/ Carbon seat tube crack, possible shop negligence?

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gethin_allen on 02 Sep 2014
This is a complicated one but I'd be grateful if you stay with me.

I got a Giant TCR3 bike through a cycle to work scheme and then had a few issues with it. The supplier (that was specified by my work place so not my choice) said, that's fine take it to your LBS and if it needs paying for they'd foot the bill.

So I took it to my LBS and mechanic there messed about with it and semi sorted the problem I went there for, THEN, he asked if I'd had the seatpost trimmed at an angle as this was now Giant spec to prevent and chances of damaging the frame if the seatpost is rammed right down for some reason. He said he'd sort it out for me, I said fine that's great. He then made the most wonky cut possible across the seat post (it's aero so wouldn't go in the guide and then put everything back together. They didn't charge me for this so I thought great.

All was well I thought until today when I changed the saddle and consequently needed to move the seatpost. This was when I found a crack in the frame just below the seat clamp where it seems it was over tightened
( https://www.flickr.com/photos/44546121@N04/15121089102/ ).
The threads on the seatpost clamp also appear damaged.

Any idea how to proceed with this and if I have any leg to stand on as I have no proof of anything and they could just deny everything.

Obviously I haven't had a chance to speak to the shop about it as it's late but I'm now massively stressing about it.
Rigid Raider - on 03 Sep 2014
In reply to gethin_allen:
It looks as if the crack has a start and a finish and so might not spread - or am I wrong? It's hard to tell. As you've already guessed, the shop is not going to admit to the damage so you're going to be left with it. I would buy a new clamp and a torque wrench, torque it up to the correct setting and carry on riding, while keeping an eye on it.
Post edited at 09:07
gethin_allen on 03 Sep 2014
In reply to Rigid Raider:

It runs from the cut out to allow some flex for tightening to the seat post, I've no idea how racks spread in carbon fibre but they must do somehow. The aforementioned cut out actually looks quite short compared to other frames I've looked at and quite badly finished suggesting there is a stress concentration. I'm going to speak to a friend of a friend who works with carbon in aerospace applications and see what he suggests.
mark catcher - on 03 Sep 2014
In reply to gethin_allen: Looks like being the LBS at fault, however have you ever hung it up by it's saddle? Doing this has been known to put unusual stress on the rear of the post. I'd be stressed too...tragic.

gethin_allen on 03 Sep 2014
In reply to mark catcher:

" have you ever hung it up by it's saddle? Doing this has been known to put unusual stress on the rear of the post."

I haven't but I would be surprised if that could cause much stress in anything as the bike weighs next to nothing compared to me bouncing around on top of it.


TimB - on 03 Sep 2014
In reply to gethin_allen:

Maybe it's just your photo, but the shadow at the left hand side of the crack makes it look like there's an odd fold in the carbon frame itself (emphasised by the interrupted dirt line just below the clamp).

If the frame has cracked there due to a manufacturing fault then it might be possible to get a warranty replacement.
Siward on 03 Sep 2014
In reply to gethin_allen:
First step has got to be to speak with the shop.

If its the sort of shop that relies on its reputation, i.e. it's a decent, proper LBS then you may be pleasantly surprised by their reaction.

If they're a bunch of fly by night shysters then obviously they will deny any responsibility.

But it has to be worth a go hasn't it? How sure are you it was down to them?
Post edited at 14:21
Timmd on 03 Sep 2014
In reply to gethin_allen:
My gut tells me to suggest going and grumbling to Giant about what's happened to your frame and asking nicely if they can do anything, just because they're a very big brand and might either give you a frame or talk to your bike shop and sort something out.

You might be lucky with your bike shop though.

There are people who do repairs to carbon fibre bike frames, it's hopefully not a place which could lead to increased stresses somewhere else in the frame if it was repaired in a way which isn't an exact match to how it was manufactured.

A frame tube join could be more of a concern, but you'll likely be okay having that repaired, and it mightn't cost a lot too.

You shouldn't have to pay, but if it comes to it...
Post edited at 16:47
gethin_allen on 03 Sep 2014
In reply to gethin_allen:

I'll head back to the shop tomorrow, I would go today but they close by 6.

I can't think of any other time when I adjusted the seat post since i took it in (although it has been a while) so there must be some connection between the shop and the crack.

Looking more closely, the seat post also appears slightly squashed.

In general the whole design seems a bit flawed. If I don't get any result with the shop I'll try Giant and if not then I may try a repair, but a repair would be difficult with the seat post on the one side and the clamp on the other not leaving anywhere to build up carbon sheeting.
gethin_allen on 04 Sep 2014
In reply to gethin_allen:

Went to the shop on the way home (on my other bike) just to discuss things and show them photos as I didn't have time to go home and get the car and broken bike.

And just to make me feel better I fell off my bike due to mud on the path and now have another slightly broken bike and a bruise the size of a grapefruit on my arse. Great.
danm - on 04 Sep 2014
In reply to gethin_allen:

Before you left the bike with the LBS, had you had a good look at the areas which are now damaged? If not, the frame could have been damaged previously and you might get a replacement from Giant. How long have you had it?
gethin_allen on 04 Sep 2014
In reply to danm:

I hadn't noticed anything wrong with the frame before it went to the shop, but I hadn't looked closely.
I got the bike on the 19th of March so just under 6 months. The shop reckons that a frame shouldn't crack like this even if the clamp was over tightened so this sounds positive.
Rigid Raider - on 05 Sep 2014
In reply to gethin_allen:

A carbon seat post is a pretty rigid structure and difficult to compress to the extent that that tab of material would actually snap. If the seatpost was too small for the frame tube, it might be possible.

When you get sorted, it's worth buying a small torque wrench for jobs like that. Once you've torqued the clamp up to the manufacturer's figure, undo it by hand with a standard hex key and you'll be amazed at how tight it is.
Toby_W on 05 Sep 2014
In reply to Rigid Raider:

Agree with RR torque wrench and carbon grease and remember the torque value is a maximum. My seatpost is 4.5 and I tighten to 3.

I agree with the other statement above it would be very hard to damage the frame without crushing the seatpost. I have seen 3 bikes with failure at that point, two specialized that were swopped straight away and a felt (don't know what the out come was for that but I could find out if you want).
Good luck with it all, it's a sh***y thing to happen whatever the reason.

cheers

Toby
gethin_allen on 05 Sep 2014
In reply to Toby_W:
I do actually have a torque wrench which is one of the reasons I don't think it was me that would have over tightened it. I tightened it to 5 nm as is states on the clamp itself.
Toby_W on 05 Sep 2014
In reply to gethin_allen:

Not meaning to teach you to suck eggs :-)

Toby
gethin_allen on 05 Sep 2014
In reply to Toby_W:

No offence taken. I only bought the torque wrench because I was paranoid about buggering up this bike. All the contact points on my other bikes are steel or alu so carbon was a leap into the unknown for me.
Rigid Raider - on 05 Sep 2014
In reply to gethin_allen:

Then possibly the carbon mat didn't extend sufficiently to that area? Unlikely I suppose because I guess they make the frame tube longer then saw it off.
gethin_allen on 05 Sep 2014
In reply to Rigid Raider:

I took it back to the shop and they are assessing it so fingers crossed something will get sorted.

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