Mick F wrote:Yes, whatever system of sprockets you use shouldn't produce damage like that. I appears that your sprockets aren't a good fit to the splines. I reckon your freehub unit is fit only for scrap.
IMO not scrap just yet, but on the way unless the aluminium indents have work hardened. Re-assemble and check after another 600miles. But if I were ICE I'd be 'concerned'
It took a good deal of strength, chainwhip and locking tool to get it off.
Locking tool was the shortest handle, about 20cm. I don't doubt that it had been tightened to the indicated 40Nm. Don't see that it could have self tightened appreciably.
Bob
40Nm over 20cm is 200N force, or the weight of a 20kg mass.
A shortcut has to be a challenge, otherwise it would just be the way.No situation is so dire that panic cannot make it worse. There are two kinds of people in this world: those can extrapolate from incomplete data.
[XAP]Bob wrote:It took a good deal of strength, chainwhip and locking tool to get it off.
If we expect the friction between the cassette's 'cogs' to significantly load share then we're into the realm of lots of interesting engineering calculations Send a pic to ICE and see what they say - and let us know too
I agree about the inability of load sharing like that. It was just an idea, but thinking about it, it couldn't work.
However, as the cogs are held tightly, there wouldn't be any backlash as the cogs wouldn't rattle. But, as Bob's were tight, that's another red herring in this case.
Therefore, it can only be that the freehub unit isn't man enough for the job or the splines are incorrectly designed.
This happens all the time in modern racing wheels where aluminium (shimano splined) freehubs are specified to lose some weight. An aluminium (shimano splined) freehub body is not hard enough to resist indentation from seperate cogs. This is why shimano have changed the freehub design for the most recent high end 10 speed stuff. The new design has much deeper splines, similar to the superior design of MickF's Campagnolo hubs. This should prevent indenting as there is a larger surface area. The new shimano design is a pain in the bum as you can't fit old cassettes, so if a wheel is advertised as 10-speed specific, don't buy it for your 9-speed bike. You can fit the new 10-speed cassettes to old-design freehubs though
Last edited by AndyA on 6 Feb 2011, 2:00pm, edited 1 time in total.
You may not be able to remove your cassette after a fashion if the sprockets have worn deep enough indentations. It takes two chainwhips and a lot of fiddly jiggling sometimes
I've emailed ICE, and included a link to this thread.
Bob
A shortcut has to be a challenge, otherwise it would just be the way.No situation is so dire that panic cannot make it worse. There are two kinds of people in this world: those can extrapolate from incomplete data.
On my cassettes - all or most - of the cogs are separate flat discs, so are the spacers.
However, when you tighten the lockring, the whole lot is sandwiched tightly together to form one solid mass. This solid mass spreads the load on the splines evenly.
Perhaps Bob's lockring wasn't tight enough and his sprockets were slightly lose.
Even when the cassette is fastened with rivets or bolts, the main force transmitting the load from one sprocket to the rest is friction. This is why the makers stipulate a high torque for the lockring. This is not to stop the cassette from coming apart; but to ensure an adequate friction between the various elements. The deforming of the plastic spacers under a torque load means that even then the load will only be spread to to one or two sprockets either side of the one in use; but this is enough to avoid the deformation of any decent quality hub. My Shimano LX freehub is now on its third cassette and shows no sign of deformation even with the high torque of a 110kg load and a 25/34 drive train.
The lockring and smallest socket have facing teeth, so measuring the applied torque is hard, but it's back on tight again. For the commute (with the b chain.)
I shall wait for the official word.
A shortcut has to be a challenge, otherwise it would just be the way.No situation is so dire that panic cannot make it worse. There are two kinds of people in this world: those can extrapolate from incomplete data.
My email wrote:I've done ~600 miles on my trike now, and loving it.... However my local bike shop has only just managed to source a locking tool, so I've only just taken the cassette off for a good post winter clean.
Having not played with freehub much before I decided to check my findings with the CTC forums first...
<Link to this thread> If you click on the photo then the rest of the cassette is photographed in there as well.
Are we right to be concerned? I'll be taking it off for another clean in a couple of months (weather dependant) so can see how it progresses...
ICE wrote:This is normal although I can see why you would be alarmed, this is what happens with steel individual rings on an alloy freehub, it does not cause any harm and should not progress much further, the teeth tend to dig in from 1 to 2 mm and then do not move any more, when you do re assemble the cassette please make sure to tighten the lock ring down firmly as this will help to stop the rings from moving as much. We have had people ride tens of thousands of kilometres using this setup and while it does dig in as you have shown the cassette continues to function. If you notice a change in shifting please check the cassette as this could be a sign of further damage.
It is not, as someone on the forum put it “only fit for scrap”. far from it. <Manufacturer>, who make our hubs, use the same material for all of their freehub bodies.
In a couple of months if the damage is much worse then send us an email and we will replace your freehub. Thanks
I shall check when I next clean the cassette...
A shortcut has to be a challenge, otherwise it would just be the way.No situation is so dire that panic cannot make it worse. There are two kinds of people in this world: those can extrapolate from incomplete data.
[XAP]Bob wrote: To get down to a 9 tooth high gear (smaller than the splines) the highest few sprockets key into each other, which puts the load from any of those onto the end 2? sockets on the splines. But that's still not amplifying torque.
Surely this is the culprit? are we saying the smallest sprocket doesn't fit on the splines, but instead uses the previous sprocket for locating?
[XAP]Bob wrote: To get down to a 9 tooth high gear (smaller than the splines) the highest few sprockets key into each other, which puts the load from any of those onto the end 2? sockets on the splines. But that's still not amplifying torque.
Surely this is the culprit? are we saying the smallest sprocket doesn't fit on the splines, but instead uses the previous sprocket for locating?
Yes, although of course that reduces the torque, it does increase the time spent on that spline/hub interface.
I might even make a few intermediate checks...
A shortcut has to be a challenge, otherwise it would just be the way.No situation is so dire that panic cannot make it worse. There are two kinds of people in this world: those can extrapolate from incomplete data.
A shortcut has to be a challenge, otherwise it would just be the way.No situation is so dire that panic cannot make it worse. There are two kinds of people in this world: those can extrapolate from incomplete data.
Send a pic to ICE and see what they say - and let us know too 
