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USE Alien 25 mm carbon seatpost and Look framesets(16 posts)

USE Alien 25 mm carbon seatpost and Look framesetsPaul
Jan 17, 2002 7:23 AM
This was dicussed several days ago.

Excel Boulderstates that the USE Alien Carbon seatpost (25mm) can't be used on the Look framesets. I contacted them, and they said that the wall thickness of the post is too thin, and the Look clamp could puncture the post. It's light (130 grams), and this could be a problem with any clamp. They have a seatpost in the standard size of 27.2, don't know if over clamping could break the post. Have to be careful with wall thickness when it comes to carbon, know of people cracking carbon steerers by over tightening the stem.

Paul
re: USE Alien 25 mm carbon seatpost and Look framesetsJimP
Jan 17, 2002 7:29 AM
I don't understand. The USE 25mm post uses a metal shim in the seattube and the clamp will touch that. I would check with Look themselves on this issue.
Think Look would know?Paul
Jan 17, 2002 7:53 AM
Look gives the torque spec for the seat post, don't know if they could answeror would answer about another brand. I was think about a shim for strength, but why bother when you can get the Look ergo post cheaper through totalcycling ($112.00) then Excel for $130.00.
re: USE Alien 25 mm carbon seatpost and Look framesetsJimP
Jan 17, 2002 9:00 AM
I looked at the specs for the Look carbon frames and they use a 25mm seatpost. If the clamp is internal, then Excel is right about not wanting to have the clamp / wedge binder pressing on the USE carbon tube. I ride an Aegis that uses a 26.8 seatpost and has the internal wedge binder. This has made dents in the surface of an Easton carbon seatpost which caused me to have a conversation with both Aegis and Easton. Aegis recommends using a seatpost like USE which has a 25 mm post and uses a metal shim to distribute the load. Easton says their 26.8 seatpost is tough enough to stand the pressure.
re: USE Alien 25 mm carbon seatpost and Look framesetsPaul
Jan 17, 2002 9:50 AM
Jim, Excel doesn't recommend the 25 mm USE for Look frames. Read my other reply to Dave about the clamping. The 386 is a conventional metal clamp. Not sure what the Aegis internal wedge binder really is. Is it a piece of internal metal around the seat post that is clamped by the bolt? After I cut my carbon steerer, I pressed it till the sides almost touched in a vise, and after releasing the vise, the carbon returned to it's original shape, put a spacer over it with no problem. Never did measure the thickness of the Look seat post

If you put a dent in the post, I guess you mean that there is an indentation in the post where the wedge clamped the post. Then you could be losing ridigity in the post, probably why Aegis recommends the USE.

It would be nice if he frame manufacture made this recommendation upon buying the frame, or have a post made to the specification that would work with the clamp. Aegis is a small Maine company if i recall correctly. Look and Colnago C-40 have posts manufactured for their frames. Have to be careful.

Paul
re: USE Alien 25 mm carbon seatpost and Look framesetsJimP
Jan 17, 2002 10:31 AM
Right, Excel recommends NOT using the USE 25mm carbon post. Paul initially mentioned a 27.2 seatpost and I assumed that he knew the correct diameter. That is why I responded about the metal shim. USE carbon posts only come in a couple of diameters and then they sell shims for the rest of the sizes.
The Aegis binder is two aluminum cylinders connected by a screw. The inside edges of the cylinder are cut on a 26.8 mm diameter curve. When the screw is tightened, the wedgelike pieces press against the seatpost from two points and squeeze it against the back of the seattube. This is ahead of the seattube and below the toptube. It is a very clever, lightweight mechanism but can be hard on carbon seatposts. Easton's comment was that the epoxy used to make carbon fibre components is quite soft and will be dented without much pressure. The carbon fiber under the epoxy surface is VERY tough and unless you break the fibers, it isn't hurt.
re: USE Alien 25 mm carbon seatpost and Look framesetsPaul
Jan 17, 2002 10:54 AM
Jim, I did state the seat post for Look was 25mm, but later mentioned 27.2 which was in reference to the other USE size. Sorry, I should have been clearer. Thanks for the iput.

Paul
re: USE Alien 25 mm carbon seatpost and Look framesetsDave Hickey
Jan 17, 2002 8:35 AM
Correct me if I'm wrong but, the LOOK seat tube doesn't actually clamp like most bikes. Most bikes have a round clamp that applies uniform pressure on the seat post. The LOOK mechanism is actually a bolt that applies pressure to the back of the seatpost. That is why Excel doesn't recommend USE. USE's walls are too thin. The LOOK ergo post has alot thicker walls compared to the USE. I'll look tonight when I get home.
386 has a metal clamp, 281 etc., has a bolt in backPaul
Jan 17, 2002 8:46 AM
I thought the same thing, what's the difference between my 386 metal clamp and others that have a metal clamp. It seems the bolt in the back would apply more pressure because it's AL butted. The 386 is compressing carbon against carbon. Colorado Cyclist sells the same post, but with no warning. I can only guess that Excel had returns on the USE due to cracking. One guy mentioned that it has a metal internal shim. Cutting corners to save a few grams doesn't impress me.

Paul
what has a metal shim???? nmCT1
Jan 17, 2002 8:46 PM
Current catalog...Mike Prince
Jan 17, 2002 4:31 PM
Shows a 361 with a USE carbon post. Interesting given their recommendation to not use this post with LOOK frames.
Where?Ian
Jan 18, 2002 8:39 AM
I don't see a KG361 pictured with a seatpost at all. Where is the picture at?
Page 5Mike Prince
Jan 18, 2002 10:26 AM
At the bottom there is a KG361 with an Alien carbon post. It just came in the mail the other day, Excel Sports Cat #59.

Mike
Oh...Ian
Jan 18, 2002 12:06 PM
... I though you meant the Look catalog, my bad.
I have a carbon Alien on my KG281CT1
Jan 17, 2002 8:44 PM
The internal pinch bolt on the LOOK frame does dent the thin carbon tubing of the Alien post. I've been using this combo for a couple of months and have had the seat post slip sideways a couple of times. No big deal but a little anoying.

If you do plan on using this combo I'd suggest an internal sleeve to strengthen the post. I'll do the same when I get time to do it.

YMMV
JohnG
re: USE Alien 25 mm carbon seatpost and Look framesetsJimP
Jan 18, 2002 6:19 AM
I emailed USE last night about future availablity of their carbon aero post in a 25mm size. The reply was that there was no current plan to offer it in that size but.... Since the CSC-Tiscali road team used the USE carbon 25mm round seatpost in their Look frames last season and USE thinks they will be using their seatposts this year, they will probably start making the aero post for them. Guess that it is good enough for the pros... I emailed Excel this morning with this.... I'll post their response.