Galled Bearing Cones Puzzle - Shimano FH-M510 Hub ???

Discussion in 'Cycling Equipment' started by Steve Sr ., Dec 8, 2003.

Thread Status:
Not open for further replies.
  1. Jim Beam

    Jim Beam Guest

    Ray Heindl wrote:
    > [email protected] wrote:
    >
    >
    >>Mike Jacoubowsky writes:
    >>
    >>>If you surmised that the bearings might have been destroyed due to excessive preload, wouldn't
    >>>replacement of bearings be a requirement, not an option? Bearings cost so little compared to the
    >>>time involved in overhauling a hub, I just can't find much rationale for not replacing them, even
    >>>if everything seems OK.
    >>
    >>Bearing balls are far tougher than bearing races and if there are none available, they could be
    >>reused if they are still shiny. That could be because the races crack and spall, like an asphalt
    >>street that has been cracked from heavy traffic.
    >
    >
    > I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    > expensive to replace, or is it because they're loaded differently, or have I just been lucky?

    please, someone do the math, but this is the situation as i understand it:

    on the outer race, you have a concave surface, with a ball whose radius is smaller, but oriented in
    the same direction from perpendicular. this gives the maximal race/ball point contact area. with the
    inner race, the radiuses are oriented opposite so the point contact area between race & ball is
    minimal. and as the contact area tends to zero, the point stress rises to infinity. if the point
    contact stresses are greater on the inner race than the outer, it stands to reason that the inner
    race will spall sooner.
     


  2. Steve Sr .

    Steve Sr . Guest

    On Fri, 12 Dec 2003 07:53:03 GMT, [email protected]
    wrote:

    >Jim Beam writes:
    >
    >>>> I just reassembled my rear MTB hub (different bike) and used the adjusting method on the Park
    >>>> Tool site where you basically clamp the wheel into one side of the frame with the QR skewer and
    >>>> a spacer/washer. This compresses the axle against one of the cones but does not compress cone-
    >>>> cone as in real life. Is this a good method to use and should I somehow compensate for the fact
    >>>> that the other bearing cone is not in compression?
    >
    >>> If you close the skewer, the load is across both cones no matter if there's one or two frame
    >>> ends in the stack.
    >
    >> Sort of. You get compression of the spindle. But compressing the cone ends also exercises the
    >> small amount of play that exists in the threads. It may not be a lot, but neither is spindle
    >> compression.
    >
    >The cone is already loaded in that direction by the jam nut. There is no additional compression
    >with two dropouts in the stack. Cone and jam nut compression is irrelevant, they having more than
    >five times the cross section of the axle alone.
    >
    >>> I have heard this before, but I do not see why one would do that instead of just clamping the
    >>> wheel in the bike.
    >
    >>> What is the point? Anybody?
    >
    >I think the idea is that the cone and lock nut are accessible, not being covered by a dropout. That
    >is meaningless however, because you can't adjust it without access to the other cone that IS under
    >a dropout. It's an esoteric stunt as I see it.

    Why do you need access to the side clamped in the dropout? You only need to adjust the bearings from
    one side and the frame does a good job of clamping everything in place so that makes adjusting the
    other side easier.

    Steve

    >
    >Jobst Brandt [email protected]
     
  3. Jim Adney

    Jim Adney Guest

    On Thu, 11 Dec 2003 21:53:28 -0600 A Muzi <[email protected]> wrote:

    >Steve Sr. wrote: -snip analysis of spalled cone-
    >> I just reassembled my rear MTB hub (different bike) and used the adjusting method on the Park
    >> Tool site where you basically clamp the wheel into one side of the frame with the QR skewer and a
    >> spacer/washer. This compresses the axle against one of the cones but does not compress cone-cone
    >> as in real life. Is this a good method to use and should I somehow compensate for the fact that
    >> the other bearing cone is not in compression?
    >
    >
    >If you close the skewer, the load is across both cones no matter if there's one or two frame ends
    >in the stack.
    >
    >I have heard this before, but I do not see why one would do that instead of just clamping the wheel
    >in the bike.
    >
    >What is the point? Anybody?

    I don't see any point.

    The spacer/washer is equivalent to the other forkend.

    There might be some advantage to using 2 spacers/washers so that you knew that you weren't applying
    any bending moment to the axle, but you're really better off getting your forkends aligned anyway
    since this is something you need in the end. Then you can just forget about the spacers/washers.

    -
    -----------------------------------------------
    Jim Adney [email protected] Madison, WI 53711 USA
    -----------------------------------------------
     
  4. Jobst Brandt

    Jobst Brandt Guest

    Adam Rush writes:

    >> It doesn't take long to destroy a bearing if it has excessive preload from QR closure. This
    >> occurs often because the bearing is adjusted "perfectly" out of the bicycle, after which, for
    >> safety sake, the QR is adjusted for a tight closure. This is like putting the hub in a vise and
    >> compressing the axle. Next time check how freely the wheel swings to a stop with the QR just
    >> touching (partial closure) and then again when it is fully closed. For rear wheels, do this
    >> without the chain on the FW.

    > Okay, I've heard the "a little bit of play"-thing a thousand times and I don't doubt that it has
    > some merit, but why doesn't the same apply to bolted axels? Isn't the exact same length of axel
    > (from one outer side of a dropout to the other) getting a hefty squeeze, too?

    Lets get back to bicycling. I don't know how you do axels on a bicycle but we're talking about
    axles here.

    For solid axles with nuts, no skewer pulls ends of the axle together. Axle length between cones
    remains constant regardless of how retaining nuts that hold the wheel in the dropouts are tightened.

    > Is the resulting lateral force from a QR tightening just many times greater (if so, why should it
    > need to be?), or is it a result of a hollow axel just being easier to compress?

    I think you'll understand if you look at the forces involved and where they act. The QR skewer pulls
    axle ends together. Axle nuts and cones (pre-loaded with jam nuts) stretch the short piece of axle
    between nut and cone but have no effect on axle length between opposing bearing cones.

    > On that note, I adjust all hub bearings to the same perfection off the bike and can't recall a QR
    > wheel which didn't respond to wheel imbalances when properly clamped in. Maybe it's those
    > ShelBroCo lead valve stem cozies...

    That is one thing up with which I will not put! It makes no sense.

    Jobst Brandt [email protected]
     
  5. Jobst Brandt

    Jobst Brandt Guest

    Ray Heindl writes:

    >>> If you surmised that the bearings might have been destroyed due to excessive preload, wouldn't
    >>> replacement of bearings be a requirement, not an option? Bearings cost so little compared to the
    >>> time involved in overhauling a hub, I just can't find much rationale for not replacing them,
    >>> even if everything seems OK.

    >> Bearing balls are far tougher than bearing races and if there are none available, they could be
    >> reused if they are still shiny. That could be because the races crack and spall, like an asphalt
    >> street that has been cracked from heavy traffic.

    > I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    > expensive to replace, or is it because they're loaded differently, or have I just been lucky?

    Stress is related to the area of contact. Contact area on a cone is substantially smaller than that
    of an outer race. This is evident from geometric considerations where the outer race has a large
    concave radius while the cone has a convex radius less than half that of the race.

    Jobst Brandt [email protected]
     
  6. Jobst Brandt

    Jobst Brandt Guest

    Steve Sr. writes:

    >>>>> I just reassembled my rear MTB hub (different bike) and used the adjusting method on the Park
    >>>>> Tool site where you basically clamp the wheel into one side of the frame with the QR skewer
    >>>>> and a spacer/washer. This compresses the axle against one of the cones but does not compress
    >>>>> cone-cone as in real life. Is this a good method to use and should I somehow compensate for
    >>>>> the fact that the other bearing cone is not in compression?

    >>>> If you close the skewer, the load is across both cones no matter if there's one or two frame
    >>>> ends in the stack.

    >>> Sort of. You get compression of the spindle. But compressing the cone ends also exercises the
    >>> small amount of play that exists in the threads. It may not be a lot, but neither is spindle
    >>> compression.

    >> The cone is already loaded in that direction by the jam nut. There is no additional compression
    >> with two dropouts in the stack. Cone and jam nut compression is irrelevant, they having more than
    >> five times the cross section of the axle alone.

    >>>> I have heard this before, but I do not see why one would do that instead of just clamping the
    >>>> wheel in the bike.

    >>>> What is the point? Anybody?

    >> I think the idea is that the cone and lock nut are accessible, not being covered by a dropout.
    >> That is meaningless however, because you can't adjust it without access to the other cone that IS
    >> under a dropout. It's an esoteric stunt as I see it.

    > Why do you need access to the side clamped in the dropout? You only need to adjust the bearings
    > from one side and the frame does a good job of clamping everything in place so that makes
    > adjusting the other side easier.

    I think that if you adjust bearings, you will recall that the cone and jam nut on the other side of
    the axle are used to turn the one in contention. Clamping them in the dropout does not assure that
    the axle will not turn when applying a wrench to the far side.

    Jobst Brandt [email protected]
     
  7. Ray Heindl

    Ray Heindl Guest

    [email protected] wrote:

    > Ray Heindl writes:

    >> I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    >> expensive to replace, or is it because they're loaded differently, or have I just been lucky?
    >
    > Stress is related to the area of contact. Contact area on a cone is substantially smaller than
    > that of an outer race. This is evident from geometric considerations where the outer race has a
    > large concave radius while the cone has a convex radius less than half that of the race.

    Thanks, I'm glad it's not just luck. I'd hate to think all my cups were just waiting to fail on me.

    --
    Ray Heindl (remove the Xs to reply)
     
  8. Dianne_1234

    Dianne_1234 Guest

    On Fri, 12 Dec 2003 21:01:05 -0000, Ray Heindl <[email protected]>
    wrote:

    >I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    >expensive to replace, or is it because they're loaded differently, or have I just been lucky?

    I'm just guessing here, but the fact that the cone is stationary may mean it is loaded always at teh
    same area: the bottom.

    The cup, on the other hand, gets loaded round and round, so the fatigue is spread out over a
    larger area.
     
  9. Jobst Brandt

    Jobst Brandt Guest

    Dianne Feinstein writes:

    >> I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    >> expensive to replace, or is it because they're loaded differently, or have I just been lucky?

    > I'm just guessing here, but the fact that the cone is stationary may mean it is loaded always at
    > teh same area: the bottom.

    > The cup, on the other hand, gets loaded round and round, so the fatigue is spread out over a
    > larger area.

    I see, you never take wheels out of your bicycle or at least mark the axles so you can reinstall
    them oriented for shortest life.

    Good thinking!

    Jobst Brandt [email protected]
     
  10. Carl Fogel

    Carl Fogel Guest

    [email protected] wrote in message news:<[email protected]>...
    > Dianne Feinstein writes:
    >
    > >> I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    > >> expensive to replace, or is it because they're loaded differently, or have I just been lucky?
    >
    > > I'm just guessing here, but the fact that the cone is stationary may mean it is loaded always at
    > > teh same area: the bottom.
    >
    > > The cup, on the other hand, gets loaded round and round, so the fatigue is spread out over a
    > > larger area.
    >
    > I see, you never take wheels out of your bicycle or at least mark the axles so you can reinstall
    > them oriented for shortest life.
    >
    > Good thinking!
    >
    > Jobst Brandt

    Dear Jobst,

    If I lived in a place where goathead thorns didn't force me to fix flats and if I wasn't bad at
    maintaining wheels that I have to replace a drive-side spoke every month or two, I suspect that my
    wheels would rust into place on the frame.

    Dianne's suggestion about the cones facing asymmetric stress for long periods seems rather sensible,
    whatever the actual effect may be.

    I'm just jealous that she thought of it. Aren't you?

    Carl Fogel
     
  11. Jobst Brandt

    Jobst Brandt Guest

    Carl Fogel writes:

    >> Dianne Feinstein writes:

    >>>> I've seen spalled cones, but never the cups. Are the cups made tougher because they're more
    >>>> expensive to replace, or is it because they're loaded differently, or have I just been lucky?

    >>> I'm just guessing here, but the fact that the cone is stationary may mean it is loaded always at
    >>> teh same area: the bottom.

    >>> The cup, on the other hand, gets loaded round and round, so the fatigue is spread out over a
    >>> larger area.

    >> I see, you never take wheels out of your bicycle or at least mark the axles so you can reinstall
    >> them oriented for shortest life.

    >> Good thinking!

    > If I lived in a place where goathead thorns didn't force me to fix flats and if I wasn't bad at
    > maintaining wheels that I have to replace a drive-side spoke every month or two, I suspect that my
    > wheels would rust into place on the frame.

    > Dianne's suggestion about the cones facing asymmetric stress for long periods seems rather
    > sensible, whatever the actual effect may be.

    Well there are other reasons for taking wheels out of a bicycle such as tossing them in the back of
    a car to ride somewhere else than right around home. With the variety of great rides in California
    all year around, driving to a starting point a hundred miles away is not unusual. Even 20 miles to
    cross the freeway infested Santa Clara valley is a common event. Mt. Hamilton to Livermore and back
    loop being a classic 100 miler in this region.

    http://mthamilton.ucolick.org/hamcam/

    > I'm just jealous that she thought of it. Aren't you?

    I have considered it but my cones usually spall at least 3/4 of their circumference when they go
    anyway, and as I said, my wheels come out pretty often. That's why I thought of the scenario I
    mentioned above.

    Jobst Brandt [email protected]
     
Loading...
Thread Status:
Not open for further replies.
Loading...