Seat post sinking ;-(

Jamieg285

The seatpost on my new bike keeps sinking, between 5 and 10mm each time.

There is some form of grease on the post since I got it, what is this there for? I'm assuming that there's a reason for it, but I also think it's that what is allowing the post to slip.

And yes, the clamp is tight!!

nicklouse

the clamp is not tight enough.

and yes there should be some grease or you will find the seat post sized in the frame.

Jamieg285

Fair do's. I'll try tightening it a bit more then. (already done that twice)

Is it possible to go too tight, or break the clamp whilst trying?

ollie_lucas1985

When I had this issue a while ago I was doing it pretty tight, but when I had a mate look at it, it really wasn't tight at all .. Now I have a little trouble undoing it but it doesn't creep down any-more!

.blitz

QR seat clamps often seem tight when they're not. Bolt-up clamps are much better ime

andrewjoseph

try some carbon assembly paste. this is designed for carbon parts to fit without grease and to reduce clamping pressures.

I use it on seatposts and stems (not carbon). My wife likes it as now she can undo seat clamps on her own.

delcol

what seat clamp have you got?

my santacruz heckler used to do this no matter how tight the clamp the post would slide down when riding..

so did my pace rc305 had to do the clamp up super tight to stop it..

i replaced the qr seat clamp with a chromag one it worked on the heckler so i did the same on the pace and it worked no more slipping seatpost and no more having to overtighten the clamp.

Anonymous

First thing is have you got a carbon frame and/or post anyway?

That may explain the grease stuff as it could be carbon paste. Regardless if you've got carbon there the paste will help a lot to prevent slipping.

That aside, as said the paste helps anyway even without carbon, and some manufacturers recommend it now anyway for alloy.

Some stock clamps can seem tight when doing them up. It's the QR lever that's tight usually, not the actual clamping. I've switched to Hope clamps which I find smoother and easier to tighten but still should require a bit of effort to tighten to be sure it won't slip.

It's difficult to break the frame, even with carbon, so long as you have a seat post in there, but carbon paste allows you to use less force without it slipping.

386ka

You can also lube the lever of the seatpost clamp - that way it will be easier to clamp it tighter.

tom_fun

What 386ka says, i had the same issue. I thought my clamp was up really tight as it was hard to close it and even harder to open it but the post still slipped. A dab of grease on the clamp and it is now much easier to open and close the clamp and I can get it tighter with no post slip.