Mystery rear wheel issue
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  1. #1
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    Mystery rear wheel issue

    I am a relatively inexperienced bike owner. I recently had my local LBS in Tokyo install Mavic Ksyrium wheels on my Specialized road bike with 105 components. To save money, I purchased the wheels online from an auction site. They were "new" when I got them. I had no issues with my bike prior to these wheels being installed.

    Now, only when I descend a pretty steep slope, or, ride across very uneven road, a pretty strong, audible vibration from the rear kicks in and slows the bike down. It feels like it could theoretically be the brakes grabbing, but the grabbing or friction is very constant and uniform, not intermittent like brakes rubbing the wheel in one spot due to a lack of wheel alignment (which there is a bit of) seemingly would cause. And, the brakes etc. were just fine prior to the new wheels being installed. This happens 4-5 times every ride. When the slope or pavement evens out, the rubbing goes away.

    The local LBS now refuses to discuss since they can't reproduce the problem up and down their block, and another higher end LBS won't deal with any bike they didn't sell. So it looks like I might have to figure this out myself. Has anyone experienced this? Given the history of the problem, it seems like the cause would be either in the wheel itself or in the installation of it.
    Last edited by Tokyoeasyrider; 02-09-2019 at 06:59 PM.

  2. #2
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    If the brakes were grabbing you'd be able to look back and see the pads not fully retracted.

    I doubt that's your problem.

    Does this problem occur only when pedaling, only when coasting, or both?

  3. #3
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    Both, it's not a pedaling issue. A steep down slope or rough road is enacting a force on the bike such that the rear is acting up in this way. I even fully opened the rear brakes up and still had the problem. The friction sound is like a "grrr..." although difficult to write exactly or even mimic.

  4. #4
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    Maybe the hub isn't "freewheeling" properly?
    Does the chain go slack when this happens and you are not pedaling?

  5. #5
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    You're description rules out what I would have guessed for 'grabbing'. That being the rim isn't uniform width so would have a pulse or grab once per revolution.

    Check your brake set-up and make sure your pads are centered and hit the brake track and brake track only. If the dish of the new wheel is off compared to the previous that they were set up for that's possible. Although your description doesn't sound like that either but worth looking.

  6. #6
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    Sounds like the cassette mechanism or the rear hub bearings. If the axle turns smoothly with your fingers, the hub bearings are fine.

    Mavic freehubs are serviceable, and there is a seal between the cassette body and the hub which tends to dry out, requiring lubrication. This is my next guess.

  7. #7
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    I'm betting that it's a poorly-freewheeling freehub, and the fact that your rear wheel is less heavily loaded on a steep downhill is just allowing the rest of the wheel to vibrate more than when fully loaded. Either lubing or replacing the freehub SHOULD get rid of the problem, but then, it's a Mavic....
    "L'enfer, c'est les autres"

  8. #8
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    Maviks need the freehub lubricated at least yearly. Open that baby up and fill it with tri-flow or ? (the area where the paws are).
    If you ride in rain, probably more frequent service is required. You can tell when you need it as when you stop pedaling, the noise starts.
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  9. #9
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    Thanks for your replies

    Great insights to work with to solve this issue.

  10. #10
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    If the freehub was binding enough to cause a loss of speed, wouldn't it also cause the chain to wrap round the cassette?

    My money is on an issue with the wheel bearings.

  11. #11
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    Quote Originally Posted by dir-t View Post
    If the freehub was binding enough to cause a loss of speed, wouldn't it also cause the chain to wrap round the cassette?

    My money is on an issue with the wheel bearings.
    Yes it does, but the chain is on the front ring, which limits the movement.
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  12. #12
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    Quote Originally Posted by duriel View Post
    Yes it does, but the chain is on the front ring, which limits the movement.
    No it doesn't as the chain isn't rigid. Imagine what would happen if you were backpedaling and someone grabbed the chain near the top of (and behind) the ring - you would keep pedaling until the slack was taken out of the chain/der cage, and you would have a bunch of slack in the chain between the that person's hand and your chain ring.

    If the freewheel binds, causing drag on the cassette, the cassette will spin with the wheel and the chain would then wrap around the cassette - unless the rider pedals fast enough to match the rpms of the cassette. The OP doesn't describe this happening. This is why I think the problem is with the bearings.

  13. #13
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    OK, well I've had mavic wheels before and when it drags, it don't just lock up, it drags until it reaches the max limit of the drag which is not like grabbing it with your hand as your going down a dangerous decent and approaching a hairpin corner.
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  14. #14
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    It's probably not the rear wheel

    Peter P,
    "Does this problem occur only when pedaling, only when coasting, or both?"
    Turns out this was a great question and got me past my mistaken understanding of the symptoms. It turns out the vibration only took place when I was freewheeling and seems to originate in the area of the bottom bracket. I thought it was the back because strong vibration spread to the back and felt like it was originating there. The fact that there is only a problem at speeds over 30km/hr makes it hard to check. I thought I had been pedaling through the vibration, but I hadn't. Each time the hard vibration and noise, when freewheeling at speed on rough road, caused me to panic a bit and I didn't pedal out of it. Once I realized this, pedaling, or a smooth patch of road, or reducing speed, got rid of the vibration. The downhill symptoms were speed related, not slope related. I've taken it to an LBS and asked them to look at the bottom bracket area. If you have any ideas on causality given the more accurate symptoms now, I'd love to hear them. Thanks again.
    Last edited by Tokyoeasyrider; 02-16-2019 at 11:18 PM.

  15. #15
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    Please explain your reasoning that you think it's the BB, when your not even pedaling.
    I believe you think it's from the BB, but have my doubts.
    When talking to a mech/eng, it's better to tell them what is going on. Telling them what the cause is, unless you know for certain, is a mistake.
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  16. #16
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    Quote Originally Posted by duriel View Post
    Please explain your reasoning that you think it's the BB, when your not even pedaling.
    I believe you think it's from the BB, but have my doubts.
    I'm with duriel on this; if it's speed related, and when freewheeling, it's the rear cassette mechanism.

    Can you borrow a friend's rear wheel for testing?

  17. #17
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    Will keep investigating

    Excellent advice. I did tell them I thought the friction was coming from the BB. At least this LBS is willing to work on the bike for me unlike the others. The LBS checked the BB and apparently couldn't find anything unusual. When I get the bike back I'll see if the problem persists. If so, I'll tell them as much and ask about the rear cassette mechanism. Per posts above, would it likely be the bearings or seal between the cassette and the hub? What would be the typical approaches to fix this?

  18. #18
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    Not reasoning, more me trying to physically isolate the source of the noise vibration while traveling at 30 kph downhill on rough road in Tokyo traffic (where I ride). It really felt like the source was the BB and shooting through the crank into my shoes. My original observation though was that it was coming from the rear. And, the rear wheel is the variable that changed just before the problem surfaced.

  19. #19
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    Quote Originally Posted by Tokyoeasyrider View Post
    Excellent advice. I did tell them I thought the friction was coming from the BB. At least this LBS is willing to work on the bike for me unlike the others. The LBS checked the BB and apparently couldn't find anything unusual. When I get the bike back I'll see if the problem persists. If so, I'll tell them as much and ask about the rear cassette mechanism. Per posts above, would it likely be the bearings or seal between the cassette and the hub? What would be the typical approaches to fix this?
    I answered your question earlier, IMO. I can see why the LBS has problems.
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  20. #20
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    It takes about 5 minutes to open up that crappy mavic hub, clean and lube it then reassemble. That should do it. This is a well documented issue with mavic hubs (searching will work). If your lbs doesn't do this, get a new one or learn to do it yourself.

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  21. #21
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    Quote Originally Posted by Tokyoeasyrider View Post
    Not reasoning, more me trying to physically isolate the source of the noise vibration while traveling at 30 kph downhill on rough road in Tokyo traffic (where I ride). It really felt like the source was the BB and shooting through the crank into my shoes. My original observation though was that it was coming from the rear. And, the rear wheel is the variable that changed just before the problem surfaced.
    Let's try to clear this up. If you are getting frame vibration when coasting (also known as shimmy) then it has nothing to do with your components except perhads headset adjustment. If you are getting a howl or other loud sound when coasting, then it is almost certainly the freehub and almost certainly NOT the BB. You have not made clear what you mean by "vibration" but as others have noted, the noise of coasting is a common issue with MAVIC freehubs due to the design, and it is easy to fix with lubrication.

  22. #22
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    Your diagnosis was correct, it was the rear hub

    Lub to the rear hub is done, growling and vibration problem during freewheeling is solved. Thanks for your patience and collaboration.

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