Hmm small crack in chain stay ...

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Hmm small crack in chain stay ...

Postby find_bruce » Thu Apr 26, 2012 1:36 pm

Saw a small crack in the seat stay of my 3 month old bike. Closer inspection revealed it to be not quite so small
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So its back to the retailer for me.
Last edited by find_bruce on Thu Apr 26, 2012 8:44 pm, edited 1 time in total.
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by BNA » Thu Apr 26, 2012 2:13 pm

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Re: Hmm small crack in seat stay ...

Postby Nobody » Thu Apr 26, 2012 2:13 pm

Thanks for posting.

Please edumacate us. :)

What brand & model?
How much do you weigh?
Do you ride it on or off road?

Thanks in advance.
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Hmm small crack in seat stay ...

Postby gabrielle260 » Thu Apr 26, 2012 2:17 pm

What's the hole in the second photo?
The reason I ask is that it looks like the crack started there.
I have cracked several frames, most recently a Lynskey, so I know how frustrating/annoying it makes you feel!
Andrew
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Re: Hmm small crack in seat stay ...

Postby find_bruce » Thu Apr 26, 2012 2:52 pm

Nobody wrote:Thanks for posting.

Please edumacate us. :)

What brand & model?
How much do you weigh?
Do you ride it on or off road?

Thanks in advance.

Cell SS101 - alloy frame. I should also have said that it is the drive side seat stay & the hole in the first photo is of the bike upside down.
95 kg

It's my commuter - bike paths and roads, some of which are a bit rough but no off road as such.

gabrielle260 wrote:What's the hole in the second photo?
The reason I ask is that it looks like the crack started there.
I have cracked several frames, most recently a Lynskey, so I know how frustrating/annoying it makes you feel!
Andrew

My guess is that the hole could be intended to drain any water as it is much bigger than the pinholes used to release the welding gasses & it doesn't appear to serve any other useful purpose.

You may be right about the source the crack, as that would explain why the crack did not follow the weld evident in photo 2

My theory though is that the welding evident in photo 1 was of poor quality and failed causing the hole - the crack has then propagated in both directions
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Re: Hmm small crack in seat stay ...

Postby rustychisel » Thu Apr 26, 2012 4:29 pm

from the discolouration etc it looks to have started at that big snot of a weld (photo 1) and propogated. Too hot weld point undercut the tube creating weak point = poor quality frame?*

*mostly guesswork
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Re: Hmm small crack in seat stay ...

Postby rkelsen » Thu Apr 26, 2012 4:50 pm

Not a good look for Cell. Particularly after this:

http://www.bicycles.net.au/forums/viewtopic.php?f=12&t=50539&p=769861
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Re: Hmm small crack in seat stay ...

Postby ozdavo » Thu Apr 26, 2012 5:23 pm

find_bruce wrote: I should also have said that it is the drive side seat stay

Looking at the dropout in the 1st pic, looks like the chain stay to me FWIW
Always looking for new rides & ride partners in SE QLD area
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Re: Hmm small crack in seat stay ...

Postby rustychisel » Thu Apr 26, 2012 5:47 pm

ozdavo wrote:
find_bruce wrote: I should also have said that it is the drive side seat stay

Looking at the dropout in the 1st pic, looks like the chain stay to me FWIW



Good spot. That's the underside of the chainstay (drive side, rear)
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Re: Hmm small crack in seat stay ...

Postby il padrone » Thu Apr 26, 2012 6:53 pm

The hole under the chainstay looks like it was never meant to be there..... ugly welding! Smacks of a "she'll be right" attitude to welding quality control.

Makes me glad my Thorn frame has had all the breather holes brazed up to completely seal the frame tubes :)
Riding bikes in traffic - what seems dangerous is usually safe; what seems safe is often more dangerous.
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Re: Hmm small crack in seat stay ...

Postby find_bruce » Thu Apr 26, 2012 8:46 pm

ozdavo wrote:Looking at the dropout in the 1st pic, looks like the chain stay to me FWIW
Yes you are right, thanks
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Re: Hmm small crack in seat stay ...

Postby Nobody » Thu Apr 26, 2012 9:55 pm

il padrone wrote:Makes me glad my Thorn frame has had all the breather holes brazed up to completely seal the frame tubes :)
Did the factory do this?
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Re: Hmm small crack in seat stay ...

Postby il padrone » Thu Apr 26, 2012 11:37 pm

Nobody wrote:
il padrone wrote:Makes me glad my Thorn frame has had all the breather holes brazed up to completely seal the frame tubes :)
Did the factory do this?

Yes, on the Thorn Nomad Mk2 frames, they're "handbuilt in Taiwan" and the factory does a range of special things - sealed frame breathers, SS drop-outs, SS gear and brake cable guides, 6mm rack mounts for strength - that Thorn specify.
Riding bikes in traffic - what seems dangerous is usually safe; what seems safe is often more dangerous.
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Re: Hmm small crack in chain stay ...

Postby jasonc » Fri Apr 27, 2012 8:00 am

I don't think the word small should be in this thread at all.
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Re: Hmm small crack in chain stay ...

Postby find_bruce » Fri Apr 27, 2012 9:44 am

jasonc wrote:I don't think the word small should be in this thread at all.

It was only a very narrow crack - barely perceptable from above. Wasn't all that long either.

Oh you mean the fact that it failed at the weld, spitting a piece of weld out and then progressed more than 270° around the chain stay, well there is that I suppose
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Re: Hmm small crack in chain stay ...

Postby master6 » Fri Apr 27, 2012 4:58 pm

I assume that the definition of "large crack" would go something like:-

" A place where you might park a large truck" :)
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Re: Hmm small crack in chain stay ...

Postby rustychisel » Fri Apr 27, 2012 5:52 pm

"that's not a crack. This is a crack."


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Re: Hmm small crack in chain stay ...

Postby r2160 » Fri Apr 27, 2012 7:14 pm

Have you taken the bike back yet? How did you go?

cheers
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Re: Hmm small crack in chain stay ...

Postby trailgumby » Fri Apr 27, 2012 9:22 pm

rustychisel wrote:"that's not a crack. This is a crack."


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That's not a crack, that's a bike rack. :lol:
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Re: Hmm small crack in chain stay ...

Postby raistian » Fri Apr 27, 2012 10:34 pm

trailgumby wrote:That's not a crack, that's a bike rack. :lol:


Soft padding guarantees zero scratch* on your bike^.

* may occasionally leave brown marks - this is harmless but not odourless :shock:
^ frequent use allows you to fit more bikes over time
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Re: Hmm small crack in chain stay ...

Postby elStado » Fri Apr 27, 2012 10:59 pm

I wouldn't worry about it. What's the worst that could happen?
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Re: Hmm small crack in chain stay ...

Postby bp2 » Sat Apr 28, 2012 10:24 am

In your first photo if you look at the dropouts you have two serated marks where the wheel was tightened.
The top mark is the correct position for the wheel. The bottom mark shows that at some stage a wheel was tightened in the incorrect lower position. This could have lead to a twisting force on the lower chain stays.
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Re: Hmm small crack in chain stay ...

Postby find_bruce » Sat Apr 28, 2012 11:47 am

r2160 wrote:Have you taken the bike back yet? How did you go?
Yep took it back the next day thanks Glenn - have been told they will replace the frame - just waiting to find out told how long it will take
elStado wrote:I wouldn't worry about it. What's the worst that could happen?

You're right I am being overly cautious - I should have just kept riding it while "keeping an eye on it"
bp2 wrote:In your first photo if you look at the dropouts you have two serated marks where the wheel was tightened.
The top mark is the correct position for the wheel. The bottom mark shows that at some stage a wheel was tightened in the incorrect lower position. This could have lead to a twisting force on the lower chain stays.

Thanks for taking the time to look so carefully. Whilst I have clearly tightened the axle whilst incorrectly positioned, I would be surprised if I had ridden it like that as it is unlikely that I would have perfectly matched the mis-alignment on the other side so the wheel would have fouled the close fitting mudguards.

As I have returned the bike, I can't check for matching marks on the other side
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