Saturday, February 16, 2019

Removing An Extremely Stuck Bottom Bracket

I recently picked up an old bike frame for a future project. It's a mid-'70s Motobecane and it seemed to be in decent shape overall, but it did have a drive-side bottom bracket cup that was extremely stuck. The guy I got it from had tried and failed to remove it, so he just sold it to me "as is," bottom bracket bits and all. Being that I couldn't say for certain that the included spindle would work with whatever crank I'd eventually want to use, and the fact that I can never just "leave well-enough alone" I decided I'd need to make sure I could actually remove the stuck cup before I started putting any more money into the project.

I expect that (at least in part) the problem may have been that someone (whether it was the seller I got it from, or perhaps whoever he might have gotten it from) wasn't aware that the bottom bracket was Swiss-threaded and therefore "reverse" or "left-hand" threaded on the drive side. I can picture someone putting arm-breaking effort in the wrong direction trying to remove it, and only making it impossibly tight as a result.

I tried some penetrating oil and letting that soak in for a while, but still couldn't budge it. I tried heating the shell with a heat gun - hoping it might cause it to expand a little - and tried chilling the cup with an ice cube, but none of that helped either.

One thing that makes it difficult to remove a stuck cup is that the outer part of the cup, and the spanner that removes it, are only about ⅛ of an inch thick. Even when the cup is not stuck, it can be difficult to apply the necessary torque without having the wrench slip off. In this case, where the cup was truly seized up, it was near impossible. The wrench would end up slipping, and I was concerned that if that kept happening, eventually the flats on the cup would get rounded off, and then there'd be no getting it off no matter what.

There is a special tool available for removing difficult bottom bracket cups. Here is one from Hozan tools that sells for about $100 or so. There's a similar tool from VAR that costs even more but works in similar fashion. The tool has a notched face that fits over the outside flats of the cup, then has another part that threads on through the bottom bracket shell and tightens up against the inside of the cup, thereby holding the tool securely against the cup and keeping it aligned. I'd love to have one, but for a home mechanic, it's a lot of money considering the limited use it would get.
For my own use at home, I came up with a pretty nifty solution that only cost about 50 cents.

Here it is - a 7/16-inch bolt (about 1-½-in. long, though 1-in. would have worked fine) and a couple of washers. The extra large diameter fender washer was already in my toolbox. One of the other washers was an old crank bolt washer that happened to be just the right inside diameter to fit around the bolt, and just small enough in its outside diameter to fit inside the BB cup without contacting the bearing surfaces, thereby saving the races from damage.
Because there are currently some options available for replacement Swiss-threaded bottom brackets, it wouldn't have been a terrible tragedy if the cup or its races got damaged during removal - but if I could remove it without damage, that would be a plus.

So, here's how it works. The bolt with the smaller washer goes inside the bottom bracket shell, through the bottom bracket cup, with the bolt head and small washer centered in the cup. On the outside, I put on the spanner, sandwiching it in place with the large fender washer and the nut. Tighten it all down.

With the spanner held securely in place over the cup, snugged up to the edge of the bottom bracket shell, I could apply some serious torque, involving a big piece of pipe slipped over the end of the spanner to really extend the leverage. It still took a lot of effort, but I got the thing to move.

There's the cup - with nice undamaged races.
I haven't attempted to use this little hack with an adjustable BB cup, which is the one that typically requires a pin spanner for removal. I imagine it could still work with some small modifications to account for the pins - though those adjustable cups don't seem to get stuck quite as often as the drive-side fixed cups do.

I hope this little home mechanic hack proves helpful to someone out there.


  1. Good solution to the problem. Another way to do this is to use a big bolt and some washers and just keep tightening the nut on the inside with a socket and breaker bar until the cup spins. Saint Sheldon Brown has a good explanation of this on his website. Glad to see a new post from you.

  2. Good to see a post again! That’s a nice tip to keep the tool firmly on the flats of the cup. I do something similar with freewheel removal tools: use the quick release to hold the tool firmly in the freewheel. Once you have movement, the QR can be loosened or removed. It’s particularly helpful with the old two-prong Suntour units!

    For fixed cups I too prefer the bolt tool suggested by Saint Seldon:
    I used it to successfully remove a stuck, 40 year old French-threaded cup from my father’s Gitane. I felt much better about applying leverage to the handle of a socket wrench rather than a BB wrench - the surfaces of the bolt/tool are just so much bigger than the tiny flats of the BB cup.

    I worried about messing up the bearing race so I bought a brass washer in case it came in contact, but it never does anyway. Plus, Sheldon is right, the surface of the BB cup is much harder than soft brass.

  3. For extremely stuck brackets bolting the removal tool in is the only way to go. Especially for Campy brackets, I believe they used aluminum for the cup which is why my tool kept shearing the splines off until I bolted it down. For even more extreme situations, a friend of mine made a similar tool with longer wrench flats that allows two wrenches to be used at once. It took that tool, along with a friend and I both using 2-foot wrenches pulling at the same time to remove a ungreased, seized, crossthreaded BB from a 90s Bridgestone that I had bought. Tapped the shell, good as new.

  4. There's a nuclear option if the wrench flats on the cup are rounded and you can't keep the spanner from slipping. Use your Dremel tool and a thin wafer cutting disc to make a couple of 1/8" x 1/2" long slots on each side of the spindle opening. Then tap a piece of steel bar stock that's 1/8" x 1 1/8' into the keyway you've created and put the biggest Crescent wrench you've got on the barstock close to the cup and wrench away. It will ruin the cup but save the threads in bottom shell. It helps to stuff a wet rag or paper towel into the empty bottom shell to catch the highly abrasive dust and filings the process creates.

  5. I had a very similar experience with a used bike. It had a stuck Shimano BB, the type with a splined hollow spindle. The BB removal tool is also splined, and just as you experienced, it would slip out before I could get enough torque to loosen it. So I thought of the way we use a QR skewer to hold a freewheel tool in place, and proceeded accordingly. I was aided by the presence of the spindle, unlike your situation. I used the crank-fixing bolt from the BB and a big washer to secure it in place against the removal tool. There was still a little play, so I slid a bit of paper clip in there to take up the space. This worked quite nicely, and I was very pleased when my wife said I'd MacGyvered it.

    It's clear from the previous responses that great minds think alike!

    Jon B

  6. I've tried a few methods for removing stuck fixed cups. The best and easiest is simple. Carefully insert the flats of the cup into the jaws of a vise, to prevent marring of the frame, then using the great leverage of the frame to unscrew it. I have removed a few very stuck cups this way.

    1. Hi,I m trying to remove a stubborn BB, tried the vice trick and vice sheared, so pretty tight BB. Still trying to remove it

  7. Now you know why they're called "fixed" cups!

    Seriously, it's a great hack. You probably won't have to use it on the adjustable cup because it's almost always the fixed cup that gets stuck.

  8. older english 3-speed frame, rusty to the max... enough left-hand cup was sticking out that i could get on to it with an 18" pipe wrench. bracing the frame for violent exertion, i reefed on it and it gave up. after a couple of turns i noticed i was unscrewing the right-hand cup at the same time! the axle was so frozen to the cup that it turned the cup all by itself!

  9. I may have been lucky, but a proper fixed cup spanner and a mallet have always worked for me. I've not had to deal with an alloy cup corroded into a steel frame, though; that might require caustic soda.

  10. The Sheldon Brown tool works. Sometimes it takes tremendous force. I had to use a cheater bar to get the thing to grip the stuck cup. But it worked.