Question about 73mm bottom bracket shells

[Ray Varella]

If I have a crank that requires a 122mm spindle with a +5mm offset on a 68mm bottom bracket shell,

Will a 127mm +5mm offset work with a 68mm cartridge bottom bracket with something like Phil Wood mounting rings?

Is that clear?

Thank you 

Ray

[Benz Ouyang, Sunnyvale, CA]

You shouldn't change the spindle length because the spindle length is primarily used to determine chainline.

What you should do is to look for a BB spindle length 122mm, but with a 2.5mm offset*. Then you can use a lipless mounting ring to secure the shorter cartridge BB in the wider BB shell. Not all Shimano left side mounting rings have lips; some are lipless like the Phil Wood, so don't feel like you need to spend as much on a mounting ring as on the entire cartridge BB.

BTW, you may or may not run into clearance issues with the crank butting up against the BB shell (left) and/or Cartridge BB (right), and you may or may not run into the BB shell running out of threads on the left side.

Good luck!

* Assuming 5mm offset is to the right, so (73-68)/2 should be deducted to give the same chainline.

[Ray Varella]

Thank you Benz, that clarifies things. 

It’s an academic question as I don’t have a bike with a 73mm shell. 

I own plenty of parts to keep a few bikes on the road for the foreseeable future. 

I can’t really justify adding a new standard with plenty of good stuff on hand. 

Cheers,

Ray

[Gustavo Vasquez]

Ray, 

I had a similar issue that was resolved going to a 127mm spindle. It offset it enough. 

I do not think you’d need get a 73mm shell with a spacer. (Which I’ve never tried) 

I did this on a vintage Ed Litton mountain bike with a asymmetrical 122 (121.5?) spindle and a triple crankset. 

Sent from my iPhone

On Feb 7, 2021, at 1:47 PM, Ray Varella <rayvar...@gmail.com> wrote:

If I have a crank that requires a 122mm spindle with a +5mm offset on a 68mm bottom bracket shell,

--
You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group.
To unsubscribe from this group and stop receiving emails from it, send an email to rbw-owners-bun...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/rbw-owners-bunch/25dc404c-40c3-4c0e-b4b2-fbe936bf60e3n%40googlegroups.com.