Second bent axle - bad luck or something else?

redvision
redvision Posts: 2,958
edited October 2015 in Workshop
So, last month i noticed something wrong with my rear wheel (Mavic kysrium Elite). It felt really sluggish although the bearings seemed ok. Took it for a service which revealed a bent axle.
Since then i have been using a brand new mavic Aksium on the rear, although ride time has been limited due to a niggling knee problem.

Anyway, when out in the week i noticed that when i took my hands off the bars the bike lent towards the right - a lot! When home i checked the wheels were true and seated correctly. Went out yesterday and had exactly the same issue. Decided to drop the bike off at the lbs and they found the rear axle was bent on this wheel as well :evil: (tbh it should have been apparent because they pointed out the rear tyre had clearly worn on the one side only).

They say they can't find any fault with the frame and think it may be bad luck.
I can't recall hitting any pot holes or cattle grids, plus i weigh 73kg so not exactly heavy weight. To have this happen to two wheels in the space of a month - could it really be bad luck, or is there something else likely to be causing it?

Thanks for any advice

Comments

  • keef66
    keef66 Posts: 13,123
    I can only imagine it's very bad luck. The only axle I've ever had to replace was on my son's cheapish (read massively heavy) MTB; he'd managed to snap it clean in half jumping on and off kerbs on his paper round. (Which made the wheel flop so far it ripped the rear mech off...)

    Are these things alloy? Maybe you should try a Shimano wheel with a steel axle?
  • desweller
    desweller Posts: 5,175
    It would amaze me if you have really bent your axles.

    All modern wheels feature bearings near to the dropouts. It is practically unheard of to bend or break axles in freehub wheel designs because the bending moment is so small as a result.

    I would try a different LBS; the analysis of yours doesn't pass the smell test IMO.
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  • keezx
    keezx Posts: 1,322
    edited October 2015
    Not quite true, with most of the cartridge bearing axles the load of the right side wheelbearing still is somewhere near the middle, the load of the chain is taken by the freehub bearings, though.
    A bent axle is indeed rare/unlikely because of the oversize design.
  • keef66
    keef66 Posts: 13,123
    As I understand it Shimano patented the idea of the drive side bearing at the outboard end of the freehub, so by inference all other manufacturers' hubs must have it further inboard.

    That and the steel axles make the lower end Shimano rear hubs a more robust proposition than similarly priced ones from other manufacturers.
  • desweller
    desweller Posts: 5,175
    The Shimano freehub design gets its strength from the splined boss on which the freehub is mounted. The freehub body is held on with a hollow screw through which the axle passes.

    On Mavic wheels there is a long boss in the hub which pokes through the freehub body. There is a bearing in the end of the boss, so it is pretty close to the dropout I would say.

    I can't see how you could bend an axle with that design (although it is absolutely minging in other ways).
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  • keezx
    keezx Posts: 1,322
    On Mavic hubs the right side bearing is indeed further outside then on most other cartridge bearing hubs.
    Causing the bearing problems with the freehub.....
    Looks bend-resitant though.
  • redvision
    redvision Posts: 2,958
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19730124#p19730124]DesWeller[/url] wrote:
    It would amaze me if you have really bent your axles.

    All modern wheels feature bearings near to the dropouts. It is practically unheard of to bend or break axles in freehub wheel designs because the bending moment is so small as a result.

    I would try a different LBS; the analysis of yours doesn't pass the smell test IMO.

    Too late to try another LBS - they replaced the axle and the wheel is ready to pick up today. They also told me on the phone they are going to get in touch with Mavic about the Aksium as the wheel is only a few weeks old. Doubt they will offer any warranty replacement or anything though as they will no doubt claim 'wear and tear'.

    I really hope that it is just a coincidence. If it does happen again then i think i will get another LBS to have a look at the frame as i can't think of anything else which would be causing it.

    Thanks for all the replies.
  • desweller
    desweller Posts: 5,175
    Do you have the old axles?
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  • redvision
    redvision Posts: 2,958
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19730676#p19730676]DesWeller[/url] wrote:
    Do you have the old axles?

    Not the Ksyrium.
    I am picking up the Aksium later today so will ask for the axle - although would this stop them putting a claim in with Mavic??
  • desweller
    desweller Posts: 5,175
    It's yours. I would always ask to see the evidence that it's bent, you don't have to take it away with you.
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  • redvision
    redvision Posts: 2,958
    [url=http://www.bikeradar.com/forums/viewtopic.php?p=19730697#p19730697]DesWeller[/url] wrote:
    It's yours. I would always ask to see the evidence that it's bent, you don't have to take it away with you.

    Good point! You're right, as you say, it's mine. Will defo ask to at least see it.
    Wish i had asked to see the Kysrium axle now... :?

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