Ottrott seatpost issues

SummitAK · #1 06-23-2008, 04:53 PM

Dan's post on carbon fiber seatposts reminded me to check in with the forum about some issues I'm having with my Ottrott. The bike was picked up fully built after light use by it's original owner. It came with a zero-offset Easton EC-90 seatpost. This is the "D-shape" post with the relief cut molded into the rear of the post.

I experienced some intial seatpost slippage during my first few rides. I cleaned the seatpost and seattube then reinstalled using FSA carbon paste. This cured the slippage issue. Later inspection revealed that the titanium seattube edges at either side of the tube cut had worn into the Easton post. My first thoughts were that this occured because the Easton post shape allowed the seattube to be clamped out-of-round; and perhaps the seattube edges were not properly chamfered. The Serotta clamp also came very close to fully closing the gap across the clamping bolt (ie. both sides touching).

I didn't feel good about continued use of this post. Though from a structural standpoint it wasn't cracked. And the resin on this one appeared especially thick over the carbon fiber because even with deeply worn gouges the wear stopped at the carbon fiber surface.

Since I was also interested in some slight fit changes that the zero-offset didn't allow, I went to a new FSA carbon post with 25mm offset. I cleanly chamfered the seattube interior edge using a file and then sand paper. Used the carbon assembly paste again. And a torque wrench. I did not torque it to the 10Nm number I've seen listed for seatpost clamp torque. I don't recall the torque I used, but it was substantially lower than recommended. Again the Serotta clamp came very close to fully closing when torqued down. With the Easton I had assumed it came from the D-shaped post allowing more clamp closure than with a round post.

After the Easton experience I kept a close eye on the FSA. The same issue occured with the round FSA as had happened with the Easton. Wear at the rear, either side of the seatpost clamp cut. The FSA wear occured much quicker than it had with the Easton.

That was it for me. The carbon posts, especially the FSA, looked very nice with the Ottrott's carbon tubes. But I had to assume the carbon post wear would become a safety issue later. I picked up a Thomson Masterpiece with setback. I lightly greased and installed the post. The recommended torque took it close clamp sides touching again. During my first long ride the post slipped. It also scrubbed a noticeable amount of the rock hard Thomson anodizing off the post. I've run these posts for years in my MTB's and seen less anodizing wear.

I also had an intermittent creak that went away with the Thomson. Previously I was convinced it was coming from the front end as I thought it was happening standing as well as seated. And it sounded like the headset area. This really illustrated how difficult these things are to pin down.

Anyway I wanted to check and see if anyone has had a similar seatpost issue with their frame? Could this be the result of damage to the seat clamp in the past? My wife has a Legend and the Serotta clamp has much more space across the bolt/clamp gap after torquing than the one on my Ottrott. The Serotta clamps have less surface (thinner top to bottom) area than some aftermarket options. Should I try a replacement Serotta or aftermarket clamp? Stop greasing the Thomson and/or use the carbon friction grease?

I am in the clydesdale range with riding weight ranging between 200 and 215 in the 18 months I've had the Ottrott. This might be an issue with the CF posts, but shouldn't be for the Thomson. The Ottrott has the 8.5 tubeset layup and 8.5 fork.

Sorry for the long post and thanks for any help you can offer...

Charles M · #2 06-23-2008, 05:47 PM

A few frame manufacturers have taken to making 2-3-4 cuts in the seat tube material at the clamping area.

Personally I cant think of why anyone still has a single cut seat tube as having a couple lets the material better wrap to the post...

I've broken an easton seat post too.

but I've not broken any item that I have used carbon paste and a torque wrench on. Neither have I had any slipage where I have used carbon paste and a torque wrench.

All that said, I believe there is also a difference in the mount of torque required to make some clamps tight versus others as frictoion varies with lubricant and tollerance

SummitAK · #3 06-26-2008, 01:00 AM

Thanks for the input Charles.

Anyone else have any similar issues? If not the seatpost wear how about the post slippage and lack of clamping force?

I am going to try a new clamp. I thought there would be more options available, but reviews seem to indicate I should get another Serotta clamp or try the Campy version.

I measured the seat post in front to rear and side to side with calipers. This yielded 31.17mm and 31.50 for an average of 31.33mm. Most of the clamps list a tolerance in the range of 31.6-31.9. So maybe this is part of my clamping issue?

duke · #4 06-26-2008, 10:26 AM

I have had the same issue you describe with my 02 Ottrott. I have only used a Thompson Elite post and have not been able to secure it tight enough to keep it from slipping or creaking. I don't have a torque wrench but I eventually clamped the Serotta clamp tight enough that I stretched the bolt. The seat still creaked and eventually slipped. I tried an IF clamp that I had and the same result. I haven't tried another post yet and presently I am not at home so the project is on hold. This has been an issue for the six months I have had this bike. I'm sure there is a solution, I just haven't come up with it yet. Let me know how your saga evolves.
duke

Mike748 · #5 06-26-2008, 11:07 AM

Could the seat tube ID be too large? Easy to measure with a bore gauge. If so, maybe try a 27.4 seatpost?

Another thought... seems like my Ti Fierte has an insert in the top of the seat tube that is perforated with 1/4" holes. I assumed this is to reinforce the seat tube and keep the titanium tube from welding to the seatpost. Not sure how this is inserted, but maybe it can slip down and get out of position?

CaptStash · #6 06-26-2008, 08:58 PM

I happened to be talking to Duke today so I was thinking about this problem. Based in the fact that Duke, even after over-tightening his seatpost clamp had a similar problem, and the OP's description, it seems clear that the i.d. of the seat tube is just a hair large. The question then becomes: how do you fix that? Using a 27.4mm seat post would work if you could find one. I suspect 27.4 would be just a little big, and you'd have to make it smaller which is no mean feat with an aluminum post, although a carbon post could probably be sanded down until it just fits.

If it were me, I would try going low tech first. Try carefully wrapping the post with just enough teflon tape so that the post will go in (just barely) without tearing-up the tape. Then clamp it and see what happens. Hell, try electric tape for that matter. maybe just one or two then longitudinal electric tape shims will cure the problem and let you get back to the business of enjoying your bike.

CaptStash....

SummitAK · #7 06-27-2008, 01:20 AM

Thanks for the additional recommendations.

My Ottrott does have the sleeve Mike describes for his Fierte. It appears to be fine. I measured the I.D. of the seatpost and it seems to be in the 27.2 range. Getting a tight measurement with the inside calipers is more difficult than the O.D. measurement. The Thomson came in around 27.17 so it is probably within tolerance too.

I'll try the new clamp and and some insurance with the carbon paste.

Thanks

SummitAK · #8 07-07-2008, 09:02 PM

I picked up a new Campy clamp. This is the model with the offset clamp split which is not lined up with the seattube clamp relief cut. I lightly greased the Thomson and torqued the clamp to 10N-m. Then I went for a ride. The post started slipping almost immediately.

I removed the post, cleaned the grease out of the seattube and off the seatpost then reinstalled using FSA carbon friction paste and same torque spec. The paste made the seatpost noticeably harder to insert. I went for a ride and the seatpost creaking started immediately. It may just be my irritation, but the creaking seemed to get worse over the duration of the ride.

The post did not slip at all during this ride. I'm not sure what would happen over time, but I can't handle the creaking anyway. I'm not sure what to do at this point. I could go back to the carbon post as the creaking is less noticeable. But in the long term the carbon post may fail.

Capt Stash thanks for the shim suggestion, but I don't think either teflon or electrical tape would have enough bite here. They probably wouldn't fit either. It is almost like the seattube in this area is slightly conical. That is tigher near the top and then opening up deeper in the seattube which allows the seatpost to shift around.

I will try to check with Serotta about checking tolerances on the frame. Maybe there is a method for repairing this at the factory? As Duke has the same problem this can't be the first time this issue has come up with Serotta.

Thanks

ecl2k · #9 07-07-2008, 09:15 PM

I would use a good shim made by someone like USE and downsize to a smaller diameter aluminum or titanium post. Use a good seatpost clamp with a stainless steel bolt and torque it down. It's kind of a kludge but it should work. The shim has a lip at the top so it won't slip down into the frame.

http://www.use1.com/products/seat_post_shims/index.php

You could also fool around with some metal cutters and coke can and try to fashion a very thin shim out of it but I like the above approach better.

Brian Smith · #10 07-08-2008, 09:24 PM

Many seatposts labeled or sold as 27.2mm do not actually measure 27.2mm. It is a commonly held opinion that carbon posts are some of the worst offenders in this regard. The L.H. Thomson posts seem to have very good quality control, however their intention is to always deliver substantially less than 27.2mm on a post labeled "27.2mm," even less than other brands. Your Serotta isn't intended to work with undersized posts, such as a post measuring 27.09mm.

After being sure that you have a post measuing between around 27.15mm and 27.20mm, I would suggest going overboard with your seatpost clamp for a time period sufficient to eradicate any notion that an ill-fitting post is your culprit. A number of companies offer clamps for a 31.8mm seat tube which offer even more clamping power than the stock clamp, but are also heavier. Their temporary use could help ascertain that the clamping problem is with your original seat post clamp, and not in fact due to your post or your frame. It's a little known fact, but Serotta actually provides a slightly larger diameter clamp with painted frames than they do with unpainted (polished, stain, or matte) frames, and such a clamp, in my experience, is a second class fit on an unpainted frame, producing less clamping power than the intended clamp. The difference between the clamps is much less than the range of actual diameters of seatposts labeled "27.2mm," but if you do find that a beefy replacement clamp solves a problem, then perhaps you simply ended up with the wrong size clamp.

So, if you'd rather not send your frame off for evaluation, those are things you could investigate on your own:

Seatpost between 27.15mm and 27.20mm
Seatpost clamp of the style "bulky and crude, but effective"

ecl2k · #11 07-09-2008, 12:52 PM

"Seatpost clamp of the style "bulky and crude, but effective"

Pete Serotta · #12 07-09-2008, 02:19 PM

Brian really knows his stuff.

If you tell us where you live, we (FORUM)may be able recommend a shop that can take a look at it. (any good shop can also.)> I personally have never has any problems over the years with Thomson, Easton (except a break), Campy, or Ritchey, and have had more than a few Serottas. The CAMPY clamp is excellent as a rule, so see how that works for you. The 200 lbs should be fine - - a good buddy of mine has two new bikes with the RITCHEY and SEROTTA clamp and no problems.

While this does not address your problem, hopefully we can get to the bottom of it via CAMPY clamp or a trip to dealer.

PETE

Quote:

Originally Posted by SummitAK

I picked up a new Campy clamp. This is the model with the offset clamp split which is not lined up with the seattube clamp relief cut. I lightly greased the Thomson and torqued the clamp to 10N-m. Then I went for a ride. The post started slipping almost immediately.

I removed the post, cleaned the grease out of the seattube and off the seatpost then reinstalled using FSA carbon friction paste and same torque spec. The paste made the seatpost noticeably harder to insert. I went for a ride and the seatpost creaking started immediately. It may just be my irritation, but the creaking seemed to get worse over the duration of the ride.

The post did not slip at all during this ride. I'm not sure what would happen over time, but I can't handle the creaking anyway. I'm not sure what to do at this point. I could go back to the carbon post as the creaking is less noticeable. But in the long term the carbon post may fail.

Capt Stash thanks for the shim suggestion, but I don't think either teflon or electrical tape would have enough bite here. They probably wouldn't fit either. It is almost like the seattube in this area is slightly conical. That is tigher near the top and then opening up deeper in the seattube which allows the seatpost to shift around.

I will try to check with Serotta about checking tolerances on the frame. Maybe there is a method for repairing this at the factory? As Duke has the same problem this can't be the first time this issue has come up with Serotta.

Thanks

SummitAK · #13 07-10-2008, 02:35 AM

Brian and Pete,

Thanks for the suggestions. If you look through my earlier posts I think you'll find I've already tried most of what you suggest. Measurements (Thomson = 27.17), seatube o.d. (31.33), seattube i.d. (approx. 27.2). Campy clamp, etc. From my earlier measurements, the o.d. of the seattube appears a bit small versus the listed clamp tolerances. But I have not tried a Serotta replacement clamp in the version for unpainted frames that Brian mentioned. I will see about ordering one of these. I think Pete listed a Serotta contact and extension for ordering a clamp in another thread.

The shop options here are very limited. The AK in my username is Alaska. I'm in Anchorage. The Serotta dealer is a personal friend. He has not carried the brand long nor spec'd many of them for customers. He was impressed with the build my wife received on her Legend from PK in Marin and now carries the line and is ordering a Serotta for his personal ride. I don't think they'll have any machine tools beyond what I have access to or own.

ecl2k, your shim idea might work, but I'd rather avoid dealing with the issue that way. And that galvanized muffler clamp doesn't have enough bling

Thanks

Pete Serotta · #14 07-10-2008, 05:02 AM

See email that I sent to you....PETE

Quote:

Originally Posted by SummitAK

Brian and Pete,

Thanks for the suggestions. If you look through my earlier posts I think you'll find I've already tried most of what you suggest. Measurements (Thomson = 27.17), seatube o.d. (31.33), seattube i.d. (approx. 27.2). Campy clamp, etc. From my earlier measurements, the o.d. of the seattube appears a bit small versus the listed clamp tolerances. But I have not tried a Serotta replacement clamp in the version for unpainted frames that Brian mentioned. I will see about ordering one of these. I think Pete listed a Serotta contact and extension for ordering a clamp in another thread.

The shop options here are very limited. The AK in my username is Alaska. I'm in Anchorage. The Serotta dealer is a personal friend. He has not carried the brand long nor spec'd many of them for customers. He was impressed with the build my wife received on her Legend from PK in Marin and now carries the line and is ordering a Serotta for his personal ride. I don't think they'll have any machine tools beyond what I have access to or own.

ecl2k, your shim idea might work, but I'd rather avoid dealing with the issue that way. And that galvanized muffler clamp doesn't have enough bling

Thanks

pure-james · #15 10-12-2009, 04:38 PM

I have a serotta legend, and my Thomson Elite seatpost keeps slipping and this has been going on for a long time but has become significantly worse in the past few months.

A few weeks ago I bought a torque wrench and took the bike apart reapplied lube or copper slip where needed and did everything back up to correct torque (I was surprised at how much force was needed for 7.7Nm). Everything except the seat post was perfect, but after half an hour of riding the post had slipped down again.

I do not want to over tighten the bolt, so are there any other suggestions or does this require a trip back to cyclefit?