Cassette biting into aluminium freehub body

[almostvegancyclist]

Hi all,

I got a new rear wheel with an aluminium freehub body (Mavic Allroad S), switching from Shimano with a steel freehub body. As I was tightening the cassette lockring, it felt a bit "mushy" like when you are stripping threads off. So I stopped the process, took the cassette off to see what was up and it looks like the smallest cog has dug into the tips of the freehub body splines, like in the photo (this isn't mine but it shows the same damage). Apparently this is "normal" for aluminium freehubs? Is that true? Should I not worry about this? The cassette is on and seems to be working fine.

 

[midlandsgrimpeur]

Yes, it is completely normal and alu freehubs are more prone as the metal is softer. Basically as you pedal the cassette cogs dig into the splines and score the freehub body. Won't affect the cassette or freehub and highly unlikely to cause any damage other than a bit of superficial marking.

 

[si_c]

As above, to be expected on any aluminium freehub body.

More of an issue for larger riders as more force is put through the cassette and it can sometimes cause sticking when putting the cassette back on. But by the time it becomes an insurmountable issue then it'll likely be time to replace the body anyway.

 

[Yellow Saddle]

Whilst it may be a frequent occurrance, it is not normal i.e. desirable. Under certain circumstances you sometimes can't even get the rings off unless you rotate them counterclockwise with a chainwip to get them out of the groove. Freehub bodies made from aluminium are an artifact of a 1980s design that didn't foresee the weight weenie phenomena.

Anyway, file off the little bulges before fitting a new cassette. The good news is that aluminium work hardens and the rate of damage will decrease quite dramatically from now on.

 

[almostvegancyclist]

Thanks!

 

[almostvegancyclist]

I've asked Mavic the same question and had this interesting reply:

"The phenomenon that you can observe on the grooves of the free hub does not in any way alter the proper functioning of the free hub and only the disassembly of the cassette can be difficult. Moreover, it is advisable to mount monobloc cassettes and to avoid the use of single sprockets in order to reduce these marks or erosions on the free hub."

But most quality cassettes come with separable cogs?

 

[roubaixtuesday]

That's nowt lad. Here's what a touring tandem can do to that soft aluminium.

https://www.cyclechat.net/threads/what-have-you-fettled-today.87079/page-1081#post-7266188

(Subsequently replaced with a steel one)

 

[ColinJ]

Moreover, it is advisable to mount monobloc cassettes and to avoid the use of single sprockets in order to reduce these marks or erosions on the free hub

That's nowt lad. Here's what a touring tandem can do to that soft aluminium.

This is what @colly did to his freehub splines on one forum ride!

'Titan legs' @colly managed to rip a sprocket through his Mavic splines on one ride...

View attachment 615516

He was just ahead of me as we came to a short, steep ramp, changed to an easy climbing gear, and suddenly found his legs spinning like crazy and his bike coming to a halt!

 

[Marchrider]

are you tightening the locknut up to the recommended torque ? often 40/45nm which is very tight. if you just tighten them without a torque wrench you may not be getting them any way near tight enough

 

[roubaixtuesday]

are you tightening the locknut up to the recommended torque ? often 40/45nm which is very tight. if you just tighten them without a torque wrench you may not be getting them any way near tight enough

Why would that make a difference? Surely the splines take the load, regardless of locknut torque?

 

[roubaixtuesday]

This is what @colly did to his freehub splines on one forum ride!



He was just ahead of me as we came to a short, steep ramp, changed to an easy climbing gear, and suddenly found his legs spinning like crazy and his bike coming to a halt!

Wow. That freehub looks weird, with just thin ridges to take the load.

 

[Marchrider]

Why would that make a difference? Surely the splines take the load, regardless of locknut torque?

I imagine that when not fully tight the sprocket you are driving will be delivering most of the energy to the freehub, when fully tight that energy is shared by the rest of the cassette.

I noticed this primarily because I disassemble my cassettes so as to reverse worn sprockets. and without those rivets holding it together the mess of the freehub is notable - fully tightening it to 45nm stops this.
although the rivets holding the casstte together seem tight, I imaging there will still be movement

 

[ColinJ]

Wow. That freehub looks weird, with just thin ridges to take the load.

Yes, it was a pretty poor design, and his cassette was individual sprockets so the pedalling forces were more focused.

 

[roubaixtuesday]

I imagine that when not fully tight the sprocket you are driving will be delivering most of the energy to the freehub, when fully tight that energy is shared by the rest of the cassette.

I noticed this primarily because I disassemble my cassettes so as to reverse worn sprockets. and without those rivets holding it together the mess of the freehub is notable - fully tightening it to 45nm stops this.
although the rivets holding the casstte together seem tight, I imaging there will still be movement

Fair enough.

IIRC only the smallest two sprockets are free on a 9 speed, the rest riveted. I'd be amazed if the friction from torquing down the locknut is more effective at that than the rivets though.

 

[ColinJ]

I noticed this primarily because I disassemble my cassettes so as to reverse worn sprockets

That's an interesting idea, but I definitely can't do that with my Campagnolo cassettes because the spline pattern is not symmetrical.

I have an old rear wheel with a Shimano freehub, and some Shimano sprockets. I will check them... Hmm, same problem - the sprockets only seem to go on one way round!