Trying to remove a bottom bracket, planning on replacing it with a new one as I build up a single speed. Trouble is I can't get the cups off. Wondering if anyone can recommend the proper specialty tool to do so. Or, wondering if maybe these are not threaded but pressed? I just can't tell. It is a 70s or so era Sekine road bike. Image attached. Many thanks in advance.

I believe these are threaded in. You need a tool that engages the internal spline, which I believe is the same as a Shimano cassette tool. Remember that this is likely a BSC/ISO thread, meaning it's right and left threading. If so the right side (as you sit on the bike) has a left hand thread, and the left is right.

Hard to tell from the picture but is that an Ashtabula bb cup?

Using the frame tubes as a frame of reference, it's too small for a standard pressed in Ashtabula cup. Plus there are the splines on the ID. But it is difficult to tell from the picture.

The OP could provide the OD of the bottom bracket shell, then it would be easy to give a definitive answer.

the remote internet guessing with a cell phone picture..
falls short of going to a Bike-shop and just getting it Done.

Typically the cup faces inward and the view would be the one on the far side of the BB shell ..


this a leftover from Warsaw Pact manufacturing in Bulgaria or Yugoslavia ? etc.

not so familiar to me.

It might be a cell phone picture but the camera has more megapixels than most other entry level digital cameras out there. And isn't this forum partly to assist people who would like to do things themselves instead of just "bringing it to a bike shop"?

In any case, appreciate the insights here.

OP and OD?

OP- Original Poster
OD- Outside Diameter

Thanks for that. I never know when it's OK to use shorthand or not.

In any case the photo is OK, except that there's no scale to use as a dimensional reference.

To the original poster, next time put a ruler into the photo so those viewing have a frame of reference. Or you can use a penny or quarter.

But just eyeballing the diameter compared to the frame tubes, I'm still fairly confident that this is a standard ISO threaded BB.

If the cups face outward what does the crank spindle look like ? bound to be a odd one ..

if you need a spline tool to remove it Its none I've ever come across ..

insufficient information offered..

The bike made in Canada , I had see a few in my day , but the BB 's cups can be remove with Parktool's FR-1 , if that doesn't work a pipe wrench on the outer rim of the cups will .

First, your picture is just fine. It's in focus and the depth of field is better than many pictures we see.

Now on to the kudos: Well done! You have offered up a rarity and completely flummoxed the old guys...including me...who have seen just about every thing. I think what you have is a Thompson bottom bracket. You can find some information on them on-line but they are apparently very rare. Here's a bit of a discussion on one. They must be rare if you can leave me, FBinNY, Hillrider and fietsbob saying

I've no idea how you can get the cups out, however. If they are pressed into place, you could drive them out with a drift and a hammer but getting them back in may be difficult. I found a tool on-line to do it but it costs $550. If they are threaded into place, you'd need the specific tool with the proper splines to get a purchase on the part.

Frankly, this is a sleeping dog that you'd be better off just leaving it lie. If it is pressed into place, you are going to have a hard time finding a replacement...they are rare after all. Threaded is easier as long as you can find the proper threading.

Years ago there was a German or Swiss bottom bracket that looked sort of like this. The spindle was threaded to accept the cone much the same way Ashtabula cranks are. I forgot (40+ years) the name, but vaguely remember it starting with an H, or it might have been a Thun, or one of these.

If the OP posts a new picture, he should include the rest of the BB assembly.

More info could determine if the cups are pressed. If there is a reasonable chance they are threaded in, improvising a tool may be your best bet.

This may be a dead-end, but I would try it:

Find a nut that fits just into the splines (there are twelve) and screw it onto a left (reverse) threaded hex bolt with a spacer between the nut and the head of the bolt. Put the bolt through the BB so that the nut sits on the edge of the splines, and the head of the bolt is just outside the cup, where you are able to get a grip on it with a wrench (hence the spacer). A counter-clockwise turn of the bolt should tighten the nut and put counter-clockwise torque on the cup. Perhaps you can try the right cup first with a regular bolt (and a clockwise turn of the bolt), since there is a chance the cup itself will be reverse threaded.

Lots of great info here, thanks. I'm attaching a picture with the rest of it. I am in Canada if that helps solve the riddle. I'll send a few more images at better angles by tomorrow.

Appears as if Its an ISIS Spline to fit the crankarms ,


why not just put fresh balls in the retainers grease it up and purt it back together ?


BMX?

Wow, that is truly a bizarre setup. I've never even heard of anything like this before.

I hope for your sake the shell is standard English threaded. Otherwise you're definitely stuck with the bottom bracket and crank that you have now.

I just may do that. Going to eat my words and bring it into a shop on the weekend and see if they have a tool that will do the trick. If it's going to take some improvisation only to find that it will be a struggle to find a replacement I will definitely just replace the balls and giver.

Just in case it isn't BSC/ISO right/left threads, have the shop remove the left cup first. These are always RH threaded. Then the shop can check the thread, which will dictate which way the right cup comes off.

I know this kit, seen it a couple of times.

Shimano Selecta. Standard BB threads.

https://www.bikeforums.net/showthread...a-square-taper

So, answer the question at issue, threaded or pressed in?

Guess you missed my edit^

Anyway, I solved the puzzle, you can google the rest

...threaded, standard threading. Other thread says one of the older Shimano freewheel tools will fit the splines for removal.

Or you can check my earlier posts, starting with number 2

Um, hit Ctrl-F and type selecta?