Bicycle Mechanics - carbon post and steel frame problems?

I weigh 218 lbs ( I heard my weight is the issue. I'm working on that). My new carbon post slides down in the frame an inch or so. I cannot tighten it enough. In fact, I left a tiny indent in the carbon trying to tightening the collar. There is no quick release. The inside of the seat tube is smooth. I replaced the collar. It looked a little warped, but the problem remained. I replaced the post with aluminum. Problem solved.... The post and frame are MASI. Any suggestions or words of wisdom are appreciated...

Sounds like you solved the problem by changing posts. Are you looking for a solution that uses the carbon post? If so, in my opinion, I think you are better with the aluminum.

http://www.cyclingnews.com/tech.php?id=tech/2006/news/10-25

I was hoping to utilize the carbon post that came with the bike, but the aluminum post works fine. The weight of the post is only about 20 grams heavier. I'm not really worried about that, but it is probably more a matter of wanting it to work. FYI. The diameter of the post and seat tube match up. I suppose I am curious about the failure of compatibility...

Pete Hammers link got it right on. The carbon is smoother and harder to get a grasp on, and once you do get a good grasp on it, it could compress just that tiny little bit to make it not work. The shop I frequent (although not for long) sells some grease that seems to have the consistency of locktite that fixes this.

I had the same problem on a new CF post to a new CF frame. Using a FSA post that I already had solved the problem: not sure if the FSA was a wee bit bigger but I think it was just becasue the surface was no longer as slick as a new post. Also, turning the QR so that the slot was opposite the slot on the bike helped me go feel more comfortable tightening it up without damaging anything--that and the fact that the FSA post seemed to be more than twice as thick.

So your saying it's ok to grease a CF seatpost? Did I misunderstand you?

So your saying it's ok to grease a CF seatpost? Did I misunderstand you?

Carbon Assembly Compound
http://www.cyclingnews.com/tech.php?id=/photos/2006/tech/news/10-25/FSAandTacxinstallationcompound

turning the QR so that the slot was opposite the slot on the bike helped me go feel more comfortable tightening it up without damaging anything

It's better to leave the slots aligned. With it flipped around, the clamping force is actually greatly reduced and can bend your seat tube at the front, where the clamping actually happens.

Did anybody put grease in the frame? That will cause a CF post to slip.
And measure your post O.D. with some mic's then measure the I.D of your seat tube. Even if the number is stamped it may be different.
The new stuff from FSA and Tacx is not a traditional grease based lube.

It's better to leave the slots aligned. With it flipped around, the clamping force is actually greatly reduced and can bend your seat tube at the front, where the clamping actually happens.

Well, aligning the slots goes against recommendations of CF seatpost mfgs (e.g., the installation instructions that come with Alien); however, I wouldn't want anyone to hurt their frame based on my post so please check that our for yourselves readers . . . :)

Well, aligning the slots goes against recommendations of CF seatpost mfgs (e.g., the installation instructions that come with Alien); however, I wouldn't want anyone to hurt their frame based on my post so please check that our for yourselves readers . . . :)

Really? Man. Carbon makes less and less sense all the time. So what if somebody decided to put a CF post on a nice steel or Ti frame where the clamp is integrated into the frame?

A quick search turned up that Campy recommended flipping the clamp for their thin CF post, which was cracking. From a mechanical standpoint, flipping a clamp is silly.

For a material that's claimed to be "stronger than steel," it seems weaker than sh*t. I'll admit that I only have CF forks and soles on my shoes, so my experience is limited. Everything else is steel, alu, or ti.

For $140-150, you can buy this -- http://tinyurl.com/y5vczd (or this http://tinyurl.com/y8nzzc) that will fix your CF seat post problems forever. After installing the product in the above link, you are guarenteed to have zero worries about CF breakages, and only need to use normal bike grease to install it -- no special CF-only goo needed.

After reading all the horror stories on CF seatposts, I am wondering if people should recommend the above product as a fix for any CF issues.

(Of course the product in the link is a Thomson Masterpiece seatpost...)

Really? Man. Carbon makes less and less sense all the time. So what if somebody decided to put a CF post on a nice steel or Ti frame where the clamp is integrated into the frame?

A quick search turned up that Campy recommended flipping the clamp for their thin CF post, which was cracking. From a mechanical standpoint, flipping a clamp is silly.

For a material that's claimed to be "stronger than steel," it seems weaker than sh*t. I'll admit that I only have CF forks and soles on my shoes, so my experience is limited. Everything else is steel, alu, or ti.

I think it's just a matter of followng the best practices for the materials that you are using, e.g., for a aluminum seatpost in a steel bike, you really need to grease things up. Let's face it, compressing a slot on the frame of a bike to bind a post is not evolutionary technolgy that we're working with here.

http://www.cyclingnews.com/tech.php?id=tech/2006/news/10-25

Great info. Where can you get the stuff?

I think it's just a matter of followng the best practices for the materials that you are using, e.g., for a aluminum seatpost in a steel bike, you really need to grease things up. Let's face it, compressing a slot on the frame of a bike to bind a post is not evolutionary technolgy that we're working with here.

I agree. It's just nuts that we have to reinvent the clamp just to save a few grams on a seatpost. Then you have to use a collar instead of an integrated clamp, which adds grams right back on. Plus the extra length of seat tube at the top to accomodate the collar.

If it ain't broke...