Carbon Fibre repair glue to patch a seatpost?

Discuss light weight issues concerning road bikes & parts.
Shrike
Posts: 1133
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

Some mad noise coming from my bike last weekend. Wasn't something that's come on gradually, just last Saturday on certain low gradients, like 1 to 3% this weird metallic screeching noise started. Skreetch, skreetch, skreetch.

Kept stopping and inspection was useless. Figured the noise was possibly related to chainring bolts, kinda sounded like it was coming from there. Last night I undid the whole chainset, cleaned the bottom bracket and everything. Regreased all bolts etc. Took bike out for a few mins, seemed fine.

Took bike out for a quickie now - bloody noise is back. At side of road I notice a crack on the seatpost! It's been slipping really gradually I guess. See pic!

Image
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Initial response was to sue Cervelo to the balls. By time I got home I figured I'd just get some glue or something instead.

What you think of this stuff?
http://www.easycomposites.co.uk/#!/resi ... fibre.html

You guys ever used anything decent to patch a seatpost?

Any tips on stopping this from slipping. It was great for months. Maybe I should clean it every few weeks and redo the Finish Line paste. It does seem good, maybe just needs reapplied occasionally. Torque seemed to work too, using 12nm.

sungod
Posts: 1462
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

12Nm for a seat post!!! mine is 6 max

unless you get the layup and bonding right it may not be a strong repair, seatpost failure could be nasty, personally i'd get a new one

to prevent slippage, i've found a mix of finish line and tacx paste works better than either on its own

by Weenie


Shrike
Posts: 1133
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

Just bought this post back in March! Ain't buying no new nothin' :D If it fails, it fails. Seen guys on track on road ride without seat posts like a boss. I'll go back to plan A and start whining at some customer support guy until I get a replacement if it comes to that :P

Missus' seatpost is 5nm. Should see the state of me winding this thing up to 12nm... nervous wreck.

I'll try some tacx and mix it in. Maybe Amazon has some and the carbon repair glue. Don't have much time left until the weekend!

thebadgerboy1982
Posts: 20
Joined: Mon Sep 21, 2015 6:37 pm

by thebadgerboy1982

i had this exact issue with my s3. i ended up getting a new seatpost from cervelo as well as a new binder.
things cervelo asked me to do:
make sure no carbon paste at the binder/carbon seatpost interface
Torque to 12nm, any less and the post will slip
strip the loctite and grease from the binder bolt as it can affect how much torque you need to put through it to get to 12nm
use a thin layer of carbon assembly paste

hope this helps

kevosinn
in the industry
Posts: 637
Joined: Mon Mar 05, 2012 7:28 am
Contact:

by kevosinn

Putting resin or glue in there will not do a thing. You may as well not do anything. The fiber has been broken and damaged. The only way to properly fix this is to remove the damaged material and repair the area matching fiber orientation.

Edit- leave a repair like that to a professional or get a new post. It's probably cheaper to just get a post. Have you reached out to cervelo? Maybe they could give you a discounted price on one. Just a thought.
Www.crypticcycles.com Custom carbon frames, bar/stem combos, repair and component tuning.

Patto
Posts: 21
Joined: Wed Sep 14, 2016 8:33 pm

by Patto

A round seat post flexes too much for a spot repair to work. You could fix it so it will no longer break, but it will be rigid.

Buy another.

TheKaiser
Posts: 469
Joined: Thu Sep 05, 2013 3:29 pm

by TheKaiser

Patto wrote:A round seat post flexes too much for a spot repair to work. You could fix it so it will no longer break, but it will be rigid.

Buy another.


Agreed that buying another (or getting a free warranty one) is probably the best choice, but this post isn't round based on his 3rd picture down. It has an aero teardrop cross section, which will reduce flex quite a bit.

totalcompactroad
Posts: 32
Joined: Tue Jan 31, 2017 11:12 pm

by totalcompactroad

Was the seatpost bought new? if so might as well try the warranty route first of all and see what they say

Patto
Posts: 21
Joined: Wed Sep 14, 2016 8:33 pm

by Patto

TheKaiser wrote:
Patto wrote:A round seat post flexes too much for a spot repair to work. You could fix it so it will no longer break, but it will be rigid.

Buy another.


Agreed that buying another (or getting a free warranty one) is probably the best choice, but this post isn't round based on his 3rd picture down. It has an aero teardrop cross section, which will reduce flex quite a bit.


Missed that one. :)

In that case, go to town. Arildite or nearly any 30min + curing epoxy without fillers will do. Preparation and repair technique is more important than glue selection in this case.

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BRM
Posts: 817
Joined: Sun Mar 16, 2014 3:43 pm

by BRM

Fiddling with epoxy will void your warranty

As kevosinn already mentioned, in this case fiddling with epoxy will not be succesful anyway

joejack951
Posts: 323
Joined: Fri Feb 18, 2005 6:50 pm
Location: Wilmington, DE

by joejack951

Maybe try filling it with an expanding foam? If it was round, it would be fairly easy to insert a metal sleeve but the aero profile will make that quite a challenge. At this point, the seatpost is either trash or possibly salvageable so you don't have anything to lose, other than money and time!

kode54
Posts: 1125
Joined: Tue May 23, 2006 9:39 pm

by kode54

if you don't repair it or buy a new one...you'll eventually ruin your seat tube on your frame. cheaper to replace seat post.

there are places that can repair that seat post...but i wouldn't ride on that until you do something about it.
- AX Lightness Vial EVO D + DA9150 + Enve SES 3.4 carbon hubs
- Parlee Altum + DA9150 + Enve SES 4.5 carbon hubs
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- Independent Fabrication Ti FLW + DA9100 + Enve 3.4 CK hubs

Shrike
Posts: 1133
Joined: Fri Jun 03, 2016 5:08 pm

by Shrike

Thank guys, I've messaged Cervelo support, hoping they'll reply before I decide what to do next. (Messaged them last week). Bought epoxy, but holding out for now. Maybe fire off for a quote from one of the carbon repair places. New post is £130, carbon repair might cost as much I'm guessing for a small job. :shock:

sungod
Posts: 1462
Joined: Fri Dec 24, 2010 9:37 pm
Location: it's raining, it must be uk

by sungod

if the cracked area is above the top of the seat tube, you could wrap it externally with cf, won't be pretty but it should be much stronger than simply putting epoxy into an area where it looks like the material has failed, you can get a cf repair kit for about 30 quid

i may be mistaken, but from the image it looks like there's bare cf showing there, as if it the resin didn't get to it during manufacture

wingguy
Posts: 3666
Joined: Thu Mar 08, 2012 11:43 pm

by wingguy

Shrike wrote:Initial response was to sue Cervelo to the balls.....

...Torque seemed to work too, using 12nm.

:roll: :roll: :roll:

Kids these days :lol:

sungod wrote:if the cracked area is above the top of the seat tube

It's not above the top of the seattube, it's where the wedge clamp has crushed the carbon through overtightening.

by Weenie


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