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Thread: alpha q fork inserts

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    Default alpha q fork inserts

    putting out this feeler for a spare insert for an alpha q cx-20
    my understanding is that the steerer tube walls are too thin (hence, inner diameter too big) to use the corner cycle shim, or to safely use an expander plug as i had originally planned. i tried the local shops, tried cervelo (apparently they use shims of a different diameter)
    so if any of you fine framebuilders have a spare one, i'm all yours.

    thanks

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    Default Re: alpha q fork inserts

    Do you know the I.D. of the steerer? If it's a standard size a local metal supply shop may be able to provide you with something that would work.

    "or to safely use an expander plug" - The expander plug doesn't have to be that tight. It really only needs to have enough grip to not slip while adjusting the headset. And then it should act as a reasonable reinforcement to the clamping forces of the stem as well if it's aligned with the center of the stem clamp. I can't imagine a scenario where this isn't true unless the combined maximum number of spacers and the length of the insert puts the steerer insert below the the top part of the headset (reinforces the steerer where it engages the headset) but I have a hard time believing any company's engineering department would put the critical part of the structure of their product in the hands of an end consumer. And even if they did, the liability lawyers and insurance companies wouldn't. So, use an expander plug, just don't crank it in there.

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    ldamelio's Avatar
    ldamelio is offline emperor of time, space and all dimensions known and unknown
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    Default Re: alpha q fork inserts

    Sorry to disagree with the above, but the Alpha Q are frighteningly thin without the shim and I wouldn't just put an expander plug in and hope. I had one (yes, I know, anecdotal) snap clean off just below the insert with a properly torqued stem (no spacer pile either, just 15mm). There's a reason they're out of business and this design was never popular. Get an insert or have one machined for you and do it right for this mission (and health) critical piece.
    Lou D'Amelio
    Bucks County PA

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    Default Re: alpha q fork inserts

    Quote Originally Posted by ldamelio View Post
    Sorry to disagree with the above, but the Alpha Q are frighteningly thin without the shim and I wouldn't just put an expander plug in and hope. I had one (yes, I know, anecdotal) snap clean off just below the insert with a properly torqued stem (no spacer pile either, just 15mm). There's a reason they're out of business and this design was never popular. Get an insert or have one machined for you and do it right for this mission (and health) critical piece.
    Sometimes anecdotal evidence is enough. But if yours snapped off just below the insert I'm thinking (which is different than "knowing") that the insert may have caused the failure and at the very least, didn't prevent the failure. With a properly installed insert and a reasonable stack of 15mm of spacers, it shouldn't have failed. The fact that it failed just below the insert might suggest the strong, thicker top part of the steerer that was reinforced by the insert transferred an undue amount of force to a thin part of the steerer (is "stress riser" the right term?) and caused the failure. This might be an argument against tracking down an insert because a more gradual dissipation of forces along the length of the steerer might be better, or maybe it's an argument for a full length steerer reinforcement, because you need to be concerned about stress risers mid way down the steerer when using the original insert, so off to the local machine shop.

    But what it all really means is, there's no amount of money saved using a fork that hasn't been made for 6 years when compared to the cost of replacing your front teeth, so maybe you need to pick up an Enve or a 3T fork with a warranty and a going business concern behind it that you can sue if you do lose your front teeth.

    Anecdotal evidence, part 2: I'm a fat cyclist and have ridden the heavier versions of the Alpha Q for years (and still have one that gets ridden regularly) and never had a problem. Well, not true. The one that was a take off left at the shop one day got put on a commuter bike in 2006. In 2014 after 25000kms (very conservative estimate) of commuter riding (more than a few curbs and pot holes) on a fork that was already used to begin with, one of the drop outs loosened up. That's not bad, in my books. (anecdotal evidence is like assholes, unless that means I'm calling myself an asshole, then anecdotal evidence is proof of wisdom and good looks) (I'm not a role model)

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    Default Re: alpha q fork inserts

    I was going to say the same thing as Lou, but he beat me to it. The wall thickness of the steerer on an Alpha Q fork is maybe 1/2 as thick as that on an Enve, Reynolds, etc. fork. The aluminum sleeve provides structural support. If you read the installation instructions, they say: "WARNING: The use of the Alpha Q fork with carbon steerer tube without the supplied alloy insert voids the Alpha Q warranty and could result in serious injury or death." The instructions re cutting: "Mark the steerer tube at the top of the stem with a pencil or other marker. This mark must not be more than 80mm above the top of the headset. If 80mm is exceeded, the number of spacers used must be reduced accordingly." The reason for this measurement is that the insert was 100mm long (or longer, depending on the vintage), and it was necessary for there to be at least 2cm of insert below the upper headset race for the fork to work properly.

    http://www.alphaqbike.com/performanc...structions.pdf

    True Temper also made the Wolf forks for Cervelo, which forks Cervelo recalled. The inserts on the Wolf forks were very short.

    Wolf fork failure (pics): Triathlon Forum: Slowtwitch Forums

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    Default Re: alpha q fork inserts

    So did these forks fail when properly installed?

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    Default Re: alpha q fork inserts

    Quote Originally Posted by vqdriver View Post
    So did these forks fail when properly installed?
    Not me, but any other professional mechanic I know has ever seen a Wolf fork snapped. The recall was a "belt&braces" thing, and in my opinion it totally made sense due to the severity of a possible danger, even if this was a remote chance. Say that it could have been a 0.5%, well, you want to remove even this 0.5.

    Like already said, I too do suggest to measure the steerer's ID, and have some good guy machining a 4" long insert. You do need a certain amount of elasticity there, so I would probably not use 7075 or 20xx series of alluminium, maybe a 60xx class? Ask your man with the lathe, and have it done 0.1mm small than the steerer's ID: you do need a little gap for the Epoxy. Press the star-nut after the insert is bonded and the Epoxy well cured.
    Andrea "Gattonero" Cattolico, head mechanic @Condor Cycles London


    "Caron, non ti crucciare:
    vuolsi così colà dove si puote
    ciò che si vuole, e più non dimandare"

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    Default Re: alpha q fork inserts

    Did you ever find one? I had just picked one up for my girlfriends bike, unaware of the insert issue. I need to cut about 3 inches off. Any ideas? anyone have an old one that fell out?
    --------------------
    another jaunt
    REBAR

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