Carbon seatpost catastrophe
02-06-23, 11:53 PM
#51
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That is even more problematic, if you are riding a 47cm and you need a 58 or probably larger. None of that is good and that minimum insertion line is still there for a reason and I still have extreme levels of doubt on the shop setting any of those seatposts above the minimum insertion line. I can believe they swapped them but I doubt they just left it above the minimum insertion line, I would love to talk to the faux mechanic who said that was safe and good to go.
Get a properly sized bike and you will be less likely to have minimum insertion issues.
Get a properly sized bike and you will be less likely to have minimum insertion issues.
The takeaway is wow carbon seatposts can be nasty
02-07-23, 12:04 AM
#52
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02-07-23, 01:27 AM
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The takeaway is that improperly installed components can break. The material does not matter that much.
Last edited by terrymorse; 02-07-23 at 01:32 AM.
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02-07-23, 04:12 AM
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You don't have to be infamous like the OP to have a carbon post fail under normal intended use conditions. A few years ago I had an S-Works carbon post develop a crease (no snap thank goodness) on a frame. Yes there was some post was showing but it was definitely still well above the min insertion line.
02-07-23, 06:06 AM
#56
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I am over six feet tall, but I got a 52 cm bike and needed to make it work and I did. That's the one where I broke two posts---by playing games with the insertion line. it matters. Ride what you have when you need to ..... some people can buy bikes whenever they want---I can, now, but back in the day, I rode whatever I picked up on the roadside and refit.
NO! It is pointless to have experiences if you learn the wrong lessons.
The takeway is---there are right and wrong ways to do things, and if you ignore what works, what you do will not work---might even hurt you.
CF seat posts are great in a lot of applications. But anything CF has to be treated properly. if you don't want to take extra care, sure, go with metal ... but you can damage metal frames with metal seat posts, buy ignoring insertion levels---you can ovalize or even tear the frame. You can break Anything if you abuse it enough.
The takeaway is, if you abuse anything you can get hurt .... so Don't.
Anyway ..... you have a lot nicer rides than I ever pulled out of a dumpster or picked up at the end of a driveway. Take just a little care and they will work for you for many years.
Ride on, brother.
02-07-23, 06:24 AM
#57
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Catastrophe?
Nah.
When your aluminum SP breaks and when you come to, the ambulance is there to take you to the ER. That is the real thing and not fun, trust me.
Nah.
When your aluminum SP breaks and when you come to, the ambulance is there to take you to the ER. That is the real thing and not fun, trust me.
02-07-23, 06:29 AM
#58
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That is why I never had a carbon seat post in any of my bikes.I never had trust in carbon seat posts,a guy who was doing a triathlon ona look kg171had his Look seat post fail after three years of intensive use. I prefer aluminium seat posts for many reasons.
02-07-23, 06:33 AM
#59
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02-07-23, 06:34 AM
#60
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Sure,it isn't funny but there is also the way the seat is inserted in the seat post and if it is properly tightened and is an original fit for the frame in question. And some aluminium seat posts are of bad quality,so better spend money on an expensive seat post than be sorry later.
02-07-23, 06:38 AM
#61
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I had an aluminum post break a while back. IT broke in the cast headpiece area that connects to the rails on the underside of the saddle. I felt it getting 'slushy' (?), got off, and noticed the crack. Lucky for me I was only about 2 miles/3Km from home so just rolled back. Now I just tighten the saddle adjustment until it doesn't move, then maybe a 1/4 turn more and I'm good.
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02-07-23, 06:40 AM
#62
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I had an aluminum post break a while back. IT broke in the cast headpiece area that connects to the rails on the underside of the saddle. I felt it getting 'slushy' (?), got off, and noticed the crack. Lucky for me I was only about 2 miles/3Km from home so just rolled back. Now I just tighten the saddle adjustment until it doesn't move, then maybe a 1/4 turn more and I'm good.
02-07-23, 07:31 AM
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Sure,it isn't funny but there is also the way the seat is inserted in the seat post and if it is properly tightened and is an original fit for the frame in question. And some aluminium seat posts are of bad quality,so better spend money on an expensive seat post than be sorry later.
You know nothing about the defect design of the seatpost that landed me in the hospital. I'm a retired engineer with expertise in design and product quality. Money has nothing to do with it, for sure and you are right, your post isn't funny. Case in point, if money were the solution why did Zipp have so many aluminum hub failures.
02-07-23, 07:41 AM
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If money were the solution, why does Trek's $700 Bontrager Aeolus RSL VR-C handlebar/stem fail?
WRT OP, I would trust carbon even at your weight, just don't overtighten. Carbon doesn't like compression.
WRT OP, I would trust carbon even at your weight, just don't overtighten. Carbon doesn't like compression.
02-07-23, 07:47 AM
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The thing is, it broke at the insertion point for this bike not your too small bike. If the damage was done when it was on the too small bike, it would have broken off much lower.
02-07-23, 08:32 AM
#67
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You know nothing about the defect design of the seatpost that landed me in the hospital. I'm a retired engineer with expertise in design and product quality. Money has nothing to do with it, for sure and you are right, your post isn't funny. Case in point, if money were the solution why did Zipp have so many aluminum hub failures.
02-07-23, 08:44 AM
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To me that seat post doesn't look authentic. Looks like s chinese knock off "Bontrager" post from ebay or Amazon.
02-07-23, 08:46 AM
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02-07-23, 08:49 AM
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Of course, I had one (American Classic) fail when I was solo above Lake Casitas. Luckily I did not fall.
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02-07-23, 09:09 AM
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The original factory carbon seat post failed on my 2013 Specialized Tarmac. I weigh 150 pounds and it was correctly inserted in the frame. I was two miles from the Specialized dealer who replaced the post but charged me because the warranty was long expired. Stuff happens.
02-07-23, 09:11 AM
#72
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I will probably get blistered for this but this is my opinion...
A carbon seat post makes no sense to me. Carbon is EXTREMELY strong, as long as it is not compromised. A crack, a scratch, a crushed area OR over-stressing in my opinion can all compromise a carbon item (seat post, wheel, frame, fork, etc). That small circumference where it comes out of the seat tube is a vulnerable place. Over-tightening, a fall, or anything that stresses that one small area over time or repetitively can be a ticking catastrophe.
Carbon is great stuff but I would never put a carbon seat post on one of my bikes.
A carbon seat post makes no sense to me. Carbon is EXTREMELY strong, as long as it is not compromised. A crack, a scratch, a crushed area OR over-stressing in my opinion can all compromise a carbon item (seat post, wheel, frame, fork, etc). That small circumference where it comes out of the seat tube is a vulnerable place. Over-tightening, a fall, or anything that stresses that one small area over time or repetitively can be a ticking catastrophe.
Carbon is great stuff but I would never put a carbon seat post on one of my bikes.
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02-07-23, 09:43 AM
#73
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I will probably get blistered for this but this is my opinion...
A carbon seat post makes no sense to me. Carbon is EXTREMELY strong, as long as it is not compromised. A crack, a scratch, a crushed area OR over-stressing in my opinion can all compromise a carbon item (seat post, wheel, frame, fork, etc). That small circumference where it comes out of the seat tube is a vulnerable place. Over-tightening, a fall, or anything that stresses that one small area over time or repetitively can be a ticking catastrophe.
Carbon is great stuff but I would never put a carbon seat post on one of my bikes.
A carbon seat post makes no sense to me. Carbon is EXTREMELY strong, as long as it is not compromised. A crack, a scratch, a crushed area OR over-stressing in my opinion can all compromise a carbon item (seat post, wheel, frame, fork, etc). That small circumference where it comes out of the seat tube is a vulnerable place. Over-tightening, a fall, or anything that stresses that one small area over time or repetitively can be a ticking catastrophe.
Carbon is great stuff but I would never put a carbon seat post on one of my bikes.
Reduces bike weight. Soaks up chatter. I have carbon seat posts on all 7 of my bikes.
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02-07-23, 10:20 AM
#74
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This is a safety issue. Government-mandated "FRAGILE" stickers on carbon seatposts might not be enough, so maybe "DAINTY" stickers should be used instead. It seems to me that "THIS SIDE UP" stickers in addition would not necessarily be superfluous.
I found a video of influencers debating the merit of carbon seatposts:
Listen closely for the REAL reason they are so preferred!
I found a video of influencers debating the merit of carbon seatposts:
Listen closely for the REAL reason they are so preferred!
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02-07-23, 10:20 AM
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