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ISIS vs. Octalink? Can someone explain?(12 posts)

ISIS vs. Octalink? Can someone explain?jzinckgra
May 18, 2003 6:33 AM
Hi guys,
Got a quick question regarding BB's and FSA's carbon crankset. I currently have an earlier (5 years old) set of the FSA cranks mounted to a World Class Ti BB. The BB is square tapered and is 103mm in length. I'm thinking of getting a new set of FSA cranks so I can use the old ones to build up another bike. Anyways, I notice there a two options for the cranks: ISIS or Octalink, both of which I don't think will fit my square taper BB. Also, some web sites advertise the cranks as being either 9speed or 10 speed, in addition to being available in the square taper. I currently use campy 9 speed chorus equip., but don't understand why the cranks would be labelled as either 9 or 10 speed. Wouldn't either work with my 9 speed equip? If I wanted to keep my current BB, which FSA cranks should I order? Sorry for the naive q's, but just want to double check before i lay down the cash. thanks
re: ISIS vs. Octalink? Can someone explain?Akirasho
May 18, 2003 7:09 AM
... ISIS was/is a group of components manufacturer's response to the slow speed at which Shimano initially handed out license for their pipe billet Octalink splined bottom bracket spindle... and the two (ISIS and Octalink) are incompatible... likewise, neither is compatible with square tapers...

For a time, FSA was offering different versions (ISIS, Octalink and square taper) on all (I think) of their road cranks... but this no longer seems to be the case. It appears as though the Team Issue is now only available in the splined patterns... but there may be some older tapers still around.

In general, I believe it's the rings... not the cranks that are "rear cog specific" (can someone else confirm this). When Shimano went from 8 to nine, they fidgeted with the front rings to ease shifting over the cog range... I suspect a similar manipulation going to 10 (no biggie).

To use your current BB, it looks like you're looking at the FSA Carbon Pro for a 103mm chainline (see specs on their website)

... In addition, contacting FSA might not be a bad idea too...

12810 NE 178th St. Suite 102

Woodinville, WA 98072

Phone – 425 488 8653

Toll Free – 877 RIDE FSA

Fax – 425 489 1082

e-mail –

Be the bike.
I'd buy ISIS...C-40
May 18, 2003 10:30 AM
The 103mm length Shimano (JIS taper) BB is no longer supported by Shimnao. Shimnao is also in the process of changing their BB spindles to the new XTR style. The new DA 10 speed group is the next to have this BB. The octalink will probably be phased out in a few years.

The "10 speed" cranks have square tapers to fit Campy 102mm BBs. The the angle of Campy's taper is the same as shimano but the size of the taper is not. Don't put a Campy compatible crank on a shimano BB. It won't go all the way onto the spindle and the chainline will be about 5mm too far to the right.

The ISIS spline can be manufactured by anyone, without worry about patent infringement. FSA sells a pretty respectable Ti spindle BB for $85. The 10 speed ISIS crank should work fine with your 9 speed drivetrain.
Yes, but....jzinckgra
May 18, 2003 1:16 PM
...why can't I get an ISIS BB in a 103mm width? FSA only has 108mm as their smallest. I've used a larger BB before and the Q factor was way too much, which is why I eventually went with a 103mm square taper.
Yes, but....russw19
May 18, 2003 5:19 PM
Because the 108 is what is designed to fit their ISIS cranks. You fit a bottom bracket's spindle length to the crank you are mounting to it. So for the FSA ISIS cranks, you use an ISIS 108mm BB.

Also regarding your 9/10 speed crank question. The outer ring on Campy's 10 speed cranks is slightly closer to the inner ring as well as slightly thinner. This is to accomadate the thinner 10 speed chain. It will work fine on a 9 speed drivetrain. Equally, the 9 speed cranks work just fine on the 10 speed drivetrains. I have seen many reports of mixing and matching without problems.

By the way, Q-factor is a function of the cranks, not really the BB spindle. You can look up the Q-factor of the FSA cranks on their website.

I would avoid ISIS...Matno
May 20, 2003 7:44 AM
Check out MTBR for MANY tales of woe regarding ISIS bottom brackets. It seems that the design is inherently flawed in that it doesn't allow room for properly sized bearings. Lots of them (including ones from very reputable manufacturers) are conking out prematurely. Chris King did their own testing and decided they couldn't make an ISIS BB worthy of their reputation. That says a lot in and of itself.

OctaLink is a better design, works flawlessly, and is now available from several manufacturers. (Well, a few at least). I'd stick with what works. Just my $.02...
about chris king...C-40
May 20, 2003 10:49 AM
I see nothing on the King website that supports your statements. The website still says that when King makes a BB it will be an ISIS.

As for the octalink working flawlessly, there are also many reports of problems with the DA BB.

If you read enough, you will won't find a product made that someone has not had a problem with. Personally, I've never had a BB problem in 20 years of riding.
about chris king...russw19
May 20, 2003 12:25 PM
There are two things that the guys at Chris King want to get into, but don't have the time to commit to right now.
One is selling complete built wheels on their hubs, the other is a bottom bracket.

I think Matno, that you are thinking of Phil Wood. They are trying to design an oversized shell BB that uses an ISIS spindle to mate with 9mm diameter bearings. There are two ways they are looking at doing this... one is a bigger bottom bracket shell on the frame (requires a change of standard from frame manufacturers) and the other is to put the bearings outboard of the BB shell (ala Shimano XTR) but they haven't perfected either one yet.

Now, as for the ISIS BB's failing... here's the problem... everyone is aware of the weakest link in the chain theory, right? Well the ISIS spindle is so stiff and strong by it's design, that it doesn't flex. When your cranks flex the spindle actually is deforming the cartridge bearings and that is what is causing them to die. However, those same bearings can be replaced, and cheap. About $15 a set at a bearing shop. I would replace them once a year to be safe anyways.

The alternative is to do what Shimano does.. their spindle is also super stiff, so that is why the Dura-Ace BB uses the needle bearings in the set up. It allows the spindle to move without destroying a round ball bearing. Needle bearings displace the load better.

That is what I have heard from my friends at FSA.. that is what their research is pointing to.. the spindle is so stiff that it is crushing the bearings when loaded because it doesn't flex.

That could be corporate BS said to cover for them not really knowing, but I know the guy who told me that and I tend to believe it.

Scuttlebutt down at the precinct is...Matno
May 20, 2003 2:19 PM
My information came second hand. However, if you waste as much time on online forums as I have, you can tell when a product is disproportionately dissed. Such is the case with the ISIS BB's. Of course, I got my info from MTBR, and road biking may not have the same impact on a BB (although I suspect it does). Lots of people have had problems with them. More than the "average" product by a good margin. FSA's explanation may be true. It's always hard to tell when the source is considerably biased. However, their explanation doesn't sound right at all. Bearings should last LONGER when there is no flex. That's why titanium spindle pedals aren't nearly as durable as steel ones. The flexy titanium wears out the bearings faster. Of course, you reach a point where anything can be "durable enough," assuming you replace gear on a semi-regular basis.

Also, a couple of people on MTBR posted information they got directly from employees at Chris King explaining why they have yet to adopt the ISIS standard. In fact, one guy was told that CK is probably NEVER going to adopt ISIS because of the inherent design weaknesses. The website still sounds optimistic, but their explanation has been the same for a long time. (i.e. the part that lists their excuses for not getting around to it hasn't changed. It's been a long time since they added "that period is over" and we still haven't seen anything).
So if not ISIS. then what?jzinckgra
May 21, 2003 5:34 PM
So if ISIS BB's are prone to premature wear, then who else sells octalink BB's other than Shimano? I can't seem to find any.
So if not ISIS. then what?russw19
May 21, 2003 11:58 PM
Well, I am still not convinced about the ISIS BB having too many problems... I just haven't seen them and I work for a pretty large shop that sells a lot of them....But what Matno says makes sense, I just can't back what he said.

But what you just asked is a different question. ISIS and Octalink are NOT the same thing! The ONLY company that makes Octalink BB's is Shimano. NOBODY else makes them. Just Shimano. Octalink, as the name implies is an 8 spline pattern. ISIS is a 10 spline pattern. And on top of all that, if you need an Octalink BB, the Dura-Ace BB is one of the best BB on the market, period. It's super light, it's sitff and strong, and it's smooth as a baby's butt coated in baby oil. But you have to face your bottom bracket shell before you install one or you run the risk of the needle bearings not lining up and causing premature wear. If properly installed and adjusted, I am conviced they are one of the best BB's sold today. I have one in a Cannondale that has almost 40,000 miles on it in just over 5 years. Still as smooth as the day I installed it.

So if not ISIS. then what?johnmyster
May 22, 2003 7:07 AM
Octalink was Shimano's patented standard. They released it several years ago, and as I was more into mtn biking at the time, I know it showed up first there, on lx and xt level equipment. Even within the shimano mountain groups, there are SEVERAL different octalink setups, all with cranks and BBs that are incompatable with each other. My new hollowtech xt cranks are on the way, and I know that I was required to buy the ES-71 BB, and not the ES-70 that was compatible with the xt octalink cranks of last season.

They have been (up until the release of the NEW 2004 dura-ace) been more forgiving within the road line. I'm pretty sure that the same bottom brackets currently fit current 105, ult., and d/a current cranksets.

So, Shimano hit the mountain scene with the splined setup, which was superior to the taper, and patented the beast. That made Bontrager, RaceFace, FSA, and Truvativ engineers pretty upset. They all came together, and made their OWN setup, calling it ISIS, that anyone (probably anyone other than Shimano) could have free access to. So this is where we are.

My opinions follow: I have a friend with a raceface BB/crank ISIS setup on a beast mountain bike. Hers is great, she loves it. On mtbr, truvativ splined (the one that pricepoint gives package deals on) gets bad reviews, but I would higly reccommend a higher quality (more than $25) raceface products. She also had for many years (still commutes on) a great taper raceface BB before that, great product also.

Awhile back, there was a tech letter into velonews (Zinn?) asking why often D/A equipped bikes (new octalink) are spec.d with Ultegra BBs. His response is the design of the product. The D/A (he said) had better bearings from a performance standpoint (stiffer, less friction, etc.) than the Ultegras. Good for racing: looser seals = lower friction = faster. However, he mentioned that the sealed ball bearing ultegras prooved far more durable in low maintenance situations. So the D/A unit is great if you have a team mechanic, or otherwise pull your BB out every few thousand miles to clean, lube and otherwise pamper the unit. However, the ultegra unit, giving up a bit on performance, would proove more durable to those of us who forget our BBs after riding in the rain and want to do nothing but occasionally snug up our BB shells every 5k miles with a spanner wrench (from the side, you can do this on the new octa-ultegra, as I do) without removal of your cranks. This was what he said, I don't know anyone that has put on substantial mileage on a D/A unit while neglecting it.

What would I do? I'd look for a raceface isis that got good reviews (do they make them that fit road frames?) If so, I'd go that route, it's probably sealed all up and meant to be abused in mud and muck offroad forever. Oherwise, I'd get an ultegra octalink, and maybe even buy a spare one in 2004, incase the ultegra goes to the two piece, external bearing, 10 speed design of the 2004 D/A in 2005. I personally, wouldn't value either setup (ultegra octalink with FSA vs. raceface isis with FSA) as being better or worse. Both great engineering, prooven, and setups that should be available for awhile.

Shop for bottom brackets, find one that fits your frame, and buy your crank, without worrying about it any more.