Probably's been asked before, but here it goes: I'm attempting to replace the bearings in Rotor Bsa30 cups, the kind that screw into a classic threaded BB. The inside of the bearing is almost flush with the inside of the cup, so there's virtually no lip on the bearing to push, press or tap. Is there an appropriate technique or tool I can use (besides the 200$ Enduro one)?

Phil once made a tool for working on Shimano external cup BB bearings. Don't know if it would also work on yours. Most people will either just pull the bearing cartridge seals, flush and clean the old and add new grease. This can be done with the BB still installed. Or most people will replace the entire BB with new. VERY few try to replace just the bearing and retain the "cup". Andy

Isn't this like $20-30 for the whole assembly? I changed it on my bike last year since I noticed a slight 'something' when moving, spinning cranks by hand when chain was removed. Otherwise I wouldn't even notice the slight drag.

I checked into the cost and just got a new one. If it was expensive, I'd leave it because it was probably nothing to worry about. This looks pretty bad bearing race and if it was just time to spend on removing it and you got plenty of it, I'd say go for it. But it looks like removing it won't be cheap if it can be done at all, the race is probably pressed in and never was meant to be replaceable. And if you remove it, where will you get a new one... I rest the case.

Two of these cost over 50€. It's not about the money per se but why would these precision made alloy cups be disposable? They could last a lifetime. The bearing itself is the disposable item, readily available etc. Anyway, when I installed them I assumed that they would be as easy to replace as BB30's (have the appropriate Park Tool that doesn't fit), but now I see that is not even possible. Relubing is an option but for a long tour I like to prepare the bike with all new cables, housing, bearings etc.

I certainly agree with your standards and goals, but the industry acts otherwise and does what is in their own best interest. Andy

If you had a welder, you could try placing about three equally spaced raised welds onto the inner race. Then maybe use those to drift against.

Or try drilling about three equally spaced holes in the inner race, then maybe you will have some purchase for a thin drift / pin punch. You might find the race is hard to drill, depending on the tools and expertise you have.

Or you could remove the bearing seals, and take your time slowly destroying the bearing inner race and cage. I would say by grinding ( e.g. with a Dremel or preferably a larger tool with a little more grunt ) and then levering out the remnants, and eventually removing the balls. Then you are left with the outer race firmly still held in. With a grinder again ( and using e.g. a "mounted point" in the same grinding tool as before ), you can carefully grind through the outer race at one point, avoiding touching the alloy cups as much as possible, going all across the race. I finish with a small cold chisel to break the race all the way through. Then the interference fit will be lost and you can remove the race. Lots of careful work involved but I have done this type of thing several times, when I didn't have the expensive tool and had the time and inclination to do it.

Keep in mind that BSA30 is a minor miracle that they can make the threaded part thin enough to get a 30mm axle through. This was a later design, not something intended to work in the first place. So that bearing and the tube are as close in size as possible.

I would try a round punch with a sharp edge, working around the circumference of the bearing. But you stand a good chance of knocking the inner race out in the process.

the reason that the entire assy. gets replaced is because trying to remove the bearings will, usually, ruin the cups, and pressing in the new bearings will, most likely, not go well, and requires an exact fit bearing installer tool.... the cups are thin wall aluminum... just supporting the cup without damaging the threads is a challenge for most folks..

ok, so you figure you can do the task, and, by a twist of luck, you get the bearings into the cups... guess what? the cup has been stretched and worn by the replace and the bearings are now too loose in those thin cups.... not a good thing.

the consensus, after a few lengthy discussions online, and not just here on BikeFo, is... get the new assembly.

there are replacements available for between $20 and $110 on Ebay... the expensive one is an Omni Titanium beauty with Ceramic bearings.. new, direct from Omni.
most are in the 30 to $50 range.
new bearings alone cost about $20 to $30...

A slide hammer type blind bearing puller would probably work, but the wall thickness of the threaded portion is so thin, I would be concerned about putting the required impact force on it while threaded into the frame.

umm.. here's a quote from the top post...
"The inside of the bearing is almost flush with the inside of the cup, so there's virtually no lip on the bearing to push, press or tap."
the image posted verifies this.
an expanding plug type puller might work, put you still end up with a loose bearing in an aluminum cup, after finding an exact fit bearing installation driver.

Are you feeling lucky? AND ready to buy expensive tools?


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Be advised that the bearings are bonded into the cups with something like Loctite gap filler, and new ones are unlikely to simply press into place. The cups are just not that valuable.

If the idea of throwing those cups out is infuriating, consider this:


100% disposable. Cups, body, spindle; all of it.

All good points of course, though the Loctite comes as a surprise to me (I had 2 loose bearings in my spares/toolkit on my last tour, thinking I could somehow 'drop them in' if needed). I'm going to the LBS later today and buy some new bearing assemblies, do the inevitable. I did order a Wheels Mfr extractor last week and when that comes in I'll give replacing a try anyway, see how that goes.

Didn't want to try a punch, eh?

Way too little punching finesse...