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carbon seatposts in carbon frames - TLC?



 
 
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  #11  
Old July 11th 05, 01:56 PM
Qui si parla Campagnolo
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Default carbon seatposts in carbon frames - TLC?



Mike Jacoubowsky wrote:
No defense necessary. I just like explanations for things so I
understand. Just because someone (even the "experts" at Campagnolo) said
so carries little weight, in my mind. Personally, I don't understand how
turning the clamp around 180 degrees will help. The inner diameter of the
seat tube must be reduced somehow to clamp the seatpost, and I don't think
compressing the seat tube is the better alternative. The diameter has to
be made smaller, and that's what the split clamp does. Unfortunately, it
also provides uneven, point loading at the edges of the slot.


Robin: Peter's correct that it's generally a good idea to reverse the seat
clamps. The problem comes when the slot in the seat clamp lines up with the
slot in the frame. In both cases they try to deform (point load, as you
mention), increase pressure on that one particular spot. You don't want to
increase pressure on a spot that's already suffering from increased
pressure, and keeping the slots from lining up prevents that. What Trek is
doing now is creating a seat clamp that has a diagonal slot, so it can still
be placed normally (without putting extra pressure right on the edge of the
frame slots).



Gee just like the one from Campagnolo, ya know Robin those 'experts'
that don't know anythin? I guess if it's from Trek, it's a good idea
but if from Campagnolo, bad idea to you.

--Mike-- Chain Reaction Bicycles


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  #12  
Old July 11th 05, 05:41 PM
Mike Jacoubowsky
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Default carbon seatposts in carbon frames - TLC?

My LBS said I need to pull out my carbon post from my carbon frame and
wipe
both with clean dry cloth every 1-3 months or riding (particularly if I

ride
in wet weather) to avoid the two "fusing" together permanently (very
expensive situation since crushing carbon seat post would be the only way
out in such a situation).

Put grease on the carbon post, and it'll glue it to the frame, and then
you won't need a clamp.


Not true. Grease on a seatpost will cause it to need too much clamping force
to hold it in place, which will damage the seatpost. Some carbon frames are
treated with a process that isn't grease-friendly, but it won't cause them
to weld in place as far as I know (nor have I seen this happen due to
grease).

There is a permatex gasket sealer product that can be used as a grease
substitute though. The only reason why you might use it is because grease or
the gasket sealer will help to keep water out of the seat tube.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com


  #13  
Old July 13th 05, 10:44 AM
Yuri Budilov
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Default carbon seatposts in carbon frames - TLC?


"Yuri Budilov" wrote in message
...
I don't know the answers to your questions but I had a carbon Specialized

Roubaix with carbon seat post and their instructions were exactly as the
first reply said - bolt to be on the opposite side to where the
crack/slit/whatever in the seat tube is - to prevent crashing the post. So
I asked my LBS about this rule for Trek Madone and they said that Trek
instructions were to place the bolt on the same side as crack/slit/etc not
on opposite side. This is very puzzling for me too! But I hate to break
Trek warranty by spinning the clamp around 180 degrees. Perhaps someone
can send Trek support an e-mail question? I would if I knew where to send
it to.....



I sent e-mail to Trek Australia yesterday and they said it does not matter
either way and there is no preference on their part re clamp bolt and split
as far as crushing seat post goes....


 




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