I messed up. I wanted to switch out the bottom bracket on my bike. When I tried to do that the toothed cup on the left side (non-chain side) sheared off. The entire thing is now plain with its housing.

edit says: The other side is also not removable as the teeth got - for lack of a better word - destroyed when I tried to unscrew it. Didn't even apply that much force.

Is there a way to remove it without damaging the frame of the bike?

For reference: The 'destroyed' toothed cup you can see in this picture is what I'm talking about. In my case the cup is made out of plastic (I guess, based upon the fact that before it tore off some teeth got shredded).

Bottom bracket with toothed rim

This is the other side where the cup has been sheared off: Other side

edit says: By the way, this is the tool I have been using in combination with a socket wrench: SuperB TB-1065


Sorry it took so long but the bottom bracket is finally out. The cup that had the destroyed teeth was easily removed by combining a spanner and a wrench with the tool. tool combination

The other side - the one with the sheared off bit - was more stubborn and in the end a heat gun, a screw driver and a hammer were necessary to get it out. It was done by heating the cup up without damaging the frame or the bowden cable guard and then hammering the screwdriver into the inside of the cup in a way that unscrewed the cup. The thread of the frame into which the cup was screwed got damaged slightly.

Since Nathan's answer got the first cup out, I'm going to mark his as my answer.

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  • Are you stuck with the entire cartridge in the frame, or just the one sheared off plastic retaining cup? Oct 15, 2018 at 13:26
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    Since it is plastic, the very careful (!) use of a Dremel might help. Careful as not to damage the threads in the frame.
    – Carel
    Oct 15, 2018 at 17:42
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    Is the bottom bracket cartridge dead? Two holes drilled into the plastic and then a pin spanner might get it off, but those plastic bits should not be reused. If you haven't bought a replacement BB, look for one with aluminium threadded bits on both ends ideally, but just one end is workable.
    – Criggie
    Oct 15, 2018 at 23:54
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    @Criggie didn't turn the wrong way, you can see on the 'shredded' part that it came off a bit but it was just too tight for the plastic stuff to handle the stress. And on the side that 'came off' I didn't even apply that much pressure. To me it looked like it was just glued on and the glue didn't hold. "Is the bottom bracket cartridge dead" - if by that you mean if it is damaged then yes. And yeah, next one will definetly have those parts made out of metal. Oct 16, 2018 at 7:10

2 Answers 2


From the look of it, the drive side teeth may yet offer some hope.

The first thing I would do is get some penetrating oil in the threads to maximize your chances of being successful before the teeth get destroyed completely. Apply it around the outside and see if you can get it to weep in, and you can use your BB cable guide's mounting screw hole to apply it from the inside. I use Finish Line Chill Zone and I'm very liberal with it and I recommend this approach as the cold shocking and thermal contraction/expansion seems to do a lot to break up corrosion and get oil worked in. Let it soak 24 hours and then clean and de-grease the outside where the tool will be engaging.

It's not clear whether you're dealing with corrosion here. If you're confident you're not you can skip that step, but it does look to me like the drive side teeth are offering you one more go, whereas doing this once all the teeth are completely gone is one of the more truly difficult things I've come across working on bikes, so making the most of any remaining attempts would be wise.

You need to rig up a way of holding the tool on to the splines tightly. If the spindle is hollow, you can use a quick-release skewer for this, and potentially some washers depending on what kind of tool you're using. Otherwise get a suitably long M8x1 bolt and some washers. Get the tool as lodged into the splines as you can. Tap it in with a hammer or use the quick-release/bolt setup. Then use a long adjustable wrench on the tools's wrench flats. Make sure you're going the right direction, clockwise to loosen the drive side for most bikes.

If that doesn't work, you're probably looking at needing to smash or ram the cartridge through the plastic cups or something similar.

  • sorry but what is 'QR' in this context? Oct 16, 2018 at 7:17
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    @SteffenWinkler "QR" is quick-release skewer for front or rear wheel axles. In this context, it can be used to hold tools tightly pressed to the bottom bracket so that the tool won't jump out of the teeth stripping them. This "hack" can be used, however, if your bottom bracket's axle has a hole from left side to right side, that is, if you can see light through it when look straight into it. Oct 16, 2018 at 9:09
  • Thank you @GrigoryRechistov. Also: just checked and the spindle is not hollow (can't see through. About 1/4th in there is a dead end on both sides) Oct 16, 2018 at 17:54
  • hey, sorry it took so long but a heat gun was necessary in the end and I didn't feel like buying one, so had to wait until I was at my parents during christmas ;). See update at the bottom of my question. Thanks and hope you had a nice christmas! Dec 27, 2018 at 15:48

Assuming the plastic cups are frozen in place in the BB shell, and application of penetrating oil or heat to the shell now is not going to help as there is not a way to grip the cups and un-thread them. You need some way to remove the plastic cup material, or enough of it to be able to force the BB cartridge out.

One way might be to drill a sequence of holes through the plastic cup between the BB shell and cartridge body. The drill would need to be smaller in diameter than the thickness of the cup. You want to avoid damage to the BB shell threads so the holes should be up against the cartridge body.

You would probably need to carefully cut or chisel out the remains of the notched flange to see the plastic material between the BB shell and cartridge body.

enter image description here

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    Rather than try and chisel (and damage the BB shell threads) you could use the drilled holes as entry points to gain leverage to try unthread plastic cups. Needle nose pliers could work, but something like the SPA-1 Pin Spanner would work better.
    – Rider_X
    Oct 15, 2018 at 23:42
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    I would be tempted to drill holes for a pin spanner, then clamp it onto the shell using washers / spacers maybe the right sized socket with an M8 bolt into the spindle. With the pin spanner held in place you may be able to us some percussion to get the shell moving.
    – mattnz
    Oct 16, 2018 at 3:54
  • just for confirmation - as I'm unsure about the vocabulary here - 'BB Shell' refers to the metal part of the bike's frame where the bottom bracket is in, right? From your edits to my question the plastic cub is what I previously described as 'plastic toothed rim' - so I would drill right into those 'teeths'? Oct 16, 2018 at 7:22
  • @SteffenWinkler correct. You want to be careful though, the plastic between the shell and cartridge is likely thinner than the flange with the teeth on it. Oct 16, 2018 at 12:05
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    I like mattnz's suggestion of using a couple of holes for a pin spanner. If it doesn't work, you've only added a couple of holes and can try other things. Another thought to keep in mind is to be sure which way you need to turn the cup for removal. It runs in my mind that the cup on the left side is left-threaded, but it's been so long since I removed one that I'm not sure. You don't want to accidentally tighten it.
    – ichabod
    Oct 16, 2018 at 17:08

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