...bump.

Octalink is the Shimano name for their splined spindle design. Isis is the name for an alternative spline pattern developed by Chris King, Race Face, FSA and others. Square Taper is the traditional style of bottom bracket still used by campagnolo. I know Record10ti will jump in but it is an outdated design. I believe the Velonews quote was" hey Campy, the 70's called and they want their bottom bracket technology back" With FSA cranks you can buy any style. Shiman is only available in Octolink. Since your bike came with Ultegra cranks you already have an Octolink BB. Just order the FSA cranks or Shimano in octolink style. The only exceptin is the new D/A 10 speed crank which takes its own BB. If you decide that you need a new bottom bracket, your bike is English thread and get the narrowest one you can. I believe 108/109.5 is the number. 68x109.5 is what you are looking for

for a guy who sells wheels, that was pretty good:) thanks, Paul!

Hey madisonbucky,

This is a fine question and demanded some investigation. I made a few phone calls, looked up a few things and spoke with our local authority- SuperDave Koesel of Felt Bicycles.

So......

As you know and Paul pointed out, Octalink is Shimano's trademarked bottom bracket spline pattern. It features 8 splines and is Shimano proprietary. In other words, only Shimano cranks or those manufactered under Shimano license can employ the Octalink pattern spline.

ISIS is another pattern which features 10 splines and was introduced as an attempt by independant, non-Shimano component manufacturers to create an alternate industry standard.

In general, there are a greater selection of cranks from a wider variety of manufacturers in the ISIS pattern since manufacturers are not tied to Shimano and their manufacturing licenses.

While the technical merits of each can be argued ad nauseum, the two are roughly comparable mechanically. The greater versatility of ISIS provides some degree of appeal, to include the introduction of certain frames with integrated bottom brackets using greatly oversized bottom brackets and bearings but a spindle with the ISIS pattern, not unlike Cannondale's excellent Hollogram design which is Cannondale's own proprietary pattern. (confused yet?)

Also, in general, Octalink BB spindles measure 109.5 mm wide while most ISIS are 108 mm wide. This usually does not affect fit or "Q" factor from our experience.

Square spindles are still an excellent design employing a much narrower spindle in favour of larger diameter ball bearing on non-sealed cartridge units. The majority of elite track sprinters continue to use square taper bottom bracket spindles due to the ability to run 1/4" ball bearing in their bottom brackets. They believe the benefit is lower bearing resistance and greater durability as well as a high degree of maintainability (but a high need for maintenance also). I use a square bottom bracket in my road bike and prefer it. It seems easier to get a crank squarely mounted with a square taper than with a splined design, with less chance of damage on installation.

Your bike uses an English thread BB shell that is 68 mm wide. Always check your crank manufacturer's recommendation for spindle width. Accept their recommendation. Also, be mindful of torque specs when installing cranks and be certain to check the torque of your chainring bolts, especially a few weeks after initial installation.

I hope that covers it- thanks for a good question!

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Tom Demerly
The Tri Shop.com

Thanks Tom...

only thing, I'm slightly confused...I need a 68mm x 109mm?.....Paul and your message seemed to both say something about size, but I wasn't exactly sure what that was....:)

I found a great deal on DA cranks (9sp) and will probably get the DA BB with it...just making sure I order the right one.

Again, I appreciate the help...

Hey madisonbucky,

You're on the right track. If you buy the English thread BB and the crank together you will be good. Be sure to get the appropriate crank length (that is a whole other topic...) and that your BB is English thread, 68mm wide and you will be fine I bet.

Good luck! let us know the results.

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Tom Demerly
The Tri Shop.com

Get the FSA crank and their high end bottom bracket and forget it.

Yes, you could go with Octalink pattern, but Why? I would just do a wholesale upgrade.

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Call me Big Dick

This spline business makes it easier for manufacturers to make a straight BB spindle that will get a crank mounted on squarely.

Campy probably keeps it that way for one reason: technological and manufacturing superiority. A square spindle is a LOT harder to make correctly than a splined one. Then you have the bearing issue.

You had forgotten one thing about the spindle tapers- there is a JIS taper, and a Campy taper. Yes, there IS a difference.

I will continue to be in the group that runs a square spindle until nobody makes them any more. But I have a feeling that the square spindle WILL soldier on. The boutique are still going to make a square spindle crank because discriminating riders like them and realise the advantages.

My two favorite JIS-taper BBs- the American Classic, and White Industries ti.

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Call me Big Dick

"A square spindle is a LOT harder to make correctly than a splined one."

How so? It seems to me that it would be a lot easier to forge a square spindle than a splined one.

"Then you have the bearing issue. "

What issue is that? ISIS bottom brackets use smaller bearings that may theoretically wear out faster, but Shimano Octalink has no bearing problems.

To the original poster, my recommendation would be to stick with what you've got. If you must upgrade, get the 9s Dura-Ace crank and keep your current bottom bracket. The Ultegra is a bit heavier than the DA but is a sealed unit and doesn't need any servicing. It also isn't as prone to the dreaded creak.

Actually, I would agree that john makes a good point here-

We've had a lot less bottom bracket problems since sealed cartridge bearing bottom brackets and splined spindles came along. I'm not certain why- specifically what is the reason- but it seems we don;t deal with "creaks" and other issues nearly as much. As mechanics, our hands are always clean now too. That's nice.

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Tom Demerly
The Tri Shop.com