Plainsman

Hi! I’m trying to find a good assembly option for a carbon seat post in an aluminum frame that won’t scratch the carbon post. I have pretty immediate access to the following, but open to other options:

Finish Line Fiber Grip
Motorex Carbon Grease
Park Tool SAC-2
Muc Off Carbon Gripper

is one of these better than the others in terms of holding strength, protecting the carbon from bonding to aluminum, and not harming the carbon finish?

Thanks in advance!

Crankycrank

I think any CF paste will likely leave minor dulling at the least. Any of those above will have little to no difference in corrosion protection or scratching between them. Any scratching/dulling can usually be buffed out with most plastic/paint polishes though if you decide to raise your post at some point. You can always just use grease first and go to the paste if you have slipping.

dsbrantjr

I make all of my controls "race tight", tight enough to stay put under normal stresses, but still able to move/rotate during a spill/crash, hopefully minimizing damage and injuries.

SoSmellyAir

I used Finish Line Fiber Grip to install my matte finish CF seat post (Cannondale Save) a few years ago. A couple of weeks ago I decided to raise it by a quarter inch, and first removed it to wipe off as much of the residue as possible. The Finish Line Fiber Grip did not affect the finish of the seat post. But the seat tube is also CF and the hidden seat post clamp within it is either CF or plastic. No aluminum interface.

Sy Reene

+1 this
I use the SAC2 park stuff because that's what I happened to buy a few years ago. No avoiding marring to some extent -- I have a CF post in a Ti frame, but same idea. Also use this stuff on stem/handlebar clamp interface.

Suggest though you figure out your seatpost height before doing any CF paste. Then do a few wraps of eg. electrical tape or somesuch at that point on the seatpost. This will at least prevent going too far and then having to back in/out of the seat tube while you get it right (which in itself can and will cause marring).

KerryIrons

CF paste is basically grease with grit in it. You only need it if things slip with normal grease and proper torque. Don't overthink this.

Camilo

FWIW, to address the OP's concern about dulling the finish of a CF seatpost. Dulling and superficial scratches can easily be removed and original shine restored with normal polishing products. I have a couple strengths of rubbing compound and normal car polish. Just rub out the scratches and polish. All can be done by hand in about 5 minutes.

Sy Reene

How does that work? I thought CF's natural state is a very matte appearance. If the clear coat gloss finish is scratched (off) will a polish restore areas to gloss?

Camilo

Probably yes, if the clear coat is totally rubbed off. Usually, like a car, it's just dulled and/or often just superficially scratched, not removed. I guess all I can say with certainty is that I've shined up a few carbon fiber seat posts, at least the parts that show above the seat tube and sometimes the entire post. The result might not be "factory fresh" but easily passes the "3 foot" (1 meter) test - looks great from normal viewing distance.