Not one of the easiest jobs and fortunately not a job that has to done too regularly, but sometimes you have to replace those bottom bracket bearings. On a general strip and cleanup of my Poggio this weekend I took my chainset off as I suspected my bearings might need attention.
The are lots of standards for bottom brackets, frames and chainsets; some are interchangeable and others are not. The removal method is dependent on the type, so it’s important to make sure you know what you are dealing with.
My Poggio is the 2103 version and it’s the P1.5 model. If yours is the same then you should be dealing with the same components. If you have another model or year then things might be a little different. Hopefully this post will still be interesting and provide an insight even so.
The 2013 Poggio frameset is the same for all models and so the one thing that’s consistent for sure is that the frame has a BB86 shell. The shell is the part of the frame where the bearing cups are mounted into and in turn, the bearing cups have the bearings mounted into them. Usually you replace the the bearings and cups together as one piece, unless you have a more expensive bottom bracket like one of the Hope ones. The BB86 standard defines an 86.5 mm width, a 41 mm diameter and is push fit. The photo below shows the frame with the bearing/cup removed and you can see the aluminium surface where the bearing cup sits once pushed in.
So, how to remove the chainset. The GXP system incorporates a non-drive side crank that has a self-extracting bolt, this is what holds the whole chainset together. If you look at the non-drive side crank you will see two hex bolts; a smaller one inside (and behind) another larger one. When you undo the smaller one it pushes against the larger one (which should remain fixed and not rotate) and the crank arm should ease away from the spindle. If the larger one rotates then you have a problem. When you’ve wound out the nut far enough the whole crank arm should come away in your hand and the self-extracting nut will remain in place. For my chainset the bolt is an 8 mm hex, this should be the same for yours but on a different model it may be different. Note this will be very tight; it is a standard thread so undo it in the usual anti-clockwise rotation.
A quick tap on the exposed end of the spindle with a rubber mallet should now see it pushed through and out the other side of the frame. Release the chain from the chainring and you can put the whole chainset to one side and concentrate on removing the bottom bracket cups.
There are tools for removing the cups. Buy and use one of these if you want to. On the other hand I found that a suitable sized piece of wood dowel and a hammer did the job just fine. Generally the better your tools the quicker and easier the job and the less care you need to take, but often you can still get the job done without the pro kit. What you need to do no matter what tools you have is apply enough force to the back of the cup to pop it out of the frame.
I used wood because it ‘gives’ and therefore softens the blow. The end of my wood dowel did deform in places which is exactly what you’d expect and the bearing cups came out just fine. Because the dowel was smaller than the ID of the bearing cup I did have to tap the cup several times and work my way around the different sides in order to push it free but a little time and perseverance go a long way.
So that’s the cups/bearings out and I was indeed correct, one of them had seized. The non-drive side wouldn’t turn at all. As for fitting new ones; I’m still waiting for them to be delivered so that will have to be the content of another post.