Octalink Cartridge Bb Fitting Problem

[Soop Dogg]

Ok, so I was servicing my hybrid and felt a little bit of play in the bottom bracket. It's been in there for about 25,000km, so time for a change.

Unfortunately it's a Shimano Octalink BB, and as I don't want to change the chainset, I pulled the old one to get the numbers off it and order one the same.

In the end, it turned out to be an ES21, 68mm shell and 121mm spindle length. I ordered an ES51 of exactly the same dimensions but apparently it's slightly better quality. (although why I would want it to be any better than the old one as it lasted so long is beyond me now!)

Anyway, i cleaned up all of the threads and installed the cartridge from the drive side first - all good. Then I wound the cup in on the non-drive side. As I tightened it up, I noticed that the spindle was getting tighter in the cartridge. When the cup is properly tight in the BB shell, the spindle is really tight. As I back it off about a turn and a half, it frees up again.

Any idea why this might happen in a sealed cartridge unit? Is there a shim that I could get to put between the shell and the cup? I really haven't come across this before, and I've changed enough bottom brackets in my time. (I go back to about 35 years ago working on my bikes, right up to external BB's on my carbon road bikes & MTB's nowadays)

Thanks in advance for any advice you might come up with!

 

[alfeng]

Ok, so I was servicing my hybrid and felt a little bit of play in the bottom bracket. It's been in there for about 25,000km, so time for a change.

Unfortunately it's a Shimano Octalink BB, and as I don't want to change the chainset, I pulled the old one to get the numbers off it and order one the same.

In the end, it turned out to be an ES21, 68mm shell and 121mm spindle length. I ordered an ES51 of exactly the same dimensions but apparently it's slightly better quality. (although why I would want it to be any better than the old one as it lasted so long is beyond me now!)

Anyway, i cleaned up all of the threads and installed the cartridge from the drive side first - all good. Then I wound the cup in on the non-drive side. As I tightened it up, I noticed that the spindle was getting tighter in the cartridge. When the cup is properly tight in the BB shell, the spindle is really tight. As I back it off about a turn and a half, it frees up again.

Any idea why this might happen in a sealed cartridge unit? Is there a shim that I could get to put between the shell and the cup? I really haven't come across this before, and I've changed enough bottom brackets in my time. (I go back to about 35 years ago working on my bikes, right up to external BB's on my carbon road bikes & MTB's nowadays)

Thanks in advance for any advice you might come up with!

FWIW. I cannot tell you WHY you experienced what occurred ...

However, I have experienced what I will consider to be a comparable situation with more than one Octalink BB cartridge (after all these years, I still love the Octalink BB interface, BTW) ...

In my case, I found it was all but impossible to thread the non-driveside cup completely into the BB shell.

Presuming that you indeed have a BB which is designed to fit a 68mm shell and not a 73mm shell, the rather simple solution which worked for me was to thread the non-drivedside cup in FIRST ...

The inside of the cup should be lightly greased, of course ...

And then, thread the driveside cup-and-cartridge into the BB shell.

Reversing the 'logical' order of assembly makes the task almost effortless, IMO.

I can only guess as to why reversing the assembly order works ...

But, why speculate-on-or-question what works!?!

Again, THAT is what I found worked for me ... and so, there are NO PROMISES that it will work for you.

 

[oldbobcat]

Any idea why this might happen in a sealed cartridge unit? Is there a shim that I could get to put between the shell and the cup? I really haven't come across this before, and I've changed enough bottom brackets in my time. (I go back to about 35 years ago working on my bikes, right up to external BB's on my carbon road bikes & MTB's nowadays)

I've seen this, too, and I have no idea why. A 1mm Shimano 10sp cassette shim on the left usually lets you properly tighten the lock ring without changing the chainline, though.

 

[Soop Dogg]

Thanks for the replies.

I'll try the method of tightening up the non-drive side first and see how that goes. Like you say, it does sound weird, but why question what works? If that doesn't work, I'll try spacing it with a cassette shim.

Thanks again for taking the time to help me out.