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Collin's Dad
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Discussion Starter · #1 ·
While removing a blinkie light clamp from low on my seatpost last night, I noticed and very fine line going diagonal from the rear of the post. It was probably only 1/4" or so, stair stepping diagonal, I could feel an edge on it. I removed the post and it was crushed/cracked from the cut out area of the seat tube, the diagonal beginnings of the crack I saw originally coming from this area. No, I didn't over tighten the clamp, always used a torque wrench, went lower than the max torque on it (max printed on the post says 70inlbs, I used 65 in lbs always, well the 2 times I removed the post before).

The post came stock on my 04 cr-mo Allez. I'm not sure how long it had been like that, but I'm glad I caught it before it busted on me while out on a ride. I noticed from specialized's website that the 05 pave posts dropped the max torque for the seat post clamp to 55in_lbs (mine is an 04 and read max torque of 70in_lbs printed on the post itself). The post was at least inserted into the frame 1"-2" deeper than the minimum amount that needed to be in the frame. Rider weight 155lbs. Age of post: 3 months shy of 2yrs.

Took the post into the LBS where I bought the bike, they are sending it to specialized to see what they have to say about it. I assume my post had the same 1yr warranty that 05's did, but can anyone confirm this? What bother's me is that 1) I never torqued within 5 in-lbs of the max and 2) the following year posts have a reduced max torque, like this was a known problem.

If you have an 04 pave seatpost you might want to check it out often and reduce the torque on the clamp to 45in-lbs (recommended torque on 05 posts). My LBS was sending the post into specialized to see what they have to say, I'll reply to this message with what I find out, not expecting much since it's >1yr but it'd be nice if I receive a replacement for reduced or free.
 

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75 Posts
I wore out a carbon fiber kayak paddle through normal paddlng use. I didn't have a catastrophic failure, it just started creaking with every stroke that required some torque. The fibers and their lamination couldn't stand the repeated stresses over time (~5 years) I wonder when these carbon fiber frames are going to show a breakdown in the fiber from torque stress and flex. Weren't these frames and fibers designed for racers like the tour where if there is a failure, they just replace them. Longevity wasn't a factor in their design. Whereas many everyday people are buying bikes made of these light weight materials and foolishly expecting them to last?
 

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Cat 6 rider
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3,119 Posts
kayakado said:
I wore out a carbon fiber kayak paddle through normal paddlng use. I didn't have a catastrophic failure, it just started creaking with every stroke that required some torque. The fibers and their lamination couldn't stand the repeated stresses over time (~5 years) I wonder when these carbon fiber frames are going to show a breakdown in the fiber from torque stress and flex. Weren't these frames and fibers designed for racers like the tour where if there is a failure, they just replace them. Longevity wasn't a factor in their design. Whereas many everyday people are buying bikes made of these light weight materials and foolishly expecting them to last?
The weird part is that none of these bike parts come with a life expectancy. If it just said, "Replace after 20,000 miles," that would be fairly easy to calculate. Maybe the failure mode is so easy to detect (like your creaking paddle, or big and obvious cracks developing before breaking) that the bike companies figure there's no need for a warning. My fear is that I'll be doing a descent and have something just snap due to fatigue, and I had no way of knowing it was coming to the end of its service life because there is no service life given.
 

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20,000 miles would mean I'd need to replace my frame every 4 years and some of my friends' bikes would need to be replaced every other year. For $3-5,000 I'd like to have a somewhat longer useful life on a bike frame. It will be interesting to see how this will develop. My next frame will be titanium.
 

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confirmed masher
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1,712 Posts
manfuacturers would actually have to be responsibile for something if they put somehting on the label, and they're just not prepared to do that. plus it's not like there are parts inside that will wear down from use.
 

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Cat 6 rider
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3,119 Posts
kayakado said:
20,000 miles would mean I'd need to replace my frame every 4 years and some of my friends' bikes would need to be replaced every other year. For $3-5,000 I'd like to have a somewhat longer useful life on a bike frame. It will be interesting to see how this will develop. My next frame will be titanium.
That was just an example. I have no knowledge of how long a frame will last, regardless of material. Both titanium and aluminum are fairly "brittle" metals that are subject to metal fatigue. There are ways to engineer around it, but you're stuck with engineering prowess of the designer which few of us are qualified to analyze. (I expect the extremely heavy, contoured weld lines on modern bike frames are designed to spread the load and prevent bending and vibration at frame joins that could lead to fatigue.)
 

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Cat 6 rider
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OneGear said:
manfuacturers would actually have to be responsibile for something if they put somehting on the label, and they're just not prepared to do that. plus it's not like there are parts inside that will wear down from use.
Specialized put, in writing, that the frame is guranteed for life. I would think that would be a more precarious promise than a set number of years or miles.
 
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