Re-lace wheel the wrong way?

Discussion in 'Cycling Equipment' started by Morgan Fletcher, Apr 4, 2003.

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  1. I recently bought a new bicycle for my wife that was built with sew-ups. It's a NOS bike that's
    about 15 years old, and I want to keep the hubs but lace them to clinchers so I unlaced the sew-up
    rims. Last night I laced the hubs with fresh spokes and Mavic MA-3s. I laced the rear according to
    the steps in Jobst Brandt's book, like I always do.

    The problem is the elongation of the spoke holes caused by the first build has the spokes going in
    the wrong direction.

    Following the directions, I have the hub drive-side down. I keep the in-bound (spoke head facing
    outside) spokes in the holes as it was originally laced, and the first spoke goes to the higher hole
    on the rim, left of the valve stem. I repeat on the opposite side. Then when it comes time to wrap
    the hub so that the first spoke pulls away from valve stem hole, I see that the elongation marks on
    the hub are opposite from the way the spokes are oriented. In other words I would have to wrap the
    hub the opposite direction, so that the first spoke would angle across the imaginary line between
    valve stem hole and rim, if I were to match the existing spoke-hole elongation marks.

    Make sense?

    What to do?

    Not good at these sorts of conceptual puzzles,

    Morgan Fletcher Oakland, CA
     
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  2. Jobst Brandt

    Jobst Brandt Guest

    Morgan Fletcher writes:

    > I recently bought a new bicycle for my wife that was built with sew-ups. It's a NOS bike that's
    > about 15 years old, and I want to keep the hubs but lace them to clinchers so I unlaced the sew-up
    > rims. Last night I laced the hubs with fresh spokes and Mavic MA-3s. I laced the rear according to
    > the steps in Jobst Brandt's book, as I always do.

    > The problem is the elongation of the spoke holes caused by the first build has the spokes going in
    > the wrong direction.

    In another part of the book the reason for the preferred spoking pattern is explained and not
    claimed to be better than the one that your wheel had, at least not that one could measure. If you
    have not tightened the spokes yet, you should re-lace it the way the spokes were to avoid risking
    flange failure.

    If you have tightened the spokes, then new dimples have already been formed and cannot be undone, so
    just finish the job and hope for the best. If you are not extra heavy, and don't ride much rough
    stuff, the hub should last a long time. Before people thought about failure analysis, wheels were
    often re-spoked in a different pattern and no one thought about it when, once in a long while, a hub
    failed. It was usually attributed to some other effect. Besides, spoke failures were so common they
    masked most other failings.

    Jobst Brandt [email protected] Palo Alto CA
     
  3. In article <[email protected]>, Morgan Fletcher <[email protected]> wrote:
    >I recently bought a new bicycle for my wife that was built with sew-ups. It's a NOS bike that's
    >about 15 years old, and I want to keep the hubs but lace them to clinchers so I unlaced the sew-up
    >rims. Last night I laced the hubs with fresh spokes and Mavic MA-3s. I laced the rear according to
    >the steps in Jobst Brandt's book, like I always do.
    >
    >The problem is the elongation of the spoke holes caused by the first build has the spokes going in
    >the wrong direction.

    Relace it the way it was done before. This will increase the hub's odds of survival. Even
    laced "wrong" it won't have a significant effect on the finished product (esp. compared to a
    broken flange).

    --Paul
     
  4. lace it the opposite way. if you lace it the way it was originally, you'll keep moving the stress
    cycle graph towards the point of failure like this:

    http://technology.open.ac.uk/materials/mem/mem-ccf1.html

    if you lace it the other way, you effectively set the clock back to near zero because the stress is
    now oriented at 90 degrees to any cracks that may have nucleated. you should be able to
    conceptialize that if you look at how the cracks in this picure have grown in relation to the
    applied stress from each spoke and their relative orientations for each hole.

    ford.

    Morgan Fletcher wrote:
    > I recently bought a new bicycle for my wife that was built with sew-ups. It's a NOS bike that's
    > about 15 years old, and I want to keep the hubs but lace them to clinchers so I unlaced the sew-up
    > rims. Last night I laced the hubs with fresh spokes and Mavic MA-3s. I laced the rear according to
    > the steps in Jobst Brandt's book, like I always do.
    >
    > The problem is the elongation of the spoke holes caused by the first build has the spokes going in
    > the wrong direction.
    >
    > Following the directions, I have the hub drive-side down. I keep the in-bound (spoke head facing
    > outside) spokes in the holes as it was originally laced, and the first spoke goes to the higher
    > hole on the rim, left of the valve stem. I repeat on the opposite side. Then when it comes time to
    > wrap the hub so that the first spoke pulls away from valve stem hole, I see that the elongation
    > marks on the hub are opposite from the way the spokes are oriented. In other words I would have to
    > wrap the hub the opposite direction, so that the first spoke would angle across the imaginary line
    > between valve stem hole and rim, if I were to match the existing spoke-hole elongation marks.
    >
    > Make sense?
    >
    > What to do?
    >
    > Not good at these sorts of conceptual puzzles,
    >
    > Morgan Fletcher Oakland, CA
     
  5. Jobst Brandt

    Jobst Brandt Guest

    anonymous snipes:

    > Lace it the opposite way. If you lace it the way it was originally, you'll keep moving the stress
    > cycle graph towards the point of failure like this:

    http://technology.open.ac.uk/materials/mem/mem-ccf1.html

    > If you lace it the other way, you effectively set the clock back to near zero because the stress
    > is now oriented at 90 degrees to any cracks that may have nucleated. You should be able to
    > conceptialize that if you look at how the cracks in this picure have grown in relation to the
    > applied stress from each spoke and their relative orientations for each hole.

    The dimples caused by spokes occur when the wheel is first tensioned, trued and stress relieved.
    Failure comes later from metal fatigue. Lacing the spokes in the opposite direction will cause
    additional plastic flow that will increase the number of micro cracks from which separation can
    occur. Initial deformation and subsequent crack initiation, if any, does not go away by lacing
    spokes in the opposite direction, nor does the likelihood of failure. The 36-hole hub shown was
    laced cross-3. This should interest people who think fewer spokes, especially with radial spoking is
    advisable.

    I prefer to spoke as tangential as possible so that the forces are as far from radial as possible.
    This lessens the probability of flange failure and in my case, a Campagnolo hub like the on shown in
    the above URL has survived substantially more than 200,000 miles over the years. I am neither a
    lightweight nor do I restrict my riding to smooth paved roads. I think this is adequate proof that
    the failure shown is not a necessary outcome of long use.

    I saved two samples of the same kind of hub that look the same as the one in the picture. I saved
    these for people who want to know why they should build a wheel conservatively. It probably doesn't
    make much difference in my experience because people interested in unconventional wheels usually
    don't ride much or at least keep changing equipment to keep abreast of the latest fad.

    Jobst Brandt [email protected] Palo Alto CA
     
  6. bs writes-<< lace it the opposite way. if you lace it the way it was originally, you'll keep moving
    the stress cycle graph towards the point of failure like this:

    Wouldn't do this-lacing opposite asks for flange failures..

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  7. > Lacing the spokes in the opposite direction will cause additional plastic flow that will increase
    > the number of micro cracks from which separation can occur. Initial deformation and subsequent
    > crack initiation, if any, does not go away by lacing spokes in the opposite direction, nor does
    > the likelihood of failure.

    are you seriously trying to contend that crack growth is not affected by stress orientation?

    if so, you should publish a paper and share this spectaular phenomenon and turn the engineering
    world on it's head.

    ford
     
  8. G.Daniels

    G.Daniels Guest

    the 10 spd ridden here began reconditioning with a m.o. belgian rim and a 'three triangle' tiawan
    hub of soft aluminum. not knowing what i was doing( aphenomena that continues) i ran the spokes in a
    low torque mode and under heavy loads-the flange wore under spoke flex with elliptical spoke holes.
    almost through the hub. so, i 'laced', using the word loosely, backwards over fresh aluminum and
    continued on the road. no problems. frankly, the hub material seems so malleable or ductile, sorry
    jb, that fracture seeems possible only with several solid hits from a 11lb. hammer. what did reduce
    hub wear(besides more spoke torque) was cleaning and lubricating the spoke holes/spoke bends with
    wax/teflon lube-instead of cracks in the spokes and hub wear, the hub wear reducted 50% and spoke
    breakage(now with DT not generic)stopped! with wear becoming burnishing-the spokes moved rather than
    galled and cracked.
     
  9. Dave

    Dave Guest

    ford exploder <[email protected]> writes:

    > > Lacing the spokes in the opposite direction will cause additional plastic flow that will
    > > increase the number of micro cracks from which separation can occur. Initial deformation and
    > > subsequent crack initiation, if any, does not go away by lacing spokes in the opposite
    > > direction, nor does the likelihood of failure.
    >
    > are you seriously trying to contend that crack growth is not affected by stress orientation?
    >

    You are proposing that fatigue crack are definitely initiated after the hub is initially laced.
    What Jobst is saying (and the empirical evidence discussed in this forum seems to support) is that
    you are much more likely to generate cracks in the first place by relacing the opposite way.
    Apparently, hubs rarely fail this way except for radial lacing and relacing as described in this
    thread. Most structures never initiate fatigue cracks in the first place, and I suspect the same is
    true for hubs.

    Dave Korzekwa
     
  10. in article [email protected], [email protected] wrote:

    > The dimples caused by spokes occur when the wheel is first tensioned, trued and stress relieved.
    > Failure comes later from metal fatigue. Lacing the spokes in the opposite direction will cause
    > additional plastic flow that will increase the number of micro cracks from which separation can
    > occur. Initial deformation and subsequent crack initiation, if any, does not go away by lacing
    > spokes in the opposite direction, nor does the likelihood of failure.

    I have a relatively new bike (about 2500km) that came with a radially spoked front wheel (on a
    Shimano 105 hub). Would rebuilding it cross-3 at this stage be more likely to cause problems
    than cure any?

    -- Shane Stanley
     
  11. Jobst Brandt

    Jobst Brandt Guest

    Shane Stanley writes:

    >> The dimples caused by spokes occur when the wheel is first tensioned, trued and stress relieved.
    >> Failure comes later from metal fatigue. Lacing the spokes in the opposite direction will cause
    >> additional plastic flow that will increase the number of micro cracks from which separation can
    >> occur. Initial deformation and subsequent crack initiation, if any, does not go away by lacing
    >> spokes in the opposite direction, nor does the likelihood of failure.

    > I have a relatively new bike (about 2500km) that came with a radially spoked front wheel (on a
    > Shimano 105 hub). Would rebuilding it cross-3 at this stage be more likely to cause problems than
    > cure any?

    As I mentioned in an earlier response to this subject, lighter riders that do not blast down rough
    roads most likely won't have any failures. Some hubs are specifically designed to withstand radial
    spoking so that is also a consideration. No one blanket statement applies to all cases or even a
    few, but it is something to consider.

    Jobst Brandt [email protected] Palo Alto CA
     
  12. M Gagnon

    M Gagnon Guest

    <[email protected]> wrote:

    >
    > > Lace it the opposite way. If you lace it the way it was originally, you'll keep moving the
    > > stress cycle graph towards the point of failure like this:
    >
    > http://technology.open.ac.uk/materials/mem/mem-ccf1.html ... The dimples caused by spokes occur
    > when the wheel is first tensioned, trued and stress relieved. Failure comes later from metal
    > fatigue. ... The 36-hole hub shown was laced cross-3. This should interest people who think fewer
    > spokes, especially with radial spoking is advisable.
    >
    > I prefer to spoke as tangential as possible so that the forces are as far from radial as possible.
    > This lessens the probability of flange failure and in my case, a Campagnolo hub like the on shown
    > in the above URL has survived substantially more than 200,000 miles over the years.

    Michel Gagnon asks: One technical question. What if we were to push the design a little further?
    Would a 36-hole wheel laced cross-4 would be even stronger than a cross-3? I know it would be "past"
    the tangential alignment and that there might be problems in trying to get the spokes in the holes,
    but if it's possible to solve the problem (with a large flange, 1975-style, for example), what would
    be the results?

    Regards,

    Michel Gagnon
     
  13. Jobst Brandt

    Jobst Brandt Guest

    Michel Gagnon writes:

    >>> Lace it the opposite way. If you lace it the way it was originally, you'll keep moving the
    >>> stress cycle graph towards the point of failure like this:

    http://technology.open.ac.uk/materials/mem/mem-ccf1.html

    >> The dimples caused by spokes occur when the wheel is first tensioned, trued and stress relieved.
    >> Failure comes later from metal fatigue. ...The 36-hole hub shown was laced cross-3. This should
    >> interest people who think fewer spokes, especially with radial spoking is advisable.

    >> I prefer to spoke as tangential as possible so that the forces are as far from radial as
    >> possible. This lessens the probability of flange failure and in my case, a Campagnolo hub like
    >> the on shown in the above URL has survived substantially more than 200,000 miles over the years.

    > One technical question. What if we were to push the design a little further? Would a 36-hole wheel
    > laced cross-4 would be even stronger than a cross-3? I know it would be "past" the tangential
    > alignment and that there might be problems in trying to get the spokes in the holes, but if it's
    > possible to solve the problem (with a large flange, 1975-style, for example), what would be the
    > results?

    The maximum cross number is roughly INT(N/9) or x4 for a 36 spoke wheel. This doesn't work for the
    smallest front wheel flanges but it works well for the hub shown in the URL above. The result is
    that pairs of spokes in adjacent holes pull toward each other and that they do not pull outward on a
    bridge-like periphery of the flange. The periphery of the flange is not stressed in bending.

    Jobst Brandt [email protected] Palo Alto CA
     
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