Shimano press fit BB removal … again.

Following on from this thread ……
http://singletrackworld.com/forum/topic/shimano-press-fit-bb-diy-removalrefitting

I’ve been thinking about this and was wondering how you actually get to the back of the bottom bracket cup to fit a tool to bash it out.

Isn’t there a plastic tube that connects to both bb cups that the axle runs through.

If so how do you get to the back of the cup or am I missing something simple.

Cheers

Steve

The tube will have a wider internal diameter than the cup so there’s an “edge” for the tool to press against.

I’m not sure to be honest.

If you look at the picture of the bottom bracket in the link in my first post it looks like the tube goes into the hole of the cup.

The business end of the tool compresses to pass through the bearing and then springs out just behind the cup, where there’s a gap of larger diameter before the tube starts. Bit difficult to describe in words, but more obvious when you look at it and the tool…

The tube will have a wider internal diameter than the cup so there’s an “edge” for the tool to press against.

this, and there are 3 notches in the rear face of the bearing that you can use as a guide for your drift (I don’t know if that’s what they’re there for)

Ok cheers.

I will have a proper look when my dropper turns up.

I’m hoping I can get away with removing only one cup and the tube so I can run the cable for the post.

You should be able to though it’s possible the central tube will be stuck there if you don’t remove both. That said, it’s so easy to remove them, I can’t see that being a real problem.

The tube will have a wider internal diameter than the cup so there’s an “edge” for the tool to press against.

this, and there are 3 notches in the rear face of the bearing that you can use as a guide for your drift (I don’t know if that’s what they’re there for)

Actually no – its the other way around, the cup is a larger diameter than the tube. The key is that there is a gap between the bearing and tube which allows the sprung tool to expand and grip the rear of the cup.

The bearing is 24mm diameter, the tube 26mm, and the cup 31mm. The difference of a few mm between the bearing & tube is not enough to get a decent grip, and by bashing on the bearing anyway, you’re likely to knock it out and leave the outer cup in place (this is why so many people destroy the bearing trying to get it out!) The proper tool will pass through the bearing and expand into the 5mm or so gap between the bearing and tube, and allow you to push on the back of the cup.

If you don’t have the tool and use a screwdriver instead, you insert the screwdriver at an angle to get it into this gap.

and there are 3 notches in the rear face of the bearing that you can use as a guide for your drift (I don’t know if that’s what they’re there for

Not on any Shimano ones I’ve used (BB51, BB71, BB91, BB94)??

My cups were so stuck I had to melt them out with a heat gun

Did they squeak? Silver linings and all that 🙂

@perthmtb

Ah, thanks for that. It makes sense that the tube is wider than the bearing though I didn’t know how much. It must press in to a further inboard than the bearing.

did you buy the Giant dropper or another brand ?

I’ve bought a giAnt one as got a good deal on a brand new one.

nice one, post up how you find it in practise please

Will do although I may wait until the end of the month before fitting so I can get a new bb just in case I balls this one up taking it out.

Is it worth upgrading to a hope or something.

Iainc – my boys have giant dropper posts. Both are pretty good. Almost as good as the reverbs but with less maintenance. Good budget option tbh.

^^ thanks for that. Have a reverb on the Soul which is almost 2 yrs old (well not really as it was warrantied last summer) and just bought an Anthem SX with the Giant dropper, but not ridden it yet..

I used a slidehammer bearing puller to remove the BB92 from my Trance. The tool was actually pulling against the bearing and not the plastic cup. Fortunately the bearing was such a tight fit it stayed in place and pulled the whole cup out with it.

Just make sure you get the right sized one. 😉

Serious answer.
If you’re carefull you can remove either cup on a pressfit BB with a hammer and punch/ screwdriver then press it back in with some threaded bar and washers or hammer.
It takes very little force to push them in or out.

@renton

Belive it or not, I managed to fit the giant dropper on to my Trance without removing the BB.

The only tool I used was a vaccum cleaner… thread some dental floss down the seat tube, and using the vac hose, suck the floss down the seat tube and then up the downtube, and out through where the cables exit. It worked first time for me!

I then attached some gear cable to the floss and pulled that back through, then thread the outer hose back over the cable. I also used a knife to make the hole in the rubber gromit wider, to accomadate the additional cable.

@Klaus.

That sounds ace. Will certainly give that a go first then.