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2 broken/cracked seat stays on 2 different bikes, in 2 years. What gives? Is this common? Bad luck? I'm a bad crasher? I do ride quite a lot of miles and put my bikes through the wringer, but c'mon!!

Both bikes were high end carbon, same brand but different models. Both were seemingly minor crashes on the drive side, no injury to myself. Also, I'm a 120 lb female, not like I'm a big aggressive rider.

I don't really have a question here, I just wanted to vent. Thanks if you're reading this!!!
 

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since 4/10/2009
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With carbon bikes, there's certain things they don't handle well. If the wrong spot on the frame strikes a rock just so, then it may well crack.

On the plus side, it may be repairable. And if done well, it could well wind up stronger than before.
 

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Wanna ride bikes?
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Breaking a frame sucks regardless of the situation. Are you unlucky that they both broke in a (assuming?) minor ish crash? Yes. Is it uncommon for carbon to crack when it's introduced to sharp objects? No.

If it makes you feel any better I broke 5 frames in a 5 year stretch. 4 were steel frames, one was aluminum. Granted I'm 210lbs, fairly strong rider, not gentle, and none were due to a crash.

Mountain bikes don't live an easy life, and **** happens. My motto is don't buy carbon if you can't afford to replace it. Some brands build more durable frames than others though...
 

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Quit tearin‘ nice chit up.
Simple enough.
It ain’t cool, it ain’t smart.
It ain’t really an answer, I just wanted to vent....
 

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I broke 2 carbon frames in two years. Both were replaced with aluminum. As someone else said, all it takes is an impact on the wrong spot. My road bike lost garage brawl with a wheelbarrow and my YT cracked from a impact on the rear derailleur.

I've been really happy with the switch the metal. My Knolly Fugitive picked up a loose baseball sized rock with the spokes going about 20mph and whipped it around into the seatstay. Ripped out three spokes before locking the wheel. Paint damage only. Rode it home. Pretty sure that would of obliterated any carbon frame.
 

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That's why I only buy non-carbon mountain bikes.

They may say whatever they want, but carbon is not up to the task if you want a DURABLE mountain bike.
 

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No it's not normal to crack the seatstays in fairly minor crashes. The pic below is from my Hightower LT tumbling down Windrock. It looks bad but structurally fine. If you're talking about two bikes
of the same brand/model then I think that's more likely the cause than the material. Some bikes are built more stout (and heavier) than others.
1910425
 

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No it's not normal to crack the seatstays in fairly minor crashes. The pic below is from my Hightower LT tumbling down Windrock. It looks bad but structurally fine. If you're talking about two bikes
of the same brand/model then I think that's more likely the cause than the material. Some bikes are built more stout (and heavier) than others.
View attachment 1910425
You can't say for sure if that carbon is structurally sound unless you X-Ray it.

The problem with carbon is not that it fails suddenly without warning, it doesn't. The problem is that, lots of times, you can't see the damage without specialized means, and carbon can fail in a multitude of ways that can't be seen wothout specialized equipment: delamination can be internal, bad epoxy, bubbles under the surface... most frames don't have significant defects from the factory, but can develop them after impacts.

And impacts happen everyday on a mountain bike without even having to fall: your tire can throw rocks at various parts of the frame, for example.

That doesn't usually happen with aluminium. You can easily see if it's dented or cracking if you bother inspect the frame. Moreover, dents don't make the frame fail suddenly if they're small. Most of the time they'll be fine, and when they're not, they'll probably develop a crack that grows slowly.

Most sudden failures on aluminium frame happen at welds because of welding defects, but that's quite unusual, and most of the times you can see the crack grow before failure anyway.
 

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Carbon has two weaknesses. Abrasives and sharp rocks. Unless you're riding on sandpaper, you don't have to worry much about the first (fun fact, you can hand sand a carbon steerer tube down in no time). The second...roll of the dice. Carbon usually does okay. Usually.
 

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Hmmm... 120 lb non aggressive rider breaking two frames in the same area from the same brand... I'd change brands. But that's just me.
Yep exactly. I would have words with the manufacturer. Sounds like it’s a weakness in the frame in the same spot.

I would definitely change brands.
 

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seems like Guerrilla Gravity has a good thing going on with their carbon frames. at the moment, if I wanted to buy a carbon fiber frame (I don't, but hypothetically), it's one of the few I would trust.
 

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seems like Guerrilla Gravity has a good thing going on with their carbon frames. at the moment, if I wanted to buy a carbon fiber frame (I don't, but hypothetically), it's one of the few I would trust.
So good, none are available.. oh, that's pretty much everywhere though
 
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