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Discussion Starter · #1 ·
Hello all,
I've got a (new for me) 2007 Cannondale Carbon Rush, and the Thomson Elite seatpost has no QR. I can afford a Dropper at some point, but I'd like to refrain from shelling out $300 when a QR clamp is 100x less. I've read that most QR releases cause damage/warping to carbon fiber frames. Is this the case? If so, are there any clamps that don't have these problems? I'd like some adjustability, but (like I said) I don't really want a Dropper seatpost right now. Thanks in advance!
Dan
 

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I've never read that before(haven't looked into it), but I built up a new carbon frame recently and it was supplied with a QR seatclamp. Use some carbon assembly paste to help with slipping and don't overdo the clamp tension.

You could get a solid dropper for around $200 -- the KS i950 lever version comes to mind. So, about 8x the cost of a good quality seatclamp.
 

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El Gato Malo
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As above, if you get a QR don't use your gorilla paws to over tighten. It doesn't take much clamping force to keep your seatpost from slipping.
 

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Discussion Starter · #4 ·
Thanks. Do you know of any consistently good clamps that are of these measurements: 27.2" ID 31.4" OD? I'm not necessarily looking for the highest quality and performance at the highest cost, just something reliable that works well. Thanks again!
 

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27.2 is the seatpost size. Measure the OD of your frames seattube.

Not much difference when it comes to seatclamps. I'm partial to Hope, but they're spendy and you could find something half the price that will do the job. More importantly, is a good fit between seatpost and seattube -- ideally, the seatpost should not slip right down when installed. Sometimes tolerances aren't great and that's what leads to slipping issues.

Sent from my SCH-I605 using Tapatalk
 

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Discussion Starter · #6 ·
Thanks. I've measured, and those are the measurements that I need. So pretty much any clamp will work as long as I don't tighten it too hard?
 

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Only one measurement is useful when it comes to seatclamps. Again, 27.2 is a seatpost size and 31.4 is not a seatclamp size. You're likely looking for a 31.8 or 32, given your 31.4 measurement. Maybe it would be worthwhile to take the bike to a local shop to get the proper size.

Sent from my SCH-I605 using Tapatalk
 

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Discussion Starter · #9 ·
Hello again,
Yes, you were right. I misread the Cannondale manual and 31.8 is what I need. Do you know how much force it would take to cause any actual damage? Would it be a realistic fear, or just something that COULD happen? Also, what carbon frame do you have that came with a QR?
Thanks!
 

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My Santa Cruz Tallboy LT carbon came with a quick release clamp, even though it has a dropper post, so I don't really see the point of it :)

A quick release clamp does the exact same thing as a non-quick release clamp. With either, they cause no problem until they are over tightened.

Here's the tricky part - One time, on an aluminum framed bike with a carbon seatpost, I was riding in muddy conditions. The post got dirty and I adjusted the height. The dirt on the post increased the diameter enough to crack the post. I didn't even notice it until I got home. It might not have cracked until after I started riding on it. A couple of long vertical cracks clean through that FSA post, but it still held my weight for maybe 7 miles of off road riding.
 

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Would the same thing happen with carbon frame and aluminum seatpost?
In general I would guess that the seat post is more vulnerable than the seat tube, because the post supports the tube. The slot at the top of the seat tube allows for considerable flexing when clamping the post. The seat post however, won't flex when clamped, it will eventually crush.
But dirt at the interface will cause concentrated stress where the dirt is, so could contribute to damage of either the post or the tube.
 

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Discussion Starter · #14 ·
In general I would guess that the seat post is more vulnerable than the seat tube, because the post supports the tube. The slot at the top of the seat tube allows for considerable flexing when clamping the post. The seat post however, won't flex when clamped, it will eventually crush.
But dirt at the interface will cause concentrated stress where the dirt is, so could contribute to damage of either the post or the tube.
So essentially what you're saying is that as long as I keep seattube and seatpost clean, there should be no major problems?
 

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So essentially what you're saying is that as long as I keep seattube and seatpost clean, there should be no major problems?
Yeah just don't do anything stupid. You shouldn't have to force a quick release closed. Sometimes they get out of adjustment. If it feels tight, loosen it, don't force it.

And if you have post slipping problems, get some paste. Don't try to fix the slipping by over tightening. Again, this would be true for a non quick release clamp as well.

A little common sense and you can use a quick release clamp on carbon for years with no problems.
 

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Like said before, a QR clamp can exert the same force as a non-QR clamp. Just don't overdo it. That said, i can't drop my seat with a QR while rolling. So, i love my dropper posts.
 
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