Pitting on carbon seatpost

Jmuzz
Posts: 567
Joined: Mon Jan 29, 2018 1:42 pm

Pitting on carbon seatpost

Postby Jmuzz » Sat Jun 23, 2018 10:31 pm

Giant TCR, carbon seatpost carbon frame.

Took seatpost out for the first time to check what it looked like and trying to find a cracking sound.
Lots of pitting damage chewed into the surface, gritty stuff all over it which I assume is the carbon anti slip compound, seemed like a lot of it.

Is this normal damage on the seatpost after 3 months or has the shop screwed something up?
That post is wrecked cosmetically if anyone ever wants to raise it 1cm and some structural weakening.

Good chance that is the cracking/bang on bumps looking at it, seems like a lot has been moving. It was happening out of saddle too so I had assumed not seat related, though I guess the frame flexes and may have been surfaces moving even when out of seat.

Note is shiny in picture because I put grease on it for refitting.

Image

Thumbnails.

Image

Image

Image

User avatar
OnTrackZeD
Posts: 151
Joined: Sat Aug 03, 2013 12:35 pm

Re: Pitting on carbon seatpost

Postby OnTrackZeD » Sun Jun 24, 2018 5:01 pm

Jmuzz wrote:
Is this normal damage



I am no expert but that looks wrong.

uart
Posts: 1585
Joined: Sat Jan 02, 2016 9:15 pm
Location: Newcastle

Re: Pitting on carbon seatpost

Postby uart » Sun Jun 24, 2018 5:31 pm

Yeah also no expert, but it almost looks like whatever muck they have applied has reacted with the resin and eaten away at it.

User avatar
Duck!
Expert
Posts: 7095
Joined: Tue May 21, 2013 8:21 pm
Location: On The Tools

Re: Pitting on carbon seatpost

Postby Duck! » Sun Jun 24, 2018 8:12 pm

It's only the surface coat, not structural.
I had a thought, but it got run over as it crossed my mind.

HenryCharlie
Posts: 93
Joined: Tue Jan 12, 2016 4:40 pm
Location: Reservoir

Re: Pitting on carbon seatpost

Postby HenryCharlie » Mon Jun 25, 2018 1:01 pm

I'm no expert but I thought putting grease on a carbon seatpost was a big no no.
I overtook some people going uphill once.

Jmuzz
Posts: 567
Joined: Mon Jan 29, 2018 1:42 pm

Re: Pitting on carbon seatpost

Postby Jmuzz » Mon Jun 25, 2018 1:22 pm

As many seem to say Yes as No.
And whatever gritty paste the shop has used has done more harm than anything could.
So should be fine while I work out what has gone wrong.

User avatar
AUbicycles
Site Admin
Site Admin
Posts: 13294
Joined: Tue Aug 23, 2005 2:14 am
Location: Sydney & Frankfurt
Contact:

Re: Pitting on carbon seatpost

Postby AUbicycles » Tue Jun 26, 2018 1:42 am

I have a Giant TCR as well and also use carbon paste so have the usual scuffing and wear though not what I would call pitting.

There is a lot more happening on the surface of yours.. perhaps a different or thicker laquer. Main thing is that the seatpost is structurally sound. I would clean the post and inside of the frame then use a light coating of carbon fibre paste.

Jmuzz
Posts: 567
Joined: Mon Jan 29, 2018 1:42 pm

Re: Pitting on carbon seatpost

Postby Jmuzz » Tue Jun 26, 2018 11:22 am

The good news is that it was indeed the seatpost interface making the cracking sound. That's completely gone.

My grease is a fail, it slipped 5mm in 20km.
So will have to get some proper stuff.

The stuff on there was all dry and gritty, no greasyness to it at all.
I'm thinking it might have been reacting and binding the epoxys and then letting out a crack when the frame had a big flex (would do it even out of saddle) and the pitting may be little chunks ripping out?

I will be taking it to the shop anyway.

User avatar
AUbicycles
Site Admin
Site Admin
Posts: 13294
Joined: Tue Aug 23, 2005 2:14 am
Location: Sydney & Frankfurt
Contact:

Re: Pitting on carbon seatpost

Postby AUbicycles » Wed Jun 27, 2018 7:13 am

The carbon paste is not greasy at all... it is gritty and the binding material is just that.

A good trick is to get a friend or even a willing shop to put a small amount in a ziplock bag. Typically the carbon paste comes in tubs that take decades or probably centuries to get through if you are just doing your own bike every so often. A small amount can last for a couple of applications.... which is many many years.

Who is online

Users browsing this forum: oxonabike