cup together with the collet and collet expander and push the bearing cup into the bearing cup holder

Step 6
Insert the bolt into the collet expander and using an 8mm allen wrench turn clockwise until you feel the bearing pop out.

Step 7
You know have two bearing free bottom bracket cups. Clean them thoroughly before moving onto the next stage i.e. pushing in the new bearings.

Pushing in the new bearings

Step 1
Gather the necessary parts together, bearing cup and new bearings plus the outboard bearing bottom bracket - bearing press

Step 2
Place the 'bearing guide' into the cup holder. Note this is two sided and you need to have the side facing upwards that fits your bearings

Step 3
This is easily checked by putting the bearings onto the bearing guide.

Step 4
Put the bearing cup over the new bearings. It will help to grease the insude of the cup before doing this.

Step 5
Put the 'support' on top of the bearing cup. Note that the champfered edge should be face down and will sit inside the bearing cup

Step 6
Insert the bolt through the top of the 'support' and using an 8mm allen wrench turn clockwise to push the bearing cup onto the new bearings. Note how the bearing cup sinks from about 4mm above the cup holder in the second picture to almost level to the top of the cup holder in the third picture.

Step 7
Remove the bolt and you have a perfectly fitted bearing. Repeat for the second cup

Step 8
Insert the bottom bracket back onto the bike and don't forget to cover the bearing surface with the larger of the two sets of orange seals that are provided.