Shimano Octalink BB & cranks

Marky
Marky Posts: 504
edited October 2008 in Workshop
Hi. Has this been discussed before?

Why did Shimano create the two different Octalink types, Road and MTB, so that there then has to be the two different types of bottom bracket? Was it so they could sell more stuff or was there a mechanical beneficial reason?

I’m guessing there’d be no harm having them all interchangeable, just like it was with square taper bottom brackets.

When Campag Ergo shifters of various 8 or 9-speed variations needed to be paired with compatible rear mechs I thought that was really unnecessary and a nuisance for customers. And I thought it was good that Shimano didn’t have that same issue. But with Octalink, apart from needing the correct length, I’m thinking why couldn’t they all fit onto each other?? Nuts.

Does anyone have any ideas about that situation?

Cheers. Mark.

Comments

  • nicklouse
    nicklouse Posts: 50,673
    sorry there are not really two different types. (road and mtb).

    yes there are 2 different spline patterns V1 and V2 but both appearer in both road and and MTB.
    V1 being on the higher level kit.
    "Do not follow where the path may lead, Go instead where there is no path, and Leave a Trail."
    Parktools :?:SheldonBrown
  • aracer
    aracer Posts: 1,649
    It's for exactly the same reason Campag changed their rear mechs with 10-speed (and Shimano changed theirs after the original DA indexed mech - though most don't remember that). It's because an issue was found with the original Octalink BB design - the one used for DA, Ultegra, 105 and XTR. The difference isn't between high and low end kit but between different ages of kit - they decided that the original version wasn't strong enough (at least for MTB use) so came out with the second generation for later MTB use (and finally for lower end road groups). Of course it wasn't then worth changing the existing cranks to be compatible with the new version - which wouldn't in any case solve the problem as there would still be 2 different BBs needed for aftermarket replacement.

    So I'm sorry - the reason is an accident of history rather than anything malicious.