Stompier
Senior Member
Track chainline is typically 42mm, so 57mm is a long way off. HT2 BBs will not be adjustable, but then neither will most of the other sealed units BBs (like 7710) either.
Fixed gear / drivetrain wear distribution
- Thread starter silva
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Track chainline is typically 42mm, so 57mm is a long way off. HT2 BBs will not be adjustable, but then neither will most of the other sealed units BBs (like 7710) either.
Nevertheless octalink apparently was possible - only that unlike my previous bike where I can see the side of the axle and thus the splined shape, I can't see it with this bike from the outside. My previous bike showed external cilindric ends too, this bike not, everything sits inside the bottom bracket shell.
How would an axle be 'adjustable'?
In order to make a chainline straight, an axle length is chosen.
Is octalink / hollowtech different than square taper in this?
Stompier
Senior Member
Axles are not generally adjustable laterally. You seemed to be implying that they were. To be honest, I'm not really sure what your issue actually is.
I might be misunderstanding, but if you put spacers on Hollowtech BB on the drive side you can move the chain ring to change the chainline ?
Stompier
Senior Member
In principle you could do that. But you would also limit the amount of axle showing on the NDS and the crank arm might not seat properly or tighten effectively.
davidphilips
Phil Pip
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If you did this you would also move the crank arms both over to the right, you may not notice it when cycling but the bike would be better if you did not.
I didn't mean adjustable, also not implying in any way (that I can think of). In a square taper case, one choses a longer axle in order to change the distance from chainring to center (aka chainline). According to the dealer, in the case HollowTech, there is only one axle length, so nothing else to chose and thus no chainline change possible.
Stompier
Senior Member
The dealer is correct.
So the answer on my question
"In order to make a chainline straight, an axle length is chosen.
Is octalink / hollowtech different than square taper in this?"
was a yes on hollowtech.
Hollowtech is a derival of octalink.
Apparently octalink on its own does allow axle length choice.
What is the reason for the hollowtech system only allowing one axle length?
Stompier
Senior Member
Just to be clear - are you talking about hollowtech, or hollowtech 2? They are very different. Hollowtech 1 is basically Octalink in design. Hollowtech 2 has external screw in cups. It is not possible to alter chainline on Hollowtech 2. The only way to alter chainline on Hollowtech 1/Octalink is by switching axle length. But I don't know enough about HT1 to know if different axle lengths are available. And even if they are/were, the system has been out of production for so long that they might not be that easy to find anyway.
Generally speaking - if you're running single speed, it's going to be so much easier to use square taper bb/chainset, especially if you're using track ends and a fixed/ss rear wheel. If you're running some kind of hybrid/road conversion, then I can't really help.
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Stompier
Senior Member
Octalink was certainly available in different sizes, but I think you're barking up the wrong tree by looking for a solution to all this by pursuing an outdated technical standard which is long past its sell-by date (by about 10 years at least).
I actually wanted hollowtech as attempt to solve a couple problems, for a simple reason: my previous bike had such a bottom bracket / axle and unlike the last bike with its square taper axle it didn't suffer a chain tension variation nor broken cranks.
Hollowtech proved itself for me, and know what, over the years/decades I noticed that old things lasted longer than new ones.
