carbon aero seat post cracked :(

chatlow

I'm so annoyed.. Just found a crack on my Giant Tcr advanced and has covered less than 100 miles.

Can this be fixed? Crack doesn't feel too deep. Bought the bike second hand so can't claim warranty I don't think..

chatlow

Crack doesn't feel all that deep but still worried

sungod

you can probably get the seat tube repaired ok as some layers of cf can be externally applied, may need some ingenuity to adapt/replace the clamp

i'd think the post itself would be hard to repair, external cf would prevent it being inserted in the seat tube, so you probably need a new one

if you used a credit/charge card, does it include any purchase protection? it's often no use, but worth a check

someone else has a similar issue, some more advice comment here...

viewtopic.php?f=40004&t=12972497

dilatory

sungod wrote:

http://www.bikeradar.com/forums/viewtopic.php?f=40004&t=12972497

That chap has a crack in his seat tube.

This chap seems to just have cracked his seat post?

Are you sure the crack wasn't there when you bought it and has just gotten worse? I suppose at least a new seatpost is cheaper than the result of a cracked seat tube!

chatlow

Thanks for the link. The crack on the seat tube literally goes all the way around and is just underneath the clamp. Haven't had a chance to see how bad it is. I am watching a replacement aero seat post on eBay which is alloy and may be better. Any idea how much carbon repairs are?

sungod

dilatory wrote:

sungod wrote:

http://www.bikeradar.com/forums/viewtopic.php?f=40004&t=12972497

That chap has a crack in his seat tube.

This chap seems to just have cracked his seat post?

Are you sure the crack wasn't there when you bought it and has just gotten worse? I suppose at least a new seatpost is cheaper than the result of a cracked seat tube!

er, enable read mode
read viewtopic.php?f=40004&t=12972581#p18915983
etc.

sungod

chatlow wrote:

Thanks for the link. The crack on the seat tube literally goes all the way around and is just underneath the clamp. Haven't had a chance to see how bad it is. I am watching a replacement aero seat post on eBay which is alloy and may be better. Any idea how much carbon repairs are?

really the only way to be sure is contact a cf repairer with info and (good) pics and ask for an estimate

dilatory

Ah, my bad. I lose at forums.

tuneskyline

chatlow wrote:

Thanks for the link. The crack on the seat tube literally goes all the way around and is just underneath the clamp. Haven't had a chance to see how bad it is. I am watching a replacement aero seat post on eBay which is alloy and may be better. Any idea how much carbon repairs are?

Do not put an alloy seat post in a carbon frame. Galvanic corrosion. You have just been unlucky or it was over tightened.

chatlow

Ok the crack going around the seat tube is external only, I'm not seeing anything on the inside. Maybe just paint, but will get lbs to confirm this.

sandyballs

If you need a new seat post Pedal On got me one, great fast service.

chatlow

tuneskyline wrote:

chatlow wrote:

Thanks for the link. The crack on the seat tube literally goes all the way around and is just underneath the clamp. Haven't had a chance to see how bad it is. I am watching a replacement aero seat post on eBay which is alloy and may be better. Any idea how much carbon repairs are?

Do not put an alloy seat post in a carbon frame. Galvanic corrosion. You have just been unlucky or it was over tightened.

Is this a definite no no? Google saying about corrosion but a lot haven't had problems.

sungod

isn't the seatpost cf too? looked like it from the pic

but you can use alloy with cf, though if there's any wet riding it's advisable to check for corrosion every few months, and use some assembly paste (essentially it's a grease with grippy particles in it) to reduce the chances of corrosion and also lessen required clamping force

best to also use assembly paste on cf-cf to lessen clamping force, the pink tacx stuff is quite smooth, the clear finish line one is much grittier

i use a bit of both on my seat post (85g of weightweenie cf post into stainless steel) to reduce clamping force, i found the combination gives more grip than either on its own

Matthewfalle

tuneskyline wrote:

chatlow wrote:

Thanks for the link. The crack on the seat tube literally goes all the way around and is just underneath the clamp. Haven't had a chance to see how bad it is. I am watching a replacement aero seat post on eBay which is alloy and may be better. Any idea how much carbon repairs are?

Do not put an alloy seat post in a carbon frame. Galvanic corrosion. You have just been unlucky or it was over tightened.

Baloney. Utter baloney. Just slap some copper slip/carbon paste in there and it'll be fine.

Exactly the same principle as running a carbon seat post in an Ali frame.

At worst, remove every 6 months, clean, re-copperslip or paste and put back in.

chatlow

Awesome, thanks guys. Will keep an eye on the clamp connection every few months.

tuneskyline

Matthewfalle wrote:

tuneskyline wrote:

chatlow wrote:

Thanks for the link. The crack on the seat tube literally goes all the way around and is just underneath the clamp. Haven't had a chance to see how bad it is. I am watching a replacement aero seat post on eBay which is alloy and may be better. Any idea how much carbon repairs are?

Do not put an alloy seat post in a carbon frame. Galvanic corrosion. You have just been unlucky or it was over tightened.

Baloney. Utter baloney. Just slap some copper slip/carbon paste in there and it'll be fine.

Exactly the same principle as running a carbon seat post in an Ali frame.

At worst, remove every 6 months, clean, re-copperslip or paste and put back in.

No It's not baloney. Galvanic corrosion can spread quite fast especially in damp/humid/salty conditions. It has ruined many a frame. I understand the point you are making but I had a frame that had severe damage to it after only 2 months. I now only have Carbon or Titanium contact points on my carbon frames due to first hand experience of Galvanic corrosion. Alloy and carbon are not a good mix.

rolf_f

tuneskyline wrote:

No It's not baloney. Galvanic corrosion can spread quite fast especially in damp/humid/salty conditions. It has ruined many a frame. I understand the point you are making but I had a frame that had severe damage to it after only 2 months. I now only have Carbon or Titanium contact points on my carbon frames due to first hand experience of Galvanic corrosion. Alloy and carbon are not a good mix.

My Ribbles carbon fork with alloy steerer is still largely mint after 21000 miles in all weathers. My Deda carbon handlebars are matched with an alloy stem (they don't even make a carbon stem for those bars).

Matthewfalle

Its only an issue if you neglect it - ie stick it in dry (ooeerrr) and leave it forever.

It will happen with any two materials; how many threads do you see on here saying "stuck seat post".

Its not a real issue if you aren't a masher so need to try and freak someone out over it.

Sorry, but baloney that its a big "do not".

chatlow

new replacement on its way to me. Will fit it with copper paste applied around the bit where it clamps. I have read that you should have the clamp tighten opposite the slot opening? From what I can see with the tcr advanced, this is impossible, as the clamp can only go on one way and the pinch bolts are directly over the slot, which has caused paint cracking on the frame seat post. is it worth getting a different clamp or will it be ok?

also will it be the same torque setting - 5nm?

thanks

sungod

i'd use carbon assembly compound rather than metal-loaded anti-seize

for instance... www.wiggle.co.uk/tacx-carbon-assembly-compound-80g

it's a grease so it'll prevent corrosion, but it'll also reduce the clamping force needed

clean the inside of the seat tube (wad of cloth on skillfully bent wire coat hanger) before fitting the new post

apply a thin layer of assembly compound over the full inserted length of the post, excess will squish out as you slide the post in

only tighten the clamp enough to prevent any slippage, try 4Nm, if not enough try 0.5 increments until it's secure

keef66

I have 2 bikes; one's a carbon frame with an alloy seatpost, the other's an alu frame with a carbon post. On both I use a thin smear of carbon assembly paste so the post doesn't slip and I don't have to tighten the clamp very much. I probably remove them once a year for a wipe and reapplication. No sign of any corrosion on either.

chatlow

Thanks all for the reassurance. The new post arrived today and got some carbon compound on its way. The thin crack around the tube looks like paint only as can't see anything on the inside.

sungod

contact a professional cf repairer, get a quote

judging from the photo, if that's the only issue i'd think they'll be able to wrap the tube and save it

for instance...

http://carbonfibrerepair.com/repair-process/

there are others

mitchgixer6

Judging by the cracks on both seat post and frame it looks like it's been over tightened. Once you get it fixed I'd invest in a torque wrench.