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Seat Post Lube
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
Do you need any special lube for an aluminium seat post into a carbon frame or is normal grease ok?
Cheers
Brian
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I'd imagine normal grease would do.
Or you could try something like Ritchey Liquid Torque if you want to be fancy. I'm actually going to give some of that a go on the next build.
I would have thought that you would use graphite grease
Liquid Torque is the go. I almost stripped the head of my seatpost clamp bolt on the hardtail trying unsuccessfully to stop it slipping - Alloy frame witha carbon post. 'Twill be much the same with an alloy post in a carbon frame.
Actually, scratch that - it wll be worse. Without the grease having the little beads in it, you are likely to overtorque the clamp and crack your frame.
A torque wrench is a good idea - available at good prices from CRC. I've just bought the PRO unit with the tips inlcuded, does 2-15Nm. $130-odd.
If the post slips in the tube at low/normal tightening forces then either the post is too weak or the post/tube diameters don't match. Pikey had the opposite where the tube ID was on bottom tolerance, and the post was on top tolerance. In his case the post almost ended up the chufty.
Lube for a carbon-aluminium seatpost interface is not essential as long as the top coat on the carbon isn't damaged, and the post interface isn't left muddy or wet. How many carbon frames have you seen on eBay that are going cheap because the post is siezed (corroded) into the seat tube? Dozens?
Sure liquid torque et al. do the job, but taking the time to pull the seatpost and dry the tubes when you wash your bike is the best insurance. I'd cry if I went to drop my seatpost and found I had inadvertantly caused my frame to have fixed geometry!
If your new frame and seatpost don't seem happy together take the time to visit your LBS, have them both measured and maybe spend on a new seatpost or go down one size and have a custom shim fitted. If the seat tube is undersized you can always have it reamed by a good shop.
Just think, if the clamp needs to take up a lot of clearance, it is only clamping a narrow ring at the top of the seat tube. The bottom of your seat post is swinging around in the tube and you get creaks and groans. Then you lube the joint to prevent the noises which are caused by a bad fit. Lube just masks the noise, and assists in the clamp interface grinding away at the post...... a neverending downward spiral.
My 2PSI
I run a Carbon seatpost in my carbon Rush. It slipped and nothing could be done to stop it. No amount of cleaning or preparation. I grabbed some Liquid torque and it hasn't moved since. Not only does it stop it from slipping, but it stops it from seizing as well. You only need the slightest smear on it. It does dull the carbon seatpost quite badly, but it's only where it goes into the frame.
Before I had my carbon seatpost, I had an alloy post. It didn't move at all at recommended torque. So it's not a size issue, simply a carbon on carbon issue.
I highly recommend the ritchey torque paste.