On Fri, 07 Jul 2006 09:42:59 -0700, Mark
<
[email protected]> wrote:
>jim beam wrote:
>> Bleve wrote:
>>
>>> Our local American Classic rep came in to the LBS on Wednesday, and
>>> showed us some new lightweight clinchers, which in itself was of no
>>> particular interest.
>>>
>>> *but*
>>>
>>> He also showed us some shims for their 9sp alloy freehub to make it
>>> work properly with 10sp casettes to avoid dig in like this :
>>>
>>> http://www.aboc.com.au/images/galleries/20060116-bontrager-freehub/DSCF6994.html
>>>
>>>
>>> We pressed him to see if AC would sell the shims as spare parts, and
>>> he'll get back to us on it. But, it may be a hack to get around the
>>> current problem with 10sp Ultegra & Dura-Ace cassettes on 9sp alloy
>>> freehubs.
>>>
>> a shim won't do it - it doesn't bear the torque load. they need to
>> address the problem properly like shimano did - make the teeth deeper or
>> use a steel/ti cassette body. have them do the math on the loading per
>> unit area of the cog splines on the aluminum cassette body. aluminum's
>> just not strong enough - as if that's not already evident.
>
>OK, sounds good, but all my Campy hubs have aluminum freehub bodies, all
>my cassettes are separate-cog (no carriers), and I don't see "digging
>in" - indeed, only mild blemishing. And that's with a 26T small ring in
>front and 23 or 26 in back, so you know the body gets plenty of torque.
>
>So why does Shimano have this problem and Campy doesn't, or am I the
>only Campy user who isn't chewing up his freehub bodies?
>
>Seriously curious,
>
>Mark Janeba
Dear Mark,
It may have to do with the reduced number of splines on the larger
Shimano rear cogs. They have only 6 splines, while the smaller cogs
have 9 splines.
This leads to these odd "shims" or "clips" from American Classic:
http://www.amclassic.com/tech/pdf/10-SpeedClipsDura-Ace.pdf
The three wide steel inserts are supposed to fit inside the larger
cogs, reach around between the cogs and the hub, and push against the
otherwise unused spline, turning them into 9-spliners.
Notice the almost ungouged spline in this picture:
http://www.aboc.com.au/images/galleries/20060116-bontrager-freehub/DSCF6987.html
It looks as if no cogs pressed against it. I think that the steel
inserts are supposed to reach around and push against it.
But the gouges on the hub seem to include the smaller 9-spline cogs,
not just the larger 6-spline cogs, so I wonder whether the problem is
really just that an aluminum hub is a bad idea.
I don't know if Campagnolo's larger cogs have fewer splines.
Cheers,
Carl Fogel
