Is my front hub about to fail? Please look at pics

Discussion in 'Cycling Equipment' started by Doug, May 14, 2003.

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  1. Doug

    Doug Guest

    Hey all,

    During a routine inspection, I noticed what look like fatigue lines in my Bullseye front hub.

    Lacing is 24 radial, Wheelsmith spokes, double butted, not sure of gauge. About 3000-4000 miles on
    it, 180 pound rider, Velocity Deep V rim, 700x23 tires @100 psi always.

    Pics at http://draizk.tripod.com/hub

    Note the bright lines stretching between the spoke holes in the flange. These lines are only on the
    outside of the flange. They do not stretch between all holes. On both sides, they stretch between 9
    holes. The lines are more visible on the left flange, skewer handle side.

    With 12 spokes per side, there are of course 12 spaces between spoke holes. So there are 3 spaces
    with no lines. Those 3 spaces are exactly 180 deg from each other around the wheel. ie, on the
    right side the 3 clean spaces are down, on the left the 3 clean spaces are up. If that helps
    determine anything.

    Please advise. Safety first and only. This thing will go if this is any indication.

    Beyond the issue of failure or not, what may have caused this? Normal fatigue that is expected? A
    single hard road hit? Too many cumulative hits? Too high spoke tension? The pitfalls of radial
    lacing? A weakness in this Bullseye hub? I had convinced myself this was a very good hub for radial
    lacing and was confident in it.

    Thanks, Doug
     
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  2. Call Roger Durham at Bullseye, same 800 number he has had for years (but I don't have it right
    here). The phone # was mentioned in a thread here a few months ago (search Google Groups?)

    I have several radial front wheels on Bullseye hubs, no problems. They are all for Moulton (17" tire
    OD), some are only 14 spokes (and high spoke tension), the wheels/hubs work fine.

    On Thu, 15 May 2003, Doug wrote:

    > Hey all,
    >
    > During a routine inspection, I noticed what look like fatigue lines in my Bullseye front hub.
    >
    > Lacing is 24 radial, Wheelsmith spokes, double butted, not sure of gauge. About 3000-4000 miles on
    > it, 180 pound rider, Velocity Deep V rim, 700x23 tires @100 psi always.
    >
    > Pics at http://draizk.tripod.com/hub
    >
    > Note the bright lines stretching between the spoke holes in the flange. These lines are only on
    > the outside of the flange. They do not stretch between all holes. On both sides, they stretch
    > between 9 holes. The lines are more visible on the left flange, skewer handle side.
    >
    > With 12 spokes per side, there are of course 12 spaces between spoke holes. So there are 3 spaces
    > with no lines. Those 3 spaces are exactly 180 deg from each other around the wheel. ie, on the
    > right side the 3 clean spaces are down, on the left the 3 clean spaces are up. If that helps
    > determine anything.
    >
    > Please advise. Safety first and only. This thing will go if this is any indication.
    >
    > Beyond the issue of failure or not, what may have caused this? Normal fatigue that is expected? A
    > single hard road hit? Too many cumulative hits? Too high spoke tension? The pitfalls of radial
    > lacing? A weakness in this Bullseye hub? I had convinced myself this was a very good hub for
    > radial lacing and was confident in it.
    >
    > Thanks, Doug
     
  3. Jobst Brandt

    Jobst Brandt Guest

    Doug who? writes:

    > During a routine inspection, I noticed what look like fatigue lines in my Bullseye front hub.

    > Lacing is 24 radial, Wheelsmith spokes, double butted, not sure of gauge. About 3000-4000 miles on
    > it, 180 pound rider, Velocity Deep V rim, 700x23 tires @100 psi always.

    http://draizk.tripod.com/hub

    > Note the bright lines stretching between the spoke holes in the flange. These lines are only on
    > the outside of the flange. They do not stretch between all holes. On both sides, they stretch
    > between 9 holes. The lines are more visible on the left flange, skewer handle side.

    I see no fatigue cracks, or for that matter any cracks in those pictures. All I see is a machining
    mark that left a slight smooth groove between flange holes. These look like substantial flanges that
    should withstand this load, assuming you don't weigh 300 lbs. That much load could give a cyclic
    load great enough to cause failure.

    > Please advise. Safety first and only. This thing will go if this is any indication.

    Radial spoking is not a good idea. It gains nothing in aerodynamics and saves a minuscule amount of
    weight because slightly shorter spokes can be used over tangential spoking. Spokes are so small in
    diameter with respect to their spacing that they do not draft one another, and they do this equally
    poorly as when laced conventionally with tangential spoking.

    > Beyond the issue of failure or not, what may have caused this? Normal fatigue that is expected? A
    > single hard road hit? Too many cumulative hits? Too high spoke tension? The pitfalls of radial
    > lacing? A weakness in this Bullseye hub? I had convinced myself this was a very good hub for
    > radial lacing and was confident in it.

    You'll need more resolution to prove that any fatigue damage is underway. What you seem to have
    there is not caused by fatigue.

    Jobst Brandt [email protected] Palo Alto CA
     
  4. Ron Hardin

    Ron Hardin Guest

    I've had rear hubs crack and nothing happens that doesn't happen when you break a spoke. It just
    goes out of true.

    The cause of the cracking was faux innertube tires, which were much harder than pneumatic and so
    transmit much more high-frequency road noise. In addition, the outer tires wear faster; though of
    course it doesn't matter if you get holes in them. And they're hell to get on and off over the
    fake tube.

    That was popular briefly probably around the late 70s, an idea that didn't work out. It saved you
    doing something easy (repairing a tube) and cost you hubs and screwdriver stabs getting the things
    on and off.
    --
    Ron Hardin [email protected]

    On the internet, nobody knows you're a jerk.
     
  5. Andy Dingley

    Andy Dingley Guest

    On Thu, 15 May 2003 04:16:37 GMT, [email protected] wrote:

    >Radial spoking is not a good idea.

    Why not ? "Looking good" isn't a crime ! If the flanges are adequate for it, and you're not trying
    for century-long lifetimes, then what's the problem ? We make much crazier design choices for the
    sake of "style"

    (and yes, I do have The Book)

    BTW - How long can hubs last ? I've a box of largely Campag 1950's bits and bobs, dry-stored since
    the '60's. There's no way I'd ride any of them, owing to surface corrosion.
     
  6. W K

    W K Guest

  7. Andy Dingley wrote:

    > On Thu, 15 May 2003 04:16:37 GMT, [email protected] wrote:
    >
    >> Radial spoking is not a good idea.
    >
    > Why not ? "Looking good" isn't a crime !

    But it doesn't look good, it looks like a stupid design.

    --
    Benjamin Lewis

    "Love is a snowmobile racing across the tundra and then suddenly it flips over, pinning you
    underneath. At night, the ice weasels come." --Matt Groening
     
  8. Doug

    Doug Guest

    >> During a routine inspection, I noticed what look like fatigue lines in my Bullseye front hub.
    >>
    >> Note the bright lines stretching between the spoke holes in the flange.
    >
    >I see no fatigue cracks, or for that matter any cracks in those

    Just so we're on the same page, I wasn't implying cracks, but rather lines. In this case possibly
    caused by metal stretch, presaging cracks. I've seen these lines before in applications where, say,
    overpressure in a vessel causes it to stretch, resulting in a shiny line on an otherwise dull
    surface at the stretch point. These lines look similar.
    >
    >You'll need more resolution to prove that any fatigue damage is underway. What you seem to have
    >there is not caused by fatigue.

    I'll try to get some better pics up.

    Thanks for the comments Jobst.

    Doug
     
  9. Doug

    Doug Guest

    >Call Roger Durham at Bullseye, same 800 number he has had for years (but I don't have it right
    >here). The phone # was mentioned in a thread here a few months ago (search Google Groups?)

    Thanks Doug, I found the number.

    Doug
     
  10. Jobst Brandt

    Jobst Brandt Guest

    Doug who? writes:

    >>> During a routine inspection, I noticed what look like fatigue lines in my Bullseye front hub.

    >>> Note the bright lines stretching between the spoke holes in the flange.

    >> I see no fatigue cracks, or for that matter any cracks in those

    > Just so we're on the same page, I wasn't implying cracks, but rather lines. In this case possibly
    > caused by metal stretch, presaging cracks. I've seen these lines before in applications where,
    > say, overpressure in a vessel causes it to stretch, resulting in a shiny line on an otherwise dull
    > surface at the stretch point. These lines look similar.

    I doubt it. There is nothing that would make a perfectly circular and smooth mark, centered on the
    flange hole circle develop as the feature detectable in the picture. Stretch marks are more random
    and are not circular. They also have roughness from upset material.

    >> You'll need more resolution to prove that any fatigue damage is underway. What you seem to have
    >> there is not caused by fatigue.

    > I'll try to get some better pics up.

    Looking forward to them.

    Jobst Brandt [email protected] Palo Alto CA
     
  11. On Thu, 15 May 2003 10:25:21 +0100, Andy Dingley wrote:

    > BTW - How long can hubs last ?

    Long time

    > I've a box of largely Campag 1950's bits and bobs, dry-stored since the '60's. There's no way I'd
    > ride any of them, owing to surface corrosion.

    Surface corrosion happens very fast at first. Every metal surface has an oxide layer. But after the
    part cools from the original forging/casting the oxide layer of an aluminum piece stays pretty much
    the same for years and years. I ride with one nearly 40-year-old seatpost, and another that is 34.
    I have no fear that one will suddenly crack on me, as scary as the results would be to contemplate.

    --

    David L. Johnson

    __o | What is objectionable, and what is dangerous about extremists is _`\(,_ | not that they are
    extreme, but that they are intolerant. (_)/ (_) | --Robert F. Kennedy
     
  12. John McGraw

    John McGraw Guest

    Doug <[email protected]> wrote in message news:<[email protected]>...
    > Hey all,
    >
    > During a routine inspection, I noticed what look like fatigue lines in my Bullseye front hub.
    >
    > Lacing is 24 radial, Wheelsmith spokes, double butted, not sure of gauge. About 3000-4000 miles on
    > it, 180 pound rider, Velocity Deep V rim, 700x23 tires @100 psi always.
    >
    > Pics at http://draizk.tripod.com/hub
    >
    > Note the bright lines stretching between the spoke holes in the flange. These lines are only on
    > the outside of the flange. They do not stretch between all holes. On both sides, they stretch
    > between 9 holes. The lines are more visible on the left flange, skewer handle side.
    >
    > With 12 spokes per side, there are of course 12 spaces between spoke holes. So there are 3 spaces
    > with no lines. Those 3 spaces are exactly 180 deg from each other around the wheel. ie, on the
    > right side the 3 clean spaces are down, on the left the 3 clean spaces are up. If that helps
    > determine anything.
    >
    > Please advise. Safety first and only. This thing will go if this is any indication.
    >
    > Beyond the issue of failure or not, what may have caused this? Normal fatigue that is expected? A
    > single hard road hit? Too many cumulative hits? Too high spoke tension? The pitfalls of radial
    > lacing? A weakness in this Bullseye hub? I had convinced myself this was a very good hub for
    > radial lacing and was confident in it.
    >
    > Thanks, Doug

    Hi Doug I'd bet my bottom $ that the circular indication in the photos is not a fatigue crack.
    Beginning or other wise. It could act as a stress riser that can eventually lead to cracking. But I
    doubt it. Having performed tens of thousands of penentrent, magnetic particle, & visual inspections,
    I know a crack when I see one. "I'm an ol' crack checker from way back" My guess is that it's an
    errant tool mark, or a layout line for the spoke hole circle. The vast majority of fatigue cracks
    have a certain look. A certain jaggedness. Even if they appear straight, close examination will
    reveal a slightly jagged, graininess. Also even if mostly straight, at some point they usually will
    dart in another direction. I count the perfectly radiused line as a straight line in this case.

    However if you're still not convinced, the best, most positive, way to determine if it is cracked,
    is to Non-Destructively test it w/ a Liquid Penetrant test. If you should decide to go that route,
    please E-mail me, & I'll be happy to advise you how to go about this for the least cost.

    But really you don't need to waste your $. John
     
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