What's wrong with Isis bottom brackets?

[ishaw]

I have a couple of nice cranks that are Isis. Middleburn and race face turbines.

If like to use them, but I don't know much about this standard, being used to square taper, octalink and various external standards.

They seem much like the octalink BB, albeit with different spline pattern that interfaces with the cranks. I've no clue as to the merits of this style over octalink, I've only really got experience with m952 BBS, which seem to be fairly robust, at least I've never had issues with the interface (though I have bought dodgy xtr crank arms where I assume ham fisted fitting or loose fitting have resulted in crank wear. Why did road and xtr have v1 spline and others V2?). How does the Isis sine compare?

One thing I have read seems to be the bearings, and the fact that they don't seem to last very long. Why would this be? It all seems quite similar to octalink, and for they matter square taper i.e. captive sealed bearings in the shell mated the the axle, so why are Isis prone to such short lifespans?

As I'd like to use the cranks, I'd like to understand the standard and ultimately source a couple of decent ones for use. Are there any considered better than others? Why? Is powerspline the same as Isis?

Stepping into an unknown and hoping the wise RB sages can help me understand the standard so I can get some cranks fitted. I'd like to run the turbines on mt GT lightning, they are lovely and red.

 

[KermitGKona88]

I have a couple of nice cranks that are Isis. Middleburn and race face turbines.

If like to use them, but I don't know much about this standard, being used to square taper, octalink and various external standards.

They seem much like the octalink BB, albeit with different spline pattern that interfaces with the cranks. I've no clue as to the merits of this style over octalink, I've only really got experience with m952 BBS, which seem to be fairly robust, at least I've never had issues with the interface (though I have bought dodgy xtr crank arms where I assume ham fisted fitting or loose fitting have resulted in crank wear. Why did road and xtr have v1 spline and others V2?). How does the Isis sine compare?

One thing I have read seems to be the bearings, and the fact that they don't seem to last very long. Why would this be? It all seems quite similar to octalink, and for they matter square taper i.e. captive sealed bearings in the shell mated the the axle, so why are Isis prone to such short lifespans?

As I'd like to use the cranks, I'd like to understand the standard and ultimately source a couple of decent ones for use. Are there any considered better than others? Why? Is powerspline the same as Isis?

Stepping into an unknown and hoping the wise RB sages can help me understand the standard so I can get some cranks fitted. I'd like to run the turbines on mt GT lightning, they are lovely and red.

I believe it has to do with the size of the bearings, having an oversized axle compared to square tapered, the bearings are smaller in diameter so wear faster they tried solving it with multiple bearings on Isis, while Shimano moved to HT2 with the cups mounted outside the bottom bracket so they could fit the larger bearings again. That has brought it's own problems with axle length and torsional loads. Octalink V1 caused problems with the axle having short splines and the cranks not gripping enough so degradation of the splines occured, hence V2 with deeper splines.

 

[Tootyred]

Octalink v1 was a disaster waiting to happen....engineering team who thought that was a good idea should have been fired on the spot.

 

[benjabbi]

Octalink seemed to be a stopgap while Shimano waited for the Bullseye crank patent to expire, then came HT2 which is still with us today in basically the same form 20 years later.
International Spline Interface Standard was everyone elses take on the same thing (avoiding the inevitable Shimano patents) and as said the bearings were so small they didn't last.
I had premature wear problems with Raceface and FSA BBs, the best I found were SKF but they were rare and expensive bitd, let alone now.
I jumped ship to HT2 as soon as M960 arrived and these days it's either square taper on retro or HT2 on modern for me.
I'd just avoid anything budget for an ISIS BB, get the best you can find/afford and don't ride it much!
Edit: Powerspline is not the same thing, cheap Truvativ crap that is best avoided like the plague!

 

[madjh]

Square was good, octalink add nothing but were killed by the much better Hollow tech that still are the best choice. Even press fit was a bad idea, lot of noises etc etc.

I only had a RF Issis cranset, the Evolve, and was fine. Avoid V1 as they have told you, go for the V2 . But for me it is a system to avoid. Not many options today and if you have a pre 1997 retro bicycle, it is much better square. I will go even today in a modern bike with the White Industries ENO square, very nice quality and good looking crank set. Square is not dead.

 

[FluffyChicken]

Spline is a spline. They work fine.
ISIS was "invented" by RaceFace and used as an open standard by everyone that wanted too.

To be able to use the larger axle, the bearing size had to shrink as the shell is no larger.
Not always a problem as anyone that has used Mavic headsets will tell you.

Just compare the size of bearings in a sealed Shimano UN to an M950 BB

They also use cartridge bearings, easy to replace, which is needed, but takes up even more room for the races when they can't use the shell/cups and axle itself.

Often used as double row cartridges or mixed with angled or needle bearings.

Unlike headsets, on MTBs they tend to get quite a hammering and I guess smaller contact point, hammering in lots of places against a bearing race constantly gives up at some point.



The basic design doesn't change.
I also found they tend to to deteriorate if used a bit in wet conditions and then they go a bit solid over winter when left.
No idea why, happened on a few different high end makes.
That's recent use (past ten years).

They do make a nicer setup than square, but be prepared to replace bearings. Not all are as easy as others and they cost as much as a BB themselves.

 

[joglo]

It wasn't just RaceFace but also ChrisKing and Truvative, starting ISIS and as mentioned on the link from @benjabbi introducing this to the world at the Interbike show 1999


I do have one crank with ISIS and never had issues, but to me also something I'm rather avoiding, simply because it never reached a huge success.
Square bottom bracket rules for us here at least in pre 97 area, others using HT2 with external cubs.

 

[FluffyChicken]

Yeah, I couldn't be bothered to type Truvativ etc...
It's all here on the spec documents
https://www.isisdrive.com/

 

[kaydee]

they don’t last,simple.As Kermit said,they oversized the axle but shrank the bearing balls,it was good as aconcept but they never lasted long .
My wifes Merlin got through 4 of them in 2 years and my cheap shimano square drive UN52 which was fitted at the same time as her first isis lasted 8 years.
A good friend of mine owns a bike dealership and he hated them.
Save yourself the grief bud ,don’t bother .
By the way my wifes cranks were also race face in gunmetal are were really nice cranks,but I sold them on and fitted her bike with a square drive and middleburns.That set up is still running smooth after 7 ish years.
All the best

 

[Shenlong]

SKF or Trialtech. Better designs than other brands