Shimano 6700 cassette damaged Zipp freehub

[rliu]

Hi I was running 6700 cassette on Zipp 30s and today tried to change over to 6800 cassettes (the hub is a 11 speed one but I was using a spacer to run the 10 speed 6700). When I took the cassette off I noticed that some of the middle sprockets had cut into the freehub splines and made little 'chew dents'. I was planning to just file these down and put the 6800 cassettes on. I just wondered if anyone else has come across this and whether just filing it is a good idea? A theory of mine is that the hub is designed for 11 speeds and didn't agree as well with a 10 speed cassette so hopefully the 6800 won't damage the hub all over again.

 

[Citius]

File the burrs down and move on. Just about every ally freehub will do that, regardless of how many speeds...

 

[Smokin Joe]

File the burrs down and move on. Just about every ally freehub will do that, regardless of how many speeds...

Yep, a common occurrence.

 

[accountantpete]

It's down to the lightweight material and I think the 6700 only has the biggest three sprockets joined on a common rail (the larger individual sprockets tend to eat into softer materials hence the design). The 6800 also has the next pair similarly joined so you should be ok as is.

 

[Smurfy]

When I took the cassette off I noticed that some of the middle sprockets had cut into the freehub splines and made little 'chew dents'.

You need to keep the cassette lockring at the prescribed torque. If you fail to do that, the sprockets may move independently of each other (depending on cassette design). In that case all the pedalling load can then end up going into just a small section of the freehub splines that is just one sprocket wide, rather than being distributed across all the sprockets in the cassette and the full width of the freehub splines. Your observation that not all the sprockets have bitten into the freehub body suggests that this may have happened in your case. Lockring torque setting is usually stamped on the lockring periphery, my Shimano one says 40 Nm.

 

[Yellow Saddle]

You need to keep the cassette lockring at the prescribed torque. If you fail to do that, the sprockets may move independently of each other (depending on cassette design). In that case all the pedalling load can then end up going into just a small section of the freehub splines that is just one sprocket wide, rather than being distributed across all the sprockets in the cassette and the full width of the freehub splines. Your observation that not all the sprockets have bitten into the freehub body suggests that this may have happened in your case. Lockring torque setting is usually stamped on the lockring periphery, my Shimano one says 40 Nm.

No amount of lockring torque will remedy the problem. You cannot eliminate rotational movement of the sprocket by the axial force a lockring provides. The problem is a direct result of the weight-weenie phenomena. The constant quest for shaving weight of components and Shimano's myopic design saw to it that a freehub body that was designed as a steel component, has been made lighter by using aluminium instead. Campagnolo either saw the problem at the design stage or got lucky and designed its splines differently.

The good news is that aluminium work-hardens and that the sprockets will bite into the freehub body only up to a point, thereafter the metal's hardness resists further damage in all but the strongest/heaviest users' bikes.

@OP, file the burr away so that you can fit and remove the cassette.

 

[Smurfy]

The good news is that aluminium work-hardens and that the sprockets will bite into the freehub body only up to a point, thereafter the metal's hardness resists further damage in all but the strongest/heaviest users' bikes.

If I recall correctly @ColinJ may have a tale to tell about this.

Ah yes, after some forum dredging, here it is. Note that only one sprocket has ripped through, and the rest of the splines appear to be completely undamaged. And perhaps not surprisingly it is the largest sprocket, as this allows the rider to apply the highest driving torque to the splines. I'd say that strongly suggests the lockring was not tight enough. It is also a campag spline pattern with tall splines, which you say is a superior design in this respect.

Or (much less likely), you've 'done a ("Legs of steel") colly' and ripped a sprocket through the splines!

If I could be bothered, I'd calculate the clamping force produced by the lockring, the resulting friction between the cassette and the freehub body, the torque required to overcome that friction, and the force required at the pedal to cause slippage.

Of course the other factor is that in some cassettes most of the sprockets are rivetted together, which will assist in loading the full width of the spline, regardless of whether the lockring is not tight enough. While on others the entire cassette consists of loose sprockets, which makes the ripping through disaster more likely if the cassette lockring is not tightened to the correct torque.

Oh, and in case you are wondering, colly, the person who suffered the disaster pictured, is quite a slim and light rider.

 

[lpretro1]

It's very common - see it all the time in our workshop and we simply file the burrs off neatly once we've prised the cassette off which can be difficult in worst cases and it is mostly cosmetic. It happens on a wide range of freehub body and cassette combinations (Hope actually make a steel freehub body for their hubs for those who don't want this problem - it is slightly heavier but for your average Joe it won't be noticed). Yes, it helps to buy the better quality cassettes which have the spider carriers

 

[ColinJ]

If I recall correctly @ColinJ may have a tale to tell about this.

[colly's problem]

Oh, and in case you are wondering, colly, the person who suffered the disaster pictured, is quite a slim and light rider.

It was very amusing to see the look on his face when he selected that gear! We had just plunged down a steep hill to a bridge over a river and there was a steep little climb back up from the bridge. Colly selected a big sprocket and his legs span like crazy but created zero drive. He ran out of momentum before the top of the climb. I can't remember if he dismounted or hastily selected a gear that worked.

He discovered the cause of the problem after taking the cassette off when he got home.

I have been extra careful to double-check the tightness of cassette lockrings since then ...

 

[Yellow Saddle]

If I recall correctly @ColinJ may have a tale to tell about this.

Ah yes, after some forum dredging, here it is. Note that only one sprocket has ripped through, and the rest of the splines appear to be completely undamaged. And perhaps not surprisingly it is the largest sprocket, as this allows the rider to apply the highest driving torque to the splines. I'd say that strongly suggests the lockring was not tight enough. It is also a campag spline pattern with tall splines, which you say is a superior design in this respect.

Yes, I did say that Campag has a superior design but not all third-party freehubs follow Campag's pragmatic line. Some create ridiculously small splines or even leave some out, all of which will still work with the Campag cassette. I doubt the freehub in question looks anything like the original Campag design - not in pattern but in depth and contact area.

If I could be bothered, I'd calculate the clamping force produced by the lockring, the resulting friction between the cassette and the freehub body, the torque required to overcome that friction, and the force required at the pedal to cause slippage.

Well, if you can't be bothered to do a simple calculation with readily available data, then don't diss the counter argument. But before you do or don't do the calculation, make sure you understand where the said friction comes from. It does not come from the suggestions you make above.

You could perform a simple experiment.
Find two chainwhips.
Have on hand one wheel with cassette fitted.
Torque the lockring to 50NM or above.
Fit the two chainwhips to adjacent non-grouped sprockets so that the one whip pulls clockwise, the other anti-clockwise.
Apply pressure and note now easy the sprocket makes a small movement to take up the lash from the imperfect spacing between sprocket and freehub body.

Of course the other factor is that in some cassettes most of the sprockets are rivetted together, which will assist in loading the full width of the spline, regardless of whether the lockring is not tight enough. While on others the entire cassette consists of loose sprockets, which makes the ripping through disaster more likely if the cassette lockring is not tightened to the correct torque.

Oh, and in case you are wondering, colly, the person who suffered the disaster pictured, is quite a slim and light rider.

Yes, cheaper cassettes are often riveted together avoid just this problem. More expensive cassettes are riveted onto wide-flange spiders. However, most of them still have a single sprocket or two - usually the smaller ones, but freehub biting is still a problem, even on smaller sprockets.
Stop trying to convince yourself that you will eliminate the problem by upping the lockring torque. You won't.

 

[Citius]

I'd say that strongly suggests the lockring was not tight enough

It doesn't suggest anything of the sort.

 

[Yellow Saddle]

It was very amusing to see the look on his face when he selected that gear! We had just plunged down a steep hill to a bridge over a river and there was a steep little climb back up from the bridge. Colly selected a big sprocket and his legs span like crazy but created zero drive. He ran out of momentum before the top of the climb. I can't remember if he dismounted or hastily selected a gear that worked.

He discovered the cause of the problem after taking the cassette off when he got home.

I have been extra careful to double-check the tightness of cassette lockrings since then ...

If the wheel in question is the Mavic one in the photo and the sprocket broke the splines and rotated freely on the freehub, then the problem was not lockring tightness but French design.

 

[Globalti]

On my Mavic Ksyrium SL wheels the rim and spokes are excellent and the hub and freehub work fine but require regular stripping and maintenance, which not all riders will do. Failure to maintain the freehub leads evetually to the Mavic "howl of death".

 

[Yellow Saddle]

On my Mavic Ksyrium SL wheels the rim and spokes are excellent and the hub and freehub work fine but require regular stripping and maintenance, which not all riders will do. Failure to maintain the freehub leads evetually to the Mavic "howl of death".

Mavic wheels have so many engineering flaws that I often think they were designed by a first-year student in a design school where they're asked to redesign the bicycle wheel. The result of these exercises is always a mess, a bit like one of those Citroens with upholstery padding on the outside of the doors.

The freehub is poor, the spoke design stupid, the rim/spoke interface a joke and the skewer silly. Zee French are only equally in their folly by Ze Swees with their crappy DT Swiss hub, rim, shock and fork designs.

 

[Globalti]

I disagree, the skewers are excellent.

The rims and spokes are super-strong and super-stiff making a nice stiff wheel but yes, they are impossible to adjust or replace.