Replacing a Shimano Press-Fit, or BB86, bottom bracket.

There are a ridiculous number of competing bottom bracket standards in the bike world at the moment but I eventually established that mine (on a 2015 Giant Defy Advanced 2) was what is called a BB86 bottom bracket. The bottom bracket shell is 86.5 mm wide, 41 mm in internal diameter and accepts a 24 mm axle. The increasingly creaky nature of mine, and the fact that it has 2506.6 miles on it, led me to decide to replace it.

I ordered the bottom bracket and a Park Tool BB86 bottom bracket removal tool from Wiggle, made a red-neck bearing installer and got to work. It was very easy job, I could probably do the whole job again in five minutes, involving some basic tools and a smear of grease.

Firstly, to make the installation tool you'll need to visit B&Q and pick up a length of M12 threaded rod, a pack of M12 nuts and a pack of heavy duty square washers.

You need to saw off approximately seven inches of the threaded rod and smooth the cut end with a file. At one end, using plenty of thread locker, jam two of the nuts together to form a solid fixed end. Now add a square washer and one of the two dies that come with the Park Tool remover. Do the same at the other end but use one nut and leave it free so you can tighten it when you're pressing the new cups into the bottom bracket shell.The materials for this cost less than £9 and because there were four square washers in the pack I was able to make a second tool for my mate Phil at work. If you bought two packs of square washers, you could make four tools for about £11 - red-necking it for the win!

Secondly, here's a quick look at the grease I use on bikes. It's Finish Line grease with teflon. I've used it since it first appeared in the very early nineties when it came in a black tube with white writing. I've seen loose ball bottom brackets packed with this stuff looking absolutely perfect after a couple of brutal Scottish winters of mountain biking abuse.

If anything, I think it's actually improved since then, it used to be white and slightly translucent looking but now it's a sort of cream colour and smoother and stickier.

Anyhow, here's how it's done:

1. Loosen the two 5 mm bolts that hold the crank to the axle and use a Hollowtech II tool to unscrew the plastic adjustment plug from the axle.

2. Here's a pic with it removed. It's a good idea to smear some grease on the internal threads in the end of the axle when you're re-assembling later.

3. Now finish loosening off the two 5 mm allen bolts and, making sure you lift the retaining tab in the gap between the bolts, wiggle the crank off the axle.

4. You now need to unhook the chain from the chainring and carefully let it rest on the BB shell. You can now grab the driveside crank and pull the whole assembly out of the bottom bracket. You may need to bang the exposed end of the axle with the heel of your hand to get it moving.

5. You now need to insert the narrow end of the removal tool though one side of the bottom bracket and pull it until you hear the splayed end of the tool click into place behind the bottom bracket cup.

6. Using a fairly heavy metal hammer, hit the solid end of the tool sharply to get the cup moving and then a few more times to remove it. Mine wasn't difficult, it took three moderate blows and the cup popped out. Remove the central sleeve and remove the other cup. I found I had to insert the tool from the other side, narrow end first again, because the splayed end wouldn't seat behind the remaining cup easily from the now open side.

7. It surprised me how much muck and soil was in the bottom bracket shell. Needless to say, remove as much of it as you can now

8. Get the area as clean as you can and smear a good layer of grease around the inside of where the new bearing cup is going to seat in the shell.

9. With the seating area clean and greased, mount the new bearings either side of the shell (not forgetting to slot the central sleeve into one of the cups) and then assemble the red-neck bearing press through the whole assembly. Do the free nut up finger tight keeping everything as lined up as you can and then start turning the nut with an 19 mm spanner. I was expecting potential trouble at this point but the cups pressed in beautifully, one side seated first and when it was seated the other side followed it in. Tighten until you're sure both cups are flush with the frame but don't go mad; this is a bike, not a cylinder head.

10. And there you have it, job done - a nice new bottom bracket fitted. Re-assembly is easy, just put everything back in the order you removed it.

When you're re-attaching the non-drive side crank, you snug the crank onto the axle using the black screw in plug. Do it barely hand tight, just until you're the crank is seated but the whole crank assembly still spins freely. Now tighten the two 5 mm bolts, alternating between the two until they're both nice and snug.

Update since buying a torque wrench: The suggested value for these bolts is 12-14 nm. Tighten them alternately but bare in mind that once both bolts are at the correct torque value, the one you tightened first will have loosened slightly so tighten each bolt to the chosen value at least twice.