Clydesdales/Athenas (200+ lb / 91+ kg) - Carbon Seat Post Issue

I just posted on the Road Cycling forum about a seat post problem I'm having. My carbon seat post is pinched/crimped/bulged where the clamp tightens down. They confirmed that I should be worried, so I'm going to replace it... so here's my questions...

Has anyone else had issues with carbon seat posts? Any input from the manufacturers on max weight? I don't want to get another carbon seat post if my weight is just going to break it. I'm right at 245 so I'm OK with going to aluminum at least until I get down below 200.

Also, any input on whether carbon makes a big difference vs. aluminum? Is it a noticeably smoother ride?

Thomson! The Clyde Approved Gold Standard of posts.

+1 on Thomson.

I never have (or will) ride on carbon, so I can't compare.

I've been riding on a carbon post (came with my Lemond Buenos Aires) for 6 months, 1500 miles started at 275lbs down to 258 and no problems thus far.

To be honest, when I had my new bike built up, I wanted nothing to do with a carbon seat post after seeing one of the top guys in the TDF riding around the Champs Elysee with a broken carbon seatpost pointing like a dagger right at his *****.

Yeah, a titanium seatpost would probably be a better idea. When a seatpost fails, I want it to bend, or snap off clean, not turn into an ultra-sharp, ultra-strong dagger of evil and hate aimed at my undercarriage.

I like my Allez, it has an Aluminum post that is wrapped in CF. The Al will keep the post from shearing if it fails, and the CF adds some strength to the thin Al.

Yeah, a titanium seatpost would probably be a better idea. When a seatpost fails, I want it to bend, or snap off clean, not turn into an ultra-sharp, ultra-strong dagger of evil and hate aimed at my undercarriage.

Exactly! Not the best place to save a few grams.

Pinched/crimped/bulged doesn't sound like a rider weight issue. I know plenty of big guys riding carbon everything and they don't have any problems. I'm also friends with a 115 pound woman who just had a Bontrager carbon post replaced for the same issue you're having.

If the shop (or you, if you wrench on your own bike) didn't use a torque wrench when tightening the clamp, it's likely it was overtightened. Carbon parts are pretty finicky when it comes to unnecessary stresses, and they don't like to be overtightened. You may not see any damage initially, but the additional stress of rider weight will be enough to ruin the integrity of the part.

Not exceeding proper torque is important in any case, but even more so with carbon components. If your seat post clamp was tightened too much, and that's the reason for the bulging, then it may be damaged beyond repair. Use carbon assembly lubricant for carbon components and they'll stay in place without over-torquing.

+1 on the torque wrench. Bicycle "manuals" should come with a complete set of torque specs.

Most carbon seat posts really are not any lighter than good AL seat posts. A carbon seat post is mostly bling. well that and bike companies like to claim that the carbon seatpost will help dampen road vibrations much like carbon stays and forks according to one of the lbs i walked into :thumb:

There is no "need" for a carbon seatpost for clydes - only asking for trouble. I have not heard of a carbon seat post designed for heavy-duty. Let's face it we are not the target market for carbon parts.
Any quality aluminum seatpost would do (no need to shell out money for Thomson etc.. - after all it is only a seatpost not a religion). A few grams more certainly do not matter for clydes.
My bike came with a carbon-wrapped seat post. I am pretty sure these carbon wraps are merely for the looks.

Any quality aluminum seatpost would do (no need to shell out money for Thomson etc.. - after all it is only a seatpost not a religion).

The adjustability (both ease, consistency, and precision) of a Thomson is very nice. They're not particularly expensive either.

Any quality aluminum seatpost would do (no need to shell out money for Thomson etc.. - after all it is only a seatpost not a religion).

Blasphemer! :lol:

Actually, I've got $25 Kalloy posts on both my good bikes, and a generic (probably $5) beater post on my utility bike. I wouldn't mind a Thompson post, but I've been happy with the ones I've got.

The adjustability (both ease, consistency, and precision) of a Thomson is very nice. They're not particularly expensive either.
You can usually get all of these for at least half the price of a Thomson (without the fancy brand name of course). It is not rocket science, just a seatpost, nobody will notice the difference once it is under the butt.

I have a Thompson post as well. I like that it is light, easy to adjust and can take my weight that I do not have to worry about it at all. I have had other posts that I did worry about. I also have a Thompson stem and it does not flex at all and I am a pretty big guy.

There is no "need" for a carbon seatpost for clydes - only asking for trouble. I have not heard of a carbon seat post designed for heavy-duty. Let's face it we are not the target market for carbon parts.
Any quality aluminum seatpost would do (no need to shell out money for Thomson etc.. - after all it is only a seatpost not a religion). A few grams more certainly do not matter for clydes.
My bike came with a carbon-wrapped seat post. I am pretty sure these carbon wraps are merely for the looks.

The only ones that are adequate to supprt the weight of a Clude are the aero posts. If the post is not round, then it will have more lateral strength than a simple round tube.

So it sounds like the concensus is that the carbon seat posts don't do much for the vibration dampening that the mfg's claim. Am I reading you'all right?

I do believe this is an over-tightening problem. I've always used a torque wrench except if I'm tweaking while on a ride. I'd be surprised if my little pocket tool could give me enough leverage to cause that much damage, but maybe so. Then again, it only takes once to weaken something like carbon.

I've broken a couple of carbon seat posts from simply riding and I only weigh 170lbs.

Btw,Curious here, what's with the interest in carbon?
I mean concerning oneself with bike weight is simply ridiculous when said person on bike weighs 245lbs , no offense

Btw,Curious here, what's with the interest in carbon?
I mean concerning oneself with bike weight is simply ridiculous when said person on bike weighs 245lbs , no offense

Advantages it's lighter, although it can't be by very much, it supposedly is better at dampening vibration, although the seat rails which are slightly springy probably do more.

Disadvantages, it's easily damaged, damage can lead to catastrophic failure, and when a seat post fails, you better realise that your seat is gone before you sit, :eek::cry::twitchy:

To have a "comfortable" seatpost, it has to be primarily one thing: long.
The German magazine tour did a test with about 50 high end bike frames a few years ago and did measure the comfort (the vertical compliance of the bikes). Tests were without wheels. The single factor significantly influencing the comfort of a bike frame was the length of the seatpost/the geometry of the frame. There was no measurable difference between frame materials (aluminum, carbon; perhaps they did not have steel frames in this test).
If you want comfort, get a "compact frame" - I know they look somewhat funny.

varminter,
As stated in each of my posts, I'm asking about vibration dampening... it's not about weight. I've read and been told that the carbon seatpost dampens vibration. I'm asking if everyone agrees or if it's salesmanship. I only have experience with carbon because that's what came on my bike.

I loose more mass by sweating on a 40 mile ride than I loose by going carbon over aluminum. I couldn't care less about the weight savings. However, if it saves my butt a little numbness due to chipseal, then I'm interested in it.

Frankly, I've already decided on aluminum, but I was curious about everyone's opinions on the dampening.

No offense taken... because you are right in respect to weight. However, you really should read the questions before replying. It could save someone's feelings and keep you from looking foolish.

Thanks lutz. That's pretty interesting.

varminter,
As stated in each of my posts, I'm asking about vibration dampening... .
you really should read the questions before replying. It could save someone's feelings and keep you from looking foolish.
Oh eye see.:)