Can I trust carbon fiber frame after twenty odd years?

555

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New England
Trek Y-11. Had the bike for over twenty years and decided to get it back on the road. Should I? Was riding it up until about 2010 and then got distracted with other toys. I'm about 255 to 270lbs. If the consensus is that I should keep riding it, the next question is what to do about the front fork. Replace? Is that thing serviceable these days? Thanks for the help and have a good weekend. [Linked Image] [Linked Image]
 
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4,843
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Lakeville, MN
Odds are the elastomers in that fork are toast after this many years. You can source replacement elastomers if you really want to - they run about $55 for a kit if you can find them. Had that fork on a Gary Fisher Hoo Koo E koo. Hard riding killed the elastomers and I upgraded to a different fork (which led to a brake upgrade).
 

555

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Thanks MNgopher. Figured it was time for a new fork but nice to have confirmation. Thanks CT8. I was curious if any one else had experience with this model. I will call Trek.
 
IMO you're pushing your luck with your size and that frame. You say back on the road, do you mean road/gravel riding or gnarly trail riding? That's likely an 80mm travel fork, I had one on something but forget. Might find elastomers on Ebay or check with RS. The bike really isn't worth an new fork and odds are the rear shock isn't doing much damping now. 20 years ago was in the early years of CF bike frames. TREK was big on these from 1995 to around 2000. They were known for being very lightweight and pogo'ing like crazy while pedaling. I sure wouldn't ride it hard.
 

555

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Thanks AZjeff. Just a cruiser bike at this point. I like using things for their intent but might make an exception here. As you mentioned, the rear suspension geometry played havoc with chain length as the suspension compressed and relaxed. Thanks Taildragger. I believe you are correct. Lots of good memories, and trails on that bike, so if don't use it I still like looking at it.
 
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Just an FYI, CF does not fatigue in the manner that aluminum does. Aluminum and many other metals can take a certain number of cycles before cracks start. Carbon fibers remain intact over an infinite number of design load cycles, yet CF yields suddenly when overloaded. The CF spars on Extra 300 aerobatic aircraft are subjected to 10 or even 11G of loading on a regular basis. Because it's well within it's design load limits, no fatigue damage is being done and decades of use does not weaken it. Same with the Boeing 787, years of turbulence, heavy fuel loads and passengers does not weaken the composite structure. There are other problems with certain CF bike frames though. The bottom bracket and other metal components are often installed with an epoxy that is different (less robust) from the one used in the composite. On some frames, those epoxies can degrade over time and on some models, corrosion at the CF/metal interface can become a problem. It would be a good idea to research your frame and see if it was prone to problems. If not, then ride it with confidence. It's good to keep in mind that on composite structures, paint cracks do not indicate material cracks. Composites can flex and paint, especially old paint, often does not.
 
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Quote: "Trek Remedy 9.9 Broken yesterday.......Top tube severed in 2 places, Down tube severed in 1 place, and cracked severely at BB...A little wide on turn and front wheel caught the face of a cut tree that is about 2.5 in diameter. Fork is fine and the Easton carbon wheels are perfect.......Craziest thing I have seen on a bike yet. Bum calf but other than that all is well physically" It's good to note that this is the type of failure CF frames experience. A sudden overload, and sudden yield (complete failure) . It's not due to years of use or age. A metal frame is more likely to deform, dent or bend in such situations. But the result is the same, a useless frame. [Linked Image from forums.mtbr.com]
 
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9,635
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Ontario, Canada
I guess if you can find another bike, retiring the trek isn't a terrible idea. If you can't find a bike at the moment I'd just have a careful look at everything Cujet suggests and ride it on the road and rail trail type stuff. If the fork has collapsed a bit you can just lower the back end to match. Also I'd ditch the toe clips, as I assume your as old as me and don't need to have a silly fall at a stop sign...
 
Originally Posted by 555
Thanks for the responses. Decided to look at some used bikes and retire the Trek.
I think that's the right idea. FWIW, the Trek Y-bikes are quite iconic and yours is probably worth something to somebody into retro MTBs. There are quite a few Instagram pages dedicated to the genre with lots of pics of anodized, CNCed parts that still make me drool 25-30 years after they were made. Modern stuff is leaps and bounds better but just doesn't have the look, kind of how a nice carb looks so much better than an FI set-up even though the fuel injection is better in every measurable way. All this to say don't throw it out, You should be able to find it a good home, some bike shops and cafes hang classic bikes from the ceiling.
 
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555

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Originally Posted by Surestick
Originally Posted by 555
Thanks for the responses. Decided to look at some used bikes and retire the Trek.
I think that's the right idea. FWIW, the Trek Y-bikes are quite iconic and yours is probably worth something to somebody into retro MTBs. There are quite a few Instagram pages dedicated to the genre with lots of pics of anodized, CNCed parts that still make me drool 25-30 years after they were made. Modern stuff is leaps and bounds better but just doesn't have the look, kind of how a nice carb looks so much better than an FI set-up even though the fuel injection is better in every measurable way. All this to say don't throw it out, You should be able to find it a good home, some bike shops and cafes hang classic bikes from the ceiling.
It will NOT be thrown out. Good, honest, stupid times on that bike.
 
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