nadimk

I love carbon seatposts for the way they feel. I have the old Enve single bolt and it is starting to slip and now will not stay level despite torqueing and carbon paste. The question I have is what carbon posts do people like for their clamping mechanism? Is single bolt universally bad? Has anyone used the Zipp SL speed carbon post? Thanks!

king_solom0n

I have the Deda Superleggero RS seatpost. Only had it for a few months but no issues so far.

noodle soup

I've had good luck with this style of post.

https://www.ebay.com/itm/Full-Carbon...lmUFkolerp_D_w

Sy Reene

evan326

I've got one similar to what @noodle soup posted, never slips.

NILS14

Fizik's clamping system is wonderful to use. I also like the FSA K-Force and it's available in a 32mm setback as well.

Jazzguitar

JohnJ80

Me too. The Cyrano 00 is a brilliant seatpost. I just got one to replace a problematic Ritchey Flexlogix post that was slightly undersized and insisted on slipping (it goes egg shaped as it flexes fore and aft and then slipped). I had been a Fizik Cyrano fan for years (in Al) because their clamp is probably one of the easiest to adjust and one of the best out there. What really surprised me is that the 00 has such great vertical compliance - better than the Ritchey! So it's my new goto seatpost. The tilt adjustment is terrific (red arrow). You can easily dial it in and then move it tiny amounts from there.

Recommendation if you decide to get one - disassemble the seat post and lubricate/grease the bolt mounts indicated by the blue arrows. They can creak or squeak as the post flexes if you don't. Don't know why Fizik doesn't do it at the factory. I put some PTFE lube in there and it worked great.

DrIsotope

FSA SL-K SB20 ITC. Can be found for around 50 bucks, and uses a three bolt clamp-- one bolt for each rail, and one bolt to set the saddle tilt. That's right, you can change setback without messing with tilt, and vice versa. Fits round or oval rails.

chaadster

Good reccos above, and I'll +1 the Deda Superleggero and FSA SL-K (though I use a 2-bolt variant). I use both, and actually have two of the SL-Ks in service. If I want to save weight, Deda, and if I want to save money, FSA!

mitch2

My new Fizik Cyrano seatpost loosens at the seat clamp during 3 of 3 rides so far. I am fortunate to not have been on a group ride. To make matters worse, I thought the bolts were No. 3 hex size but just found out tonight they are 1/8 inch hex...who uses a 1/8 inch sized hex?!? Who carries one on their bike, duh, I do now! Found owners with similar problems over at The Paceline forum and it seems they are using Loctite - sheesh! Shouldn't pay 2+ bills for a seatpost and then have to tighten it every ride. Have Tompsons on 3 other bikes and never realized one could have problems with a stupid seatpost.

Sy Reene

Never heard of this issue with Cyranos. Found one person on Paceline who mentioned this, nobody else. R1 specifies 8nm torque though I've been fine at 6nm. This may be higher than other brands' clamps since the clamping surface area is larger than most (ie. a more spread out distribution of the clamping force).

My R1 uses a 4mm hex. I believe the 00 model uses a torx T25 head. No idea how/where you determined a 1/8" size?

Routine maintenance -- dissasembly and regreasing can help if there are creaks.

DaveSSS 

No seat post should use a 3mm or 1/8 hex wrench. That would usually go with 4mm bolts, not the normal 5mm. Maybe new bolts will cure the problem. I've used nothing but the FSA k-force for many years, on many different bikes. Always works perfectly.

mitch2

It is a new CYRANO SEATPOST 00 in the 31.6 mm size. My experience is related to the saddle rail clamp and NOT the seat post clamp to the frame. Both djg21 and JohnH posted on paceline about having the same loosening problem. I don't want a problem, but three times in three rides (with two different saddles) is a bit much. Creaking has not been an issue for me. I am not sure about the Torx T25, which would be too large for the saddle rail clamp bolts. Interestingly, I cannot find these sizes listed on Fizik's website so I started by trying my normal metric Allen keys (that work on almost everything else on my 4 bikes) and was initially able to use a 3 mm (0.118 inches) but it was loose. I found that a 1/8 inch (0.125 inches) Allen key fits much tighter and works fine. I believe the bolt heads may be set up to use either Torx or Allen but at T25 (0.173 inches) you must be referring to the seatpost to frame clamp bolt because that would be much too large for the seat rail clamp, which must use a T15 (0.128 inches). BTW, both saddles I tried have carbon rails, if that makes any difference. I have really liked the feel of the post for the miles I have successfully put on it but during each ride the saddle started wobbling around causing me to stop and find that the saddle rail clamp had loosened. Interestingly, after I tightened it last night I found there is a small amount of side-to-side movement and so I wonder if that is causing loosening of the bolts. I plan to ride again today and will first adjust the tilt and then use some loctite as posted by JohnH.

mitch2

I agree DaveSSS but a 4mm hex is for sure too large. Sy Reene is correct, it is not a 3mm, but it is also not a T25, which would be too big. It is either a T15 (0.128 inches) or a 1/8 inch (0.125 inches). My guess is that either will work.

Sy Reene

No.. I'm referring to the saddle rail clamp. A 00 Cyrano supposedly uses at T25 torx bolt. You also refer to 'bolts' -- there's really only I think one bolt that you typically tighten with a tool. It sounds like you're sticking a 1/8" allen key into a T25 head -- which fits somewhat, but is not a good idea at all; getting the right torque (up to 7nM for 00 I think is recommended) without rounding out the hole in the bolt is unlikely. A T25 driver is star shaped .173 measurement is from point of one star to end of the opposing star, not measured the same as an allen head. See pic below

Here's quick link to product description, which includes T25 mention:
https://www.biketiresdirect.com/prod...arbon-seatpost

Sy Reene

for comparison, here's what a 3mm vs T25 head looks like from my mini-tool. Sorry I don't have a 1/8" allen, but 3mm is close enough to give you an idea. You can see how you might get an allen about this size into the center of a T25's cutout, but not good.

DaveSSS 

A T25 head is quite common with an M5 bolt. That's what my Zipp stems use. They come with the T25 torx wrench.

RiceAWay

I have absolutely no idea how you can tell the difference in an Al and a CF seatpost through a saddle with any padding at all. Al seatposts such at Cannondale or Specialized are often lighter than a CF seatpost and they usually have much better clamping mechanisms than CF.

https://www.competitivecyclist.com/t...NjQ2F0MTAwMDg1

Sy Reene

Nobody's talking about the clamping of the seatpost in the frame. The discussion is now about the clamping of the saddle in the seatpost's clamp.

Atlas Shrugged

Canyon VCLS Carbon Post. Super comfortable post, defiantly will not regret it.

https://www.canyon.com/en-at/gear/co...st/148289.html

mitch2

test

mitch2

Sy Reene, you are indeed correct, this appears to be a T25 torx head. I tried a T15 which was too small and a T20, which "worked" but seemed a bit loose. I do not have a T25 torx here but I will get one. It seems in the Torx world, the dimension given (at least in the source I accessed) is the overall outside dimension of the hex stock prior to cutting the torx shape of the end. So while the T15 and 1/8 inch hex have almost identical overall outside dimensions, after shaping/cutting the head the T15 is actually much smaller and the T25 is the correct size. The 1/8 inch hex seems to work well to tighten the bolt but I will get the T25 because it will probably reduce wear on the bolt compared to using the hex key. Not sure why they wouldn't just use a standard metric sized hex like everyone else since those are the tools most of us carry to fix stuff when we are on the road far from home.

None of that has anything to do with why this connection keeps loosening up when I ride. I have ridden Thomson posts and stems for many years on all 4 of my bikes and have NEVER had one loosen up during a ride. I will if the loctite solves the problem but it will be difficult for me to ever fully trust this post. I do a long unsupported ride each summer and unfortunately, I will probably have a hard time trusting this post for something like that. I like things as simple as possible and carrying an extra (torx) key plus loctite in my saddlebags is not making things easier.
I tried to post a picture showing the "bolt" that came with my seatpost, but since I am new with less than 10 posts I was unable to either post it or send it to you by private email.

Sy Reene

Many mini-tools come now with a T25.. maybe time to get a new one :-) Search on Amazon for a "SKS Tom 7" for a minimalist one.

Is the actual bolt coming loose, or it stays tightened but the saddle is slipping? If the latter, try a little assembly paste on the clamping surface.

Otherwise, all I can surmise, is that one of only a few things is going on:
1. The bolt has never been able to be tightened enough (6-7Nm) using the allen key so it's just naturally jiggling loose. Getting a T25 tool may help. or
2. The bolt or the receiving 'nut' is stripped
3. It's possible you have a saddle rail shape that isn't supported by the fizik clamp so the rails are shifting and causing clamp to loosen. But this should be unlikely, I've used mine with round and 7x9 carbon rails without issue.

Basically there's nothing special about a bolt and the 'nut' it threads into, so there's not a design flaw as far as I can imagine -- so thinking there must be something else going on.

mitch2

I hear you and understand what you are saying, which is what makes this so frustrating. It is one or both bolts that are actually loosening up, and not the saddle shifting. The bolt was tight to begin with (to 7N-m as recommended) and the saddle was solid on the clamp with no shifting whatsoever. The shifting seems to begin after about 10-15 miles of riding (on paved roads - nothing unusual). The saddles used so far were a Brooks C13 with carbon rails and a Selle Anatomica with carbon rails. It happened with both. The back bolt has a washer that is beveled on one side so that it fits into a slightly countersunk opening on the little cylinder that extends through the back end of the post. There is no lock nut. The torx vs. hex thing is not the issue here but rather that the clamping mechanism will not keep the saddle secure. This will either resolve with loctite or I will sell it to somebody who likes these, put a Thomson back on, and move on. Too bad since it is a brand new post.