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Cracked frame from a branch?

4K views 14 replies 11 participants last post by  plummet 
#1 ·
I had an interesting ride last Sunday on my 429trail. I was riding along up a hill when a quarter inch branch from the ground becomes lodged between the derailleur and the spokes. I stop and the hanger is bent fairly well. I'm thinking no big deal the spokes are fine, the derailleur is fine just the hanger is bent like it should be. I coast home mostly all downhill... luckily I had just climbed a half hour or so and it was all free wheeling back to the car.

I take the bike to my local shop to get the hanger straightened and buy a spare hanger . I was shocked when the mechanics said there was a crack. I had not even noticed but there it was, a
big crack in the frame from where the hanger bent. Let's see if Pivot warranties this... there is no way a frame should crack from a 1/4 inch stick that doesn't hurt the derailleur or spokes. Anyone ever seen anything like this?

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#3 ·
I will quite frank here, if you expect a slightly bent aluminum derailleur hanger to crack your frame you sure don't expect much out of a mountain bike. IA slightly bent sacrificial 20 dollar hanger certainly should not crack the frame on a 5500 bike, if that's not a manufacturing default I don't know what is.

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#5 ·
Finding a crack after a der hanger was bent Doesn't establish when the crack occurred.
You seeing it under the rear triangle only establishes when you saw it. Could have been caused months ago. Full analysis of the crack and surrounding area is probably required.
I doubt any of us on this forum can identify the cause from your pics.
In my experience Pivot doesn't shirk their warranty responsibilities. In my exptrience if it's a legit manufscturing issue they will step up
Good luck
 
#7 ·
I agree w that. If you notice the original post is holy crap this is odd, has anyone seen anything like this before? There is no more to the story. I'm a 45 yo casual rider that doesn't even come close to push this bike anywhere near its limit. I do know the bike is close to perfect for long rides in my geography. This was just a bit of a wth!

For the earlier comment on how long the crack has been there, truthfully I can't say for certain it just seemed to be cause and effect to me but I didn't notice it 2 to 3 weeks previously when it was on the stand for a chain replacement. The bike is only 9 months old.

The same question remains, anyone seen anything this odd before?

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#8 ·
I don't think it's a manufacturing defect, but possibly bad engineering on Pivot's part.
The hanger design and seat on the chainstays isn't very robust and it seems to me that bending the hanger with enough force and at certain angle could very well pinch the carbon and crush it. This is probably what happened.

It could've been that the hanger was slightly loose on the frame and branch lifted it to the outside and crushed the frame between the hanger and the axle.

Generally, I think it's an unfortunate event combined with (too) delicate frame and unforutnate choice of material in this case (carbon). If it were aluminium, nothing would've happened or at worst slight scratch or small indentation.

It's not all lost, you can easily repair carbon and even if Pivot doesn't acknowledge it as a warranty case, get it fixed and don't worry about it.
 
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