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  1. #1
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    Repetitive noise when freewheeling (Shimano Deore).

    Hi all,

    I get a repetitive "grinding" noise when freewheeling (none when pedaling), which relates to the speed of travel. The noise varies according to pedal position, some positions it ceases, some positions it doubles in speed.

    It got slightly better when I sprayed a lot of lube into the end of the cassette area.

    The bike is a 1999 Wheeler 4900ZX (bought in Asia), and I had the entire transmission (including cassette, hubs, etc.) replaced with Shimano Deore, only a few months ago (and the rims replaced a few years before), and I only use it a few hours per week (mostly on back roads, usually dry).

    What could the problem be? Could it have been caused by incorrect installation? Is there any possibility of danger from this problem, or can I ignore it?

    One of the challenges is that I am in Thailand, the transmission parts were bought by someone else on my behalf (so I have no possibility of warranty), and installed by the most recommended bike shop, who now take zero responsibility for the problem (and even deny they have the tools to have done the installation at all), and presumably the few other bike shops around here are even worse.

    Any info appreciated

    Chris

  2. #2
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    I should have mentioned it's a mountain-bike, with 3x9 gears.

  3. #3
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    It's likely to be your freehub. One of my bikes does this. It happens quite a bit on Shimano hubs as they get old, but I'm surprised its doing it on a new hub.

    You can either get another freehub or lubricate the existing one. It's probably simpler to replace the freehub if it bothers you.

    Tim

  4. #4
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    Freehub is the most likely candidate, but just to review other ideas

    With the bike still, hanging the seat off something like a tree branch or hanging from a rope, just get the back wheel off the ground. Give the rear wheel a spin. If nothing is moving except the hub and wheel and you hear a grinding sound, it's probably the freewheel.

    do the same thing, but occasionally turn the pedals forward. If the sound goes away when you pedal, it's definitely the freewheel. If it still makes the same sound, the bearings inside the hub might have some grit or something in them. Learn to repack hub bearings (youtube search or ask). If you have to replace the freehub, you'll need to do this anyway.

    A way to check if the bearings are going bad is to simply remove the wheel from the bike and turn the axle. If it's nice and smooth, it's good. If you feel any play or it's rough, repack the bearings.

    Since you mentioned the sound can come and go based on pedal position, you might have a loose rear derailleur pulley. This is a tricky part to your problem. Normally pedal and chain position won't have any affect on a freehub unless it's simply positioning the freehub/cassette in a specific orientation so gravity is pulling down on a completely destroyed spring/pawl inside the freehub. If this is the case, lift the rear wheel off the ground, give it a spin, and gently turn the pedals to see if the freehub is making different grinding sounds based on the orientation of the cassette.

    End of the day, I'd get tools and fix it yourself. lots of youtube videos on how to do it, and it's really quite easy once you try. Parts you'll need:
    Chain whip
    Cassette removal tool
    cup/cone wrench
    normal wrench (cresent, open end, or second cup/cone wrench)
    grease (car axle grease, white lithium grease, black lithium grease, boat trailer axle grease[sometimes called marine grease])
    larger hex key to remove the freehub. (I think the shimano deore 525 hub uses a 12mm hex key, have to look it up. Might want access to a vice to hold the hex key it. That bolt is in there tight.)
    "a hundred travel books isn't worth one real trip"

  5. #5
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    Thanks very much for the info !

    Chris

    Quote Originally Posted by watts888 View Post
    Freehub is the most likely candidate, but just to review other ideas

    With the bike still, hanging the seat off something like a tree branch or hanging from a rope, just get the back wheel off the ground. Give the rear wheel a spin. If nothing is moving except the hub and wheel and you hear a grinding sound, it's probably the freewheel.

    do the same thing, but occasionally turn the pedals forward. If the sound goes away when you pedal, it's definitely the freewheel. If it still makes the same sound, the bearings inside the hub might have some grit or something in them. Learn to repack hub bearings (youtube search or ask). If you have to replace the freehub, you'll need to do this anyway.

    A way to check if the bearings are going bad is to simply remove the wheel from the bike and turn the axle. If it's nice and smooth, it's good. If you feel any play or it's rough, repack the bearings.

    Since you mentioned the sound can come and go based on pedal position, you might have a loose rear derailleur pulley. This is a tricky part to your problem. Normally pedal and chain position won't have any affect on a freehub unless it's simply positioning the freehub/cassette in a specific orientation so gravity is pulling down on a completely destroyed spring/pawl inside the freehub. If this is the case, lift the rear wheel off the ground, give it a spin, and gently turn the pedals to see if the freehub is making different grinding sounds based on the orientation of the cassette.

    End of the day, I'd get tools and fix it yourself. lots of youtube videos on how to do it, and it's really quite easy once you try. Parts you'll need:
    Chain whip
    Cassette removal tool
    cup/cone wrench
    normal wrench (cresent, open end, or second cup/cone wrench)
    grease (car axle grease, white lithium grease, black lithium grease, boat trailer axle grease[sometimes called marine grease])
    larger hex key to remove the freehub. (I think the shimano deore 525 hub uses a 12mm hex key, have to look it up. Might want access to a vice to hold the hex key it. That bolt is in there tight.)

  6. #6
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    It's the freehub, it is very common for some of them to make the type of oscillating 'grinding' noise you're describing, especially Shimano ones IME. It's nothing to be concerned about but they can be quieted a bit by applying some lube (Dumonde liquid grease is good) in the backside of the cassette, which requires removal to do so.

    It won't hurt anything to leave it as is though.

  7. #7
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    Good to know, thanks !

    Chris

    Quote Originally Posted by J.B. Weld View Post
    It's the freehub, it is very common for some of them to make the type of oscillating 'grinding' noise you're describing, especially Shimano ones IME. It's nothing to be concerned about but they can be quieted a bit by applying some lube (Dumonde liquid grease is good) in the backside of the cassette, which requires removal to do so.

    It won't hurt anything to leave it as is though.

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