# Seat slipping back.....and back.....



## twelve34 (Apr 4, 2010)

I have a new bike and the seat keeps slipping back. I set the bike up with the front of my knee basically centered over the stem of the pedal. It has slowly gone back about .5 cm.

I checked my mountain bike setup, which I think is perfect, and my knee is a little behind the center of the stem.

I live where there a several hills and every ride ends with a fairly steep ride that climbs 500 feet. 

When I first started riding, it slipped more, and I put some of the carbon paste you use to make parts grip; though the saddle rail is the K:ium stuff Fizik uses and the grabbing part of the seat stem is aluminum. It helped. I do not want to clamp the seat down any harder, it is already pretty tight--and that part of the stem is carbon.

Two questions:

1. Is this telling me that my body wants the seat further back than I am setting it up? I read that some people who climb alot prefer the saddle back 1-2 cm further than center.

2. If it keeps moving, do I need to use another paste, one that is not for carbon, but aluminum?

Any thoughts or advice is appreciated. The bike is a 2011 BH G5; I am not crazy about the way their seatpost attaches to the saddle (but I love the bike).


Thanks......jim


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## rbart4506 (Aug 4, 2004)

It's telling you that the seat post clamp is either not tight enough or is just plain not good...

Had that issue on my Blue AC1 and once I got the frame warrantied (for another reason) I sold it. The AC1 used a proprietary aero seat post so I had no options to correct the issue. The design of the clamp head, top of seat post and clamp material all contributed to the clamp being prone to deforming, which allowed the saddle to slip. Once the deformation of the clamp started you were screwed. I had on post warrantied and made sure to properly torque the new one and I had the same issue.

All my other bikes have Thomson Elite seat posts and there is never any saddle slip...

Once you set it, it should not move!


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## fastmb (Oct 5, 2008)

try the fsa carbon assembly paste to keep things from slipping. as for the position that should be decided between you and your fitter.


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## LC (Jan 28, 2004)

Remove the clamp bolts and put some grease on the threads of the bolts, Tighten the bolts harder then before.


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## maxxevv (Jan 18, 2009)

If your clamps are aluminium, take them out, take a 200 or 400 grade sandpaper and scour the surface where they clamp onto the rail. Make sure you smooth our any sharp edges in the process. Clean off any particles and re-clamp on the saddle it will work better.


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## kbwh (May 28, 2010)

And use the appropriate torque for your clamp bolt(s).

Anecdotal: My Campagnolo Record post has an Al lower and composite upper clamp half, and the single bolt shall be torqued to 20-22 Nm. It would not hold the steel rails on my Selle SMP at 20 Nm, but at 22 Nm everything is fine.


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## twinkles (Apr 23, 2007)

Valve grinding compound is available at an auto parts store for $4 a tube. It's got some grit in it and will stop your saddle or seatpost from slipping. I've used with existing grease in the seat tube and by its self on saddle rails. It's worked lika a charm every time I've had a slipping post or saddle.


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## uncrx2003 (Jul 17, 2010)

I had the same problem on my BMC streampost. Read the manual, recommended 7 Nm. Didn't have a torque wrench so I took it to the shop. No problem ever since.


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## spectre-73 (Nov 10, 2008)

Is the seat post a single bolt type like on the G2? I posted my technique to fix the G2 problem under the G4 reviews. Sometimes you can also over tighten seat post clamps and bend the arms down. I did this with a FSA seatpost so I used shim material under the rails to get it to clamp up again.


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