Anyone Else Had This Happen?
Discussion
Was out on a shortish ride yesterday, got to the homeward half mile uphill and sat back down on the seat to settle in for the climb, only to have my seat post snap where it exits the frame.
I didn't mind too much as thankfully it was only a short distance from home and I was able to stand-pedal for the remainder. What I was more concerned about is that this is now the second time in just over a year that my Cannondale SuperSix Evo Carbon Ultegra has done this and it's only just over two years old
Has anyone else had this happen to their Cannondale?
Thankfully, my local shop were able to supply a replacement this morning while they submit the above to Cannondale for a warranty claim.
I didn't mind too much as thankfully it was only a short distance from home and I was able to stand-pedal for the remainder. What I was more concerned about is that this is now the second time in just over a year that my Cannondale SuperSix Evo Carbon Ultegra has done this and it's only just over two years old
Has anyone else had this happen to their Cannondale?
Thankfully, my local shop were able to supply a replacement this morning while they submit the above to Cannondale for a warranty claim.
never - can't believe its done that to be honest, ridden posts made by BMC, Giant, Canyon, Zipp and Bianchi and never had as much as a creak never mind a complete failure, it's not being over tighened (5Nm seems to be the normal torque setting for a post clamp)?
I guess just be thankful it wasn't the front forks or steerer.
I guess just be thankful it wasn't the front forks or steerer.
Is that an alu or carbon stem? looks like shiny metal where it's broken.
It is very weird and never seen it before in a benign environment you've mentioned; and it's your 2nd one to snap!! the educated guess would be ITS YOU riding weirdly. seems you don't sit particularly far back on the stem either.
It is very weird and never seen it before in a benign environment you've mentioned; and it's your 2nd one to snap!! the educated guess would be ITS YOU riding weirdly. seems you don't sit particularly far back on the stem either.
TheDrownedApe said:
Is that an alu or carbon stem? looks like shiny metal where it's broken.
It is very weird and never seen it before in a benign environment you've mentioned; and it's your 2nd one to snap!! the educated guess would be ITS YOU riding weirdly. seems you don't sit particularly far back on the stem either.
It's an aluminium stem, and you're right - I don't sit that far back. It is very weird and never seen it before in a benign environment you've mentioned; and it's your 2nd one to snap!! the educated guess would be ITS YOU riding weirdly. seems you don't sit particularly far back on the stem either.
What looks to have happened is there's been a hairline crack developed first on the forward side of the stem. It is noticeably darker (older). It's reached about halfway and then you can see where the crack is more "granulated" as the whole thing has given way.
I'm no stick-insect, but I weigh in at 78Kg, which I'm sure is within tolerance for the post.
The only other clue as to what might have happened is that at the bottom end of the stem, on the forward side, the paint had been worn, indicating that the stem might have been spending time in contact with the frame, maybe "pivoting" about the exit point at the top rear of the seat tube? i.e. the stem is possibly slightly undersized for the seat tube?
Super Sonic said:
After the first time I would have got a stronger post. It's not just about your weight, it's also about your riding style.
It’s not anything to do with riding style.It’s a seatpost, it’s meant to be sat on.
It’s a failure that shouldn’t happen, and at a guess it’s either the wrong diameter for the frame, or the seat tube has been manufactured out of tolerance, so the post is moving when it shouldn’t.
Super Sonic said:
After the first time I would have got a stronger post. It's not just about your weight, it's also about your riding style.
That's a load of rubbish, how on earth can you blame the rider for clearly a major manufacturer or design fault given its happened twice.Even on a £60 Halfords special I've never seen any seat post come close to falling like the OPs. Scary, as if it's happened twice now, the chances of it happening again is pretty certain I would have thought!
Yes. However I realised something wasn’t quite right before it let go altogether.
In my case it was a carbon post in a titanium frame.
I think the reason for failure in my case was due to me over tightening it as it kept slipping, despite use of carbon paste.
I replaced it with a titanium post which is far more comfortable.
In my case it was a carbon post in a titanium frame.
I think the reason for failure in my case was due to me over tightening it as it kept slipping, despite use of carbon paste.
I replaced it with a titanium post which is far more comfortable.
I had my Thomson seat post out of the frame last night to reapply carbon paste.
They use an ovalised cross section where the thicker part of the post is to fore and aft when installed on the bike, exactly where the loading will be when you’re sat on it.
I notice your post is basically a round tube of constant section.
Given you’ve had it fail twice, would imply:
- something on the frame is causing a stress raiser.
- the post design isn’t fit for purpose.
- you’re loading it in a way that is outside of the design parameters.
Personally, I would replace with a design similar to the Thomson one.
They use an ovalised cross section where the thicker part of the post is to fore and aft when installed on the bike, exactly where the loading will be when you’re sat on it.
I notice your post is basically a round tube of constant section.
Given you’ve had it fail twice, would imply:
- something on the frame is causing a stress raiser.
- the post design isn’t fit for purpose.
- you’re loading it in a way that is outside of the design parameters.
Personally, I would replace with a design similar to the Thomson one.
Pretty sure that post is 'D' shaped as opposed to round? So unlikely there are any after-market posts that would fit
It looks like you have the saddle quite far back i.e. clamped towards the front of the rails which would obviously increase the leverage on the post when you are seated. Do Cannondale make a post with more set-back?
It looks like you have the saddle quite far back i.e. clamped towards the front of the rails which would obviously increase the leverage on the post when you are seated. Do Cannondale make a post with more set-back?
Edited by addey on Friday 12th August 11:22
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