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Carbon fork replacement?

Started by Martian Tom · · Last activity · 6 posts · 3,547 views

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01 / Original postCarbon fork replacement?Martian Tom · 16 Aug 2009 02 / This pagePosts 1–6Page 1 of 1 · chronological order 03 / Latest replyPost #6alfeng · 19 Aug 2009

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Cycling Equipment
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16 August 2009
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19 August 2009
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Martian Tom
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  1. Original post
    Martian Tom
    Archived post
    #1

    I have a Specialized Sequoia Racer/Tourer bike which I've used every day for 6 years with no major problems. It has Specialized Carbon 2 front forks (Zertz damping system, whatever that means!), which, as I understood at the time of purchase, was the strongest, lightest and overall best option. However, on flicking through the manufacturer's handbook recently, I saw (never noticed it before) that they recommend changing these forks every 3 years. I've checked with a few cycle technicians and have got a mixed response - some saying yes I should, others saying there's no need... providing there's no sign of wear or damage to the forks, which there isn't.

    I'm now confused. Replacing the forks is quite an outlay. If I'd chosen the next model up, which had rear carbon forks as well, I'd be looking at shelling out for over half the original cost of the bike.

    What do other people think about this, please? Am I tempting fate by continuing to use the bike with the original forks... or is it just a case of the manufacturers seeking to coin it by exploiting safety fears?

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  2. dhk2
    Archived post
    #2

    I think it's a case of Specialized trying to CYA (cover their asses) for legal liability in event the forks break. Suppose it was good marketing to have a feature that is intended to promote vibration damping, but to me it appears that it might concentrate bending loads and result in a shorter fatigue life of the forks....believe that arguement could be made in court anyway.

    But I don't know the basis of the 3 year recommendation, unless they are worried about the "zertz plug" debonding and falling out. Fatigue damage to the fork would be more a cumulative function of how many bumps, RR tracks and potholes you hit rather than just years or miles ridden on smooth pavement.

    If you ride a lot on bumpy rough roads, or do a lot of heavy braking (eg, on twisty descents), then maybe you're at risk of a failure. If the fork is built right though, it should give plenty of warning (ie, creaking or flexing) before snapping and throwing you to the ground. Personally, believe I'd just continue to ride while inspecting the forks closely for cracks at frequent intervals and paying attention to any flexing or cracking/popping noises you hear.

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  3. Martian Tom
    Archived post
    #3
    dhk2 said:

    I think it's a case of Specialized trying to CYA (cover their asses) for legal liability in event the forks break. Suppose it was good marketing to have a feature that is intended to promote vibration damping, but to me it appears that it might concentrate bending loads and result in a shorter fatigue life of the forks....believe that arguement could be made in court anyway.

    But I don't know the basis of the 3 year recommendation, unless they are worried about the "zertz plug" debonding and falling out. Fatigue damage to the fork would be more a cumulative function of how many bumps, RR tracks and potholes you hit rather than just years or miles ridden on smooth pavement.

    If you ride a lot on bumpy rough roads, or do a lot of heavy braking (eg, on twisty descents), then maybe you're at risk of a failure. If the fork is built right though, it should give plenty of warning (ie, creaking or flexing) before snapping and throwing you to the ground. Personally, believe I'd just continue to ride while inspecting the forks closely for cracks at frequent intervals and paying attention to any flexing or cracking/popping noises you hear.

    Thanks a lot, dhk2... they were kind of my thoughts. I use the bike purely on macadam roads - though the quality of the roads around here is pretty poor, and each trip is a (not always successful) attempt to avoid potholes. I've not had any serious crunches, and have only had one (rear wheel) spoke go in 10,000 miles of cycling. Also, I'm not heavy (170lbs) and never carry any heavy loads.

    The Owner's Book simply says:
    Warning: For your safety, Specialized recommends that carbon road forks be replaced after 3 years of use.
    It doesn't say, though, what kind of mileage they would estimate for that period... which suggests a time-related deterioration in the carbon fibre composition. Anyway, I've checked the forks thoroughly, and they are as clean as they were when I first got the bike. If I do replace them, I'll go for a longer-lasting option, I think!

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  4. artemidorus
    Archived post
    #4

    Well-made composites are not supposed to fatigue, but those zertz things might age. I would probably aim to replace the fork just to get rid of that damn zertz thing, then keep the replacement indefinitely.

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  5. Martian Tom
    Archived post
    #5
    artemidorus said:

    Well-made composites are not supposed to fatigue, but those zertz things might age. I would probably aim to replace the fork just to get rid of that damn zertz thing, then keep the replacement indefinitely.

    Thanks. But what exactly are the Zertz things? 😕

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  6. alfeng
    Archived post
    #6
    Martian Tom said:

    Thanks. But what exactly are the Zertz things? 😕

    The ZERTZ dampeners are the visible, white, semi-oval inserts that can be found in the rear seat stays, the seat post and/or the fork which some "engineer" at Specialized must have thought would look cool/rad/whatever if you (the cyclist) could see them.

    I presume the Zertz inserts are made with a type of neoprene ...

    A piece of cork would do the serve the same purpose, but probably not last as long.

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