# seat clamp problem



## gormleyflyer2002 (Sep 12, 2005)

i have been testing a few selle SMP seats and have found that the are sliding backwards in the seat clamp. The rails seem like a nice fit in the clamp but ?? wtf

i have cleaned and re tried ..... no luck..........even tried some taxc carbon paste.....still slipping.

any ideas on what i can check or do differently.

thanks


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## zac (Aug 5, 2005)

What seat post are you using? It may be time for a new one.

If different saddles are all sliding then your seat post (really the rail clamp) is probably toast (or may be toast)**.

The saddle clamp really doesn't need to be super tight but it is snug, usually around 15-20 Nm depending on the post and rails. It should hold just fine if the initial install is clean and proper and to torque spec. That being said, the saddle clamp doesn't last forever and maybe yours needs to be replaced. Even a slight deformation can prevent a secure hold, as those rails are pretty small and there is very little surface area contact between clamp finger and rail.

Lastly I wouldn't use carbon paste in this situation. Since the contact points are so small and totally exposed, there really is no need.

**One last thing to check is to measure the rails on your last old saddle that held firmly. They may have been slightly oversized and thus "opened up" the rail clamp fingers. Compare this measurement against the Selle Italia rails.

HTH
zac


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## gormleyflyer2002 (Sep 12, 2005)

thanks Zac

...I should have mentioned it was the newer style 09 5.5 non set back style.


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## zac (Aug 5, 2005)

gormleyflyer2002 said:


> thanks Zac
> 
> ...I should have mentioned it was the newer style 09 5.5 non set back style.



Ok, that helps.

The Seat mast cap both holds the saddle rails and the tilt and yaw of the saddle with one 5mm bolt.

Try this:

1) Unscrew the bolt
2) Remove saddle
3) completely remove the bolt, and other hardware from the seat mast cap. This should include a washer, the two outer rail clamp triangular parts (silver), the two inner cone base parts that fit into the cap (semi circular & black), and a long spring. Pay attention to how it disassembles, especially which side the parts are on. While I am pretty sure it is symmetric and the right/left orientation doesn't matter, I am not 100% sure.
4) clean inside the cap area and the four inner and outer rail clamp parts
5) lightly grease inside the seat mast cap socket where the inner cone rail clamps fit.
6) reassemble the entire system.
7) DO NOT grease the rails or the rail clamp areas.
8) make sure the lower slot on the inner cone rail clamps (black parts) fit within the outer rail clamp slots. This is on the bottom of the triangular part and helps keep everything aligned.
9) Install saddle and tighten the 5mm saddle bolt to 16Nm

Hopefully this should work out for you.

If you still get movement, you may want to shim the saddle rails with a single wrap of scotch tape. It will disintegrate, but the added thickness may be all you need to snug things up.

A torque wrench would also come in handy here too, 15-20Nm is pretty snug, especially if you are using one of those short L shaped hex-allen keys. (by way of reference, the lockring on a Shimano cassette needs 40Nm). If you are using one of those L shaped keys, you may want to get a bigger set of T handled hex wrenches (4, 5, 6 and 8 are most useful).

Also note too, that the torque required for the two seat mast cap bolts themselves are very light in comparison...only ~ 4-6Nm.

HTH
zac


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## gormleyflyer2002 (Sep 12, 2005)

thanks Zac......well after closer inspection I found what I think is the problem. I had striped the allen socket of the original bolt and threw in a standard ss socket head bolt that has deformed the bore and locating face of the silver/triangle bit. Probably enough to cause this. 

thanks...........wonder if Trek sell these parts seperate ?


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## zac (Aug 5, 2005)

gormleyflyer2002 said:


> ....wonder if Trek sell these parts seperate ?


Take a trip by/call some of your local Trek dealers. They may have some caps that are busted up for some reason or another, and may sell you the rail assembly for cheap.

Else you are looking at replacing the entire seat mast cap for $$$.

Good luck
zac


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## nor_cal_rider (Dec 18, 2006)

I have a spare seat mast from my "busticated" '08 5.2 Madone. Let me know if you need it - my replacement is a '10 6 Series and I've been told the seat post is a slightly different shape.


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## gormleyflyer2002 (Sep 12, 2005)

no cal......sent you a PM


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## percy (May 17, 2004)

I recently over-tightened my '09 5.5 seat cap clamp bolt and snapped the bolt. It was a pretty spactacular event ... sounded almost like a gun shot and parts flew all over the place when the spring let go. My wife came running downstairs to see if I was OK. Ironically it was one of the few times I trusted myself and didn't use the torque wrench. Lesson learned. 

Long and short of it was that my LBS had extra hardware in their spare parts box and threw me a new bolt. They had plenty of new-style seatmasts in hand from folks who had switched them out after a new bike purchase or after they'd ridden for awhile and changed it out during a bike fit. Even if they didn't have one in the spare parts bucket they said they could order any of the hardware. So it only becomes a big problem if you somehow damage the actual carbon. 

Whatever you do, don't overtighten the two bolts that secure the cap to the mast!


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