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PostPosted: Fri Oct 17, 2014 12:14 pm 
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Joined: Fri Oct 28, 2011 3:25 am
Posts: 853
Location: United Kingdom of Great Britain and Northern Ireland
I really object to having one break after having crested a climb over 1000m - new pair of Campagnolo wheels. But I am interested why this would have happened. It must have broken on the way up the climb but went unnoticed until I tried descending and when the freehub would not rotate backwards.

Not had one of these break before, but I am inclined to think that the old design with the three separate springs was a more durable design. Perhaps there is a good reason why Campag sell replacements in packs of five.

Thanks for any comments.


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Posted: Fri Oct 17, 2014 12:14 pm 


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PostPosted: Fri Oct 17, 2014 1:08 pm 
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Joined: Thu Sep 04, 2014 12:23 pm
Posts: 187
I have ridden Campy wheels with both freehub spring designs for decades and never an issue. Hard to say why the band style single spring broke. No doubt there have been hundreds of thousands of miles of testing on it. Hopefully it was just poor metallurgy for that example and won't happen again. If the band spring had broken on the way up, not sure you would have made it. Compression of the band is what pinches the cammed detents outboard and engages to the hub. If the band breaks the detents will slip.

The style you have below:

Image


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PostPosted: Fri Oct 17, 2014 7:22 pm 
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Joined: Wed Apr 25, 2007 10:23 am
Posts: 711
Location: Pack filler
I've had quite a few break over the years on different level hubs (mirage - record, r7 etc), including one broken from new, so its definitely not an isolated case.
KT hubs had a similar design and I cobbled some of them with the campag springs.

My guess is that the grooves aren't machined too well in the pawls, and snag.

On the plus side, they're cheap, and easy to replace. Better than some gummy thing that's sealed and deteriorates further.

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PostPosted: Fri Oct 17, 2014 8:00 pm 
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Joined: Fri Oct 28, 2011 3:25 am
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Location: United Kingdom of Great Britain and Northern Ireland
highdraw wrote:
If the band spring had broken on the way up, not sure you would have made it. Compression of the band is what pinches the cammed detents outboard and engages to the hub.


When the spring breaks the pawls stay in the sticky-out position, so forwards drive is possible. It is only when you try and turn the pedals backwards you find that the freehub does not rotate backwards properly. After the spring broke my freehub became stuck as if I was riding fixed wheel, but after some hand pressure I managed to loosen the freehub so that it would rotate backwards.

And the old style 'box of frogs' system seemed to work with more pressure/positivity.


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PostPosted: Fri Oct 17, 2014 10:55 pm 
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Joined: Thu Sep 04, 2014 12:23 pm
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Thanks for the correction Valbrona if its true. ;) What do you suppose the physics is for holding the pawls in an extended state when the spring breaks which is designed to provide preload to that effect? I suppose centrifugal force may throw them into that position and then interference to the ratchet of the hub may keep them engaged. I have never broke one.


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