BB90 with octalink - is this possible?

Discuss light weight issues concerning road bikes & parts.
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se245
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Joined: Fri Mar 29, 2013 4:46 pm

by se245

Hi,

My dad (who lives on the other side of the world) previously passed on to his grateful son (me) a newish Trek Madone. Money is a bit tight for me, so I delayed buying a groupset to build it up. In the end, he has sent me his old groupset as he has upgraded to an electronic version. The crankset is an FSA model with Octalink fittings, though I don't have the spindle. From what I understand, the bottom bracket fitting for the frame is BB90. Is it possible to put these two together? I went to the best bike shop in town to get the crankset fitted but I live in Sweden and I couldn't really understand what the mechanic advised, though it was clear he wasn't sure how to help me. After looking around on the internet I'm starting to wonder if BB90 and Octalink are technologies that don't intermix, though I can't find anything conclusive. The bearing units are still in the frame, though perhaps that's not helpful (?).

I'd be grateful for any advice - bottom brackets have always been a mystery to me. If I can sort out this issue, I can happily build up the rest of the bike myself.

Thanks,
Simon

sigismond0
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Joined: Tue Feb 05, 2013 8:29 pm

by sigismond0

Octalink isn't any different from any other English or Italian threaded bottom bracket, so you'd need a BB90-to-BSA adapter. Unfortunately, BB90 is wider than BSA, so I don't think there's any such thing.

I'm a little confused, however. I was under the impression that Octalink was only used by Shimano on 5500, 6500, and 7400 cranksets, and nobody else was allowed to use their BB standard. FSA helped create the ISIS standard to compete with Shimano's closed Octalink standard. Very few cranksets use either of these anymore.

If your FSA crankset has the spindle attached to the crankarms, then you don't actually have Octalink or ISIS and all you need is this:
http://www.bikepedia.com/PA/Item.aspx?I ... VW-51csCk0

If you do have Octalink or ISIS, you simply won't be able to use the cranks and there's no adapter due to the BB shell of BB90 being wider than an entire BSA bottom bracket.

by Weenie


eric
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by eric

FSA made a ton of ISIS cranks. You can tell between Octalink and ISIS by looking at the splines in the crank- Octalink has 8 partial splines (on the outer side of the crank- the inner side is a round taper fit), ISIS has 10 complete splines. Obviously they do not interchange. I know Ritchey made some Octalink cranks. I think that a lot of people incorrectly call FSA cranks Octalink when they are really ISIS but it's possible that they made some real Octalink cranks.

Both types are just cranks without an integral spindle like most modern cranks have. The spindle is part of the BB.

Both Octalink and ISIS BBs only fit BSA (threaded) frames. You can't fit them in a BB90 frame as sigismond0 points out.

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yourdaguy
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by yourdaguy

FSA made Octalink cranks at one time in certain models. I have 2 tandem cranks on my tandem that are FSA with Shimano Octilink bottom brackets. About the time FSA started making Octalink, Shimano came out with external bottom brackets and pretty much nobody made Octalink cranks after that.
For certain parts stiffer is more important than lighter.

sigismond0
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by sigismond0

As an owner of a 5500 crankset, I can confirm that you should avoid Octalink. Not because there's anything wrong with it, but rather than there are (as far as I can tell) only three Octalink BBs ever made--Shimano 5500, 6500, and 7700. And they're not particularly cheap to replace.

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yourdaguy
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by yourdaguy

They also make various widths in those quality levels so there are actually about 8 models.
For certain parts stiffer is more important than lighter.

sigismond0
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by sigismond0

True, but for any given bike there are only three options. For example, I can only choose among the three standard versions. People with triples can only choose among the three triples, etc. Unfortunately, none have been in production for some time now and even the lower end 105 model is hard to find for less than $50. If you have an Octalink crankset and intend to keep it, I'd suggest picking up a spare BB now rather than waiting five years for your first one to wear out.

There are tons of Octalink 2 BBs floating around, but those are the MTB version, and not too helpful.

se245
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Joined: Fri Mar 29, 2013 4:46 pm

by se245

Thanks for all your helpful responses. Looks like I'll need to source some alternative cranks.

Just to clarify, they are indeed Octalink (V2, I think), rather than ISIS fit. It is true that Shimano developed this technology, but they licensed it out to other manufacturers. A major issue, apparently, was the amount they charged for this privilege and this prompted a few independent companies to band together and develop ISIS. According to what I've read, these issues prompted developments like BB90 to be open to all, because the companies responsible had learned from Shimano's mistakes.

Can any of you tell me whether I can get cranks that would both fit to the existing chainrings and be compatible with the BB90, or am I better off finding a complete chainset?

eric
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by eric

They're a standard bolt pattern- either 130mm or 110mm "compact" bolt circles- so the rings should fit any crank with the same BCD. They may not fit aesthetically however.

Your best deal will probably be medium or low end cranks on sale. A quick search shows Ultegra 6600 cranks on closeout for well under $200, i.e.
http://www.cambriabike.com/Shimano-Ulte ... 39-53T.asp

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yourdaguy
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by yourdaguy

By the time others besides Shimano were making octalink it was octalink II.
For certain parts stiffer is more important than lighter.

by Weenie


thisisatest
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by thisisatest

Other companies made octalink cranks almost from the get-go. Nobody made octalink bottom brackets except for Shimano.
Shimano road cranks and mountain XTR were always octalink v1. Shimano mountain cranks, except for the XTR, were v2. Other companies' road cranks would have followed v1 fitment, their mountain cranks could be either. For instance, Cannondale 2x9 expert cranks were made both ways, with only a small "es" printed on the back of the v2 type denoting its compatibility with ES-70, ES-50, etc...

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