Carbon seat post slipping in aluminium seat tube

Jamey

My seat post keeps slipping down, to the point where the saddle can be as much as an inch lower at the end of a day's commuting.

I'm tightening the seat post clamp as much as I dare but I'm scared of breaking the seat post or stripping the threads if I go any tighter.

The bike is a Specialized Tricross Sport, with an aluminium frame and a carbon seat post. the seat post clamp is not a quick release type, it's just a normal one with a bolt.

I've done a little searching and some people mention a paste made by Tacx but that seems to be for carbon/carbon interfaces and I'm not sure it would work for a carbon/aluminium combination like mine.

salsarider79

You've got a very nice bike, but then I'm after one too.
The Tacx paste is exactly what you need. It can be used on either carbon or alloy frames. Spread a bit liberally around your seatpost reinsert and tighten. I was losing anything upto 3 inches on my tarmac over 30mile rides, then I got some tacx and hey presto, no more slippage. Go to a good bike shop and they should have some. Its not worth buying a whole tub for one application.

lochindaal

Or the specialist website says use some sand paper on the inner part of the tube and then put the seat back in with some talc on it.

I did this and no problem since. Very cheap too.

Slow Downcp

Hairpsray works on carbon/carbon - don't see why it wouldn't work on carbon/alloy

andy_wrx

Tacx will be ideal.

Many 'carbon' frames actually have an alu section bonded inside the top of the seat-tube anyway, so that someone hamfisted doesn't over-tighten the clamp and crush the carbon tube.

You don't have to buy the big pot of the stuff for about a tenner, you can also get a tube for £3-odd
http://www.probikekit.com/display.php?code=A1637

Jamey

andy_wrx wrote:

You don't have to buy the big pot of the stuff for about a tenner, you can also get a tube for £3-odd
http://www.probikekit.com/display.php?code=A1637

Cheers Andy but that place is out of stock. I've found some elsewhere online (my local shops don't have any at the moment), however nobody seems to have the tube/syringe, only the tub.

I'll probably buy it anyway (would rather spend a tenner than damage my bike) but is there anywhere else on the bike I can use it, just to try to get my money's worth a bit more?

Jamey

Ordered the tub.

Max_Man

My Allez Elite, Carbon seat post/Alloy seat tube, slipped all the time when I first got it.

Easy, very cheap fix.....hairspray! Apply liberally to seat post and let dry, refit the post and tighten to spec, sorted.

Jamey

What about years from now when you want to remove the seatpost and you used hairspray? Surely that's a situation when the Tacx paste would be superior?

Slow Downcp

Jamey wrote:

What about years from now when you want to remove the seatpost and you used hairspray? Surely that's a situation when the Tacx paste would be superior?

Not really - it's only hairspray. It will come out easily. It just stops it slipping.

Jamey

Oh well... The paste has been dispatched and it was free delivery so I can't complain. Only a tenner. If anyone is riding through the Croydon area and has a carbon seatpost they want pasting then drop by my place

Back to my earlier question... Will this gunge be any use on other parts of the bike?

Gav2000

I have put a reflector on my seatpost and have butted it up against the top of the seat tube. This helps to stop any slip without any extra additives.

Gav

andy_wrx

Jamey wrote:

Back to my earlier question... Will this gunge be any use on other parts of the bike?

Well, when you start getting keen (= money to burn), you'll have carbon bars, carbon stem, a carbon chainset, bottlecage and brake bolts going into your carbon frame...