I just got to share this with you....

Discussion in 'Cycling Equipment' started by Kevin Rook, Jun 15, 2003.

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  1. Kevin Rook

    Kevin Rook Guest

    While sitting under a brideg, waiting out a severe thunderstorm on this morning's ride, I had a
    conversation with some fellow cyclists about (what else) other rides we have been on. When I
    mentioned a couple I know that have hit 60MPH on a down hill while riding their tandem this one
    fellow piped up with "Their wheels aren't rated for that kind of speed!" Say what?!?! I have never
    heard of a speed rating for a wheel. He proceeded to inform that at all wheels have a maximum speed
    rating and it's based on a rating for the hub and the rim that it's laced to and it's all dependent
    on the rider's weight and the maximum speed that the can 'safely' obtain. Again I say, Say what?!?!
    He then started quoting all these formulas for calculating the load on a wheel based on all these
    different factor and while it didn't make a lot of sense to me I am used to feeling that way when
    talk gets technical. When he then quoted an "article from two months ago in Bicycling Magazine" I
    was pretty confident that he was spreading a load of (in the words of Peter C) "bugle oil" but I
    thought I get some opinions from the learned members of wreck.tech.

    What say you?

    Kevin
     
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  2. Kevin Rook <[email protected]> wrote in news:[email protected]:

    > While sitting under a brideg, waiting out a severe thunderstorm on this morning's ride, I had a
    > conversation with some fellow cyclists about (what else) other rides we have been on. When I
    > mentioned a couple I know that have hit 60MPH on a down hill while riding their tandem this one
    > fellow piped up with "Their wheels aren't rated for that kind of speed!" Say what?!?! I have never
    > heard of a speed rating for a wheel. He proceeded to inform that at all wheels have a maximum
    > speed rating and it's based on a rating for the hub and the rim that it's laced to and it's all
    > dependent on the rider's weight and the maximum speed that the can 'safely' obtain. Again I say,
    > Say what?!?! He then started quoting all these formulas for calculating the load on a wheel based
    > on all these different factor and while it didn't make a lot of sense to me I am used to feeling
    > that way when talk gets technical. When he then quoted an "article from two months ago in
    > Bicycling Magazine" I was pretty confident that he was spreading a load of (in
    the
    > words of Peter C) "bugle oil" but I thought I get some opinions from
    the
    > learned members of wreck.tech.
    >
    > What say you?
    >
    > Kevin

    That sounds pretty retarded to me. I've heard of hubs and rims having maximum load (weight) ratings,
    but never a speed rating. Then again, I could just be ignorant; I often am.

    - Boyd S.
     
  3. Jim Price

    Jim Price Guest

    Kevin Rook wrote:

    > What say you?

    Every single component on your bicycle _could_ be given a "speed rating" (though some might be a
    little silly). Bicycle manufacturers don't as a rule give out this kind of information, for a
    number of reasons. Here's a simple example to work out what the maximum rotational speed you should
    subject a set of ballbearings to - put in the dimensions of the contact areas of the bearings in
    your wheel hubs:

    http://www.wmberg.com/Tools/BrgSpd.html

    You should find that the results translate to very high speeds.

    Your car tyres will have a speed rating on them - again, bicycle tyres tend not to.

    As for rims and spokes, their "speed ratings" will depend on a lot of things including your weight
    and the type of terrain you are riding across. This would produce more information than the average
    purchaser would want to deal with, so again you will probably never see it in a brochure.

    Someone somewhere designed the bicycle you ride. If they did so using sound engineering priciples,
    then they will know how fast you can ride safely, but the lawyers in the marketing department will
    not want that information put out, so you'll get a few warranty clauses like "does not cover
    competion use" or "not warrantied for riders over 100Kg". These clauses may bear some relation to
    the specifications that the engineers were told to design the bike to.

    --
    Jim Price

    http://www.jimprice.dsl.pipex.com

    Conscientious objection is hard work in an economic war.
     
  4. On Sun, 15 Jun 2003 17:04:14 +0000, Kevin Rook wrote:

    > one fellow piped up with "Their wheels aren't rated for that kind of speed!" Say what?!?! I have
    > never heard of a speed rating for a wheel. He proceeded to inform that at all wheels have a
    > maximum speed rating and it's based on a rating for the hub and the rim that it's laced to and
    > it's all dependent on the rider's weight and the maximum speed that the can 'safely' obtain.

    Horse manure.

    > Again I say, Say what?!?! He then started quoting all these formulas for calculating the load on a
    >wheel based on all these different factor

    It is a common tactic to bolster BS arguments with formulas. Said formulas do not, apparently, have
    to have anything to do with the question at hand.

    Mere speed along will not be a problem to the wheel until that speed gets very, very high. Sure,
    that tandem might have a problem in a panic stop from 60 mph, but you have to hope your friends
    would not let it get to that speed unless they had a good long view ahead.

    > and while it didn't make a lot of sense to me I am used to feeling that way when talk gets
    >technical. When he then quoted an "article from two months ago in Bicycling Magazine"

    Well, _that_ is the final word in technical expertise.

    --

    David L. Johnson

    __o | And what if you track down these men and kill them, what if you _`\(,_ | killed all of us?
    From every corner of Europe, hundreds, (_)/ (_) | thousands would rise up to take our places.
    Even Nazis can't kill that fast. -- Paul Henreid (Casablanca).
     
  5. Why does your wheel care what speed it's going? In what way are the wheel components (aside from the
    tire) stressed differently at 10 miles per hour vs 50 miles per hour. Even the tires shouldn't have
    issues at speed in the manner that a car or motorcycle does, since heat buildup isn't a factor
    (sorry, but the human engine just cannot propel a bicycle, either on the flats or uphills, at speeds
    where the tire is going to suffer serious heat buildup! And when you are going really really fast,
    it's not because you're applying outrageous rotational forces to your wheel and tire.).

    As for the bearings, sorry, but bicycle components simply aren't rotating all that quickly, so the
    idea of burning a bearing out isn't going to happen due to speed, although lack of lubrication will
    cause eventual failure at any reasonable speed.

    --Mike-- Chain Reaction Bicycles http://www.ChainReactionBicycles.com

    "Kevin Rook" <[email protected]> wrote in message news:[email protected]...
    > While sitting under a brideg, waiting out a severe thunderstorm on this morning's ride, I had a
    > conversation with some fellow cyclists about (what else) other rides we have been on. When I
    > mentioned a couple I know that have hit 60MPH on a down hill while riding their tandem this one
    > fellow piped up with "Their wheels aren't rated for that kind of speed!" Say what?!?! I have never
    > heard of a speed rating for a wheel. He proceeded to inform that at all wheels have a maximum
    > speed rating and it's based on a rating for the hub and the rim that it's laced to and it's all
    > dependent on the rider's weight and the maximum speed that the can 'safely' obtain. Again I say,
    > Say what?!?! He then started quoting all these formulas for calculating the load on a wheel based
    > on all these different factor and while it didn't make a lot of sense to me I am used to feeling
    > that way when talk gets technical. When he then quoted an "article from two months ago in
    > Bicycling Magazine" I was pretty confident that he was spreading a load of (in the words of Peter
    > C) "bugle oil" but I thought I get some opinions from the learned members of wreck.tech.
    >
    > What say you?
    >
    > Kevin
     
  6. Kevin Rook writes with some snippage-<< When I mentioned a couple I know that have hit 60MPH on a
    down hill while riding their tandem this one fellow piped up with "Their wheels aren't rated for
    that kind of speed!" Say what?!?! >><BR><BR>

    He is right but he forgot to add a '1' to his equation-not rated for above 160mph...

    Peter Chisholm Vecchio's Bicicletteria 1833 Pearl St. Boulder, CO, 80302
    (303)440-3535 http://www.vecchios.com "Ruote convenzionali costruite eccezionalmente bene"
     
  7. Ns>

    Ns> Guest

    I would only worry if I didn't have Z rated tires on them...:)

    NS
     
  8. Jay Beattie

    Jay Beattie Guest

    "Kevin Rook" <[email protected]> wrote in message news:[email protected]...
    > While sitting under a brideg, waiting out a severe thunderstorm on
    this
    > morning's ride, I had a conversation with some fellow cyclists about (what else) other rides we
    > have been on. When I mentioned a couple I know that have hit 60MPH on a down hill while riding
    > their tandem this one fellow piped up with "Their wheels aren't rated for that kind of speed!" Say
    > what?!?! I have never heard of a speed rating for a wheel. He proceeded to inform that at all
    > wheels have a maximum speed rating and it's based on a rating for the hub and the rim that it's
    > laced to and it's all dependent on the rider's weight and the maximum speed that the can 'safely'
    > obtain. Again I say, Say what?!?! He
    then
    > started quoting all these formulas for calculating the load on a wheel based on all these
    > different factor and while it didn't make a lot of sense to me I am used to feeling that way when
    > talk gets technical. When he then quoted an "article from two months ago in Bicycling Magazine" I
    > was pretty confident that he was spreading a load of (in
    the
    > words of Peter C) "bugle oil" but I thought I get some opinions from
    the
    > learned members of wreck.tech.

    I cancelled my Bicycling subscription a year ago, but it still keeps coming -- and the last issue
    restated with unquestioned authority the myth that a pound off your wheels is worth two off your
    frame, as well as a few other wrong chestnuts. I cannot believe that anyone would cite to that
    magazine as authority for anything -- except maybe as the latest word on whether zebra-striped
    shorts can be worn after Labor Day.

    BTW, the Burley trailer has a speed limit (something ridiculously low like 15mph), but I am sure
    that is a stability-liability issue and not based on the potential for high-speed wheel failures. --
    Jay Beattie.
     
  9. Andresmuro

    Andresmuro Guest

    Jay wrote:

    >I cancelled my Bicycling subscription a year ago

    Clearly, a case of sublimation of "Style Man" envy.

    Andres
     
  10. On Mon, 16 Jun 2003 05:16:40 GMT, "Mike Jacoubowsky" <[email protected]> wrote:

    >Why does your wheel care what speed it's going? In what way are the wheel components (aside from
    >the tire) stressed differently at 10 miles per hour vs 50 miles per hour.

    Bearings, obviously, and of course with the weight of the rim and tire rotating so fast the spokes
    will have a slight extra load due to centrifugal force.. and the spokes will be going through
    load/unload cycles 5 times faster.

    Personally, I doubt the first 2 are even measurable on good components, let alone significant, and
    the last one is probably not a real problem either. But they're still differences.

    Jasper
     
  11. Kevin Rook

    Kevin Rook Guest

    Jasper Janssen wrote:

    > On Mon, 16 Jun 2003 05:16:40 GMT, "Mike Jacoubowsky" <[email protected]> wrote:
    >
    > >Why does your wheel care what speed it's going? In what way are the wheel components (aside from
    > >the tire) stressed differently at 10 miles per hour vs 50 miles per hour.
    >
    > Bearings, obviously, and of course with the weight of the rim and tire rotating so fast the spokes
    > will have a slight extra load due to centrifugal force.. and the spokes will be going through
    > load/unload cycles 5 times faster.
    >
    > Personally, I doubt the first 2 are even measurable on good components, let alone significant, and
    > the last one is probably not a real problem either. But they're still differences.
    >
    > Jasper

    I think this is where the guy was going with his explanation of why bicycles wheels 'shouldn't' go
    that fast. He said something about the weight of the rider and the rotational speed of the wheel
    being the factors.

    ....'course he also said that he saw a squirrel run into a guy's front wheel while in an 18mph pace
    line. The end result (according to the guy under the bridge now) was a front wheel with ALL the
    spokes broken and the guy who had been riding the bike doing THREE cartwheels down the road with the
    bike still attached to the rider's feet.

    So did anybody besides TGUTB (the guy under the bridge) see the article in Bicycling? It was
    probably some time this year (if it exists at all).

    Kevin
     
  12. AndresMuro <[email protected]> wrote:
    > Jay wrote:

    > >I cancelled my Bicycling subscription a year ago

    > Clearly, a case of sublimation of "Style Man" envy.

    Style Man is the best part of Bicycling magazine. He is funny, and he can't be taken too seriously,
    and he doesn't propagate myths like "an ounce on the wheel is worth two ...," unlike the rest of the
    magazine. In fact, Style Man's advice may have a better percentage of accuracy than most of the rest
    of the magazine.
     
  13. Tim McNamara

    Tim McNamara Guest

    In article <[email protected]>, Jasper Janssen <[email protected]> wrote:

    > On Mon, 16 Jun 2003 05:16:40 GMT, "Mike Jacoubowsky" <[email protected]> wrote:
    >
    > >Why does your wheel care what speed it's going? In what way are the wheel components (aside from
    > >the tire) stressed differently at 10 miles per hour vs 50 miles per hour.
    >
    > Bearings, obviously, and of course with the weight of the rim and tire rotating so fast the spokes
    > will have a slight extra load due to centrifugal force.. and the spokes will be going through
    > load/unload cycles 5 times faster.

    Considering that ball bearings routinely survive speeds of 100,000 RPM and more in many
    applications, it seems impossible for a bike rider to spin the wheel so fast that the bearings would
    be affected. Guesstimating that a standard 700C wheel has a circumference of about
    6.8 feet, that's about 650 RPM at 50 miles per hour, if I've done my math right.

    In a properly tensioned 32 spoke wheel, the spokes are tensioned to, what, roughly 100-120 kg of
    force, depending on the rim. Some rims can allow higher spoke tension than others. The "centrifugal"
    force will not add to this tension because the rim can't expand in major diameter as it rotates
    faster. I'll give you points for making a claim I've never heard anyone else make, though.

    The spokes don't care about the time interval between load, just about the number of loads. In a
    properly stress-relieved wheel without structurally damaged spokes, cycles to failure is a very high
    number (given that one poster to this newsgroup has more than 200,000 miles on a set of spokes; I've
    got several rear wheels with >10,000 to 15,000 miles on each with no spoke failures.)

    > Personally, I doubt the first 2 are even measurable on good components, let alone significant, and
    > the last one is probably not a real problem either. But they're still differences.

    I would agree with you that all these are insignificant, even nonexistent concerns.
     
  14. Dr. Dave

    Dr. Dave Guest

    Tim McNamara wrote:
    >
    > In a properly tensioned 32 spoke wheel, the spokes are tensioned to, what, roughly 100-120 kg of
    > force, depending on the rim. Some rims can allow higher spoke tension than others. The
    > "centrifugal" force will not add to this tension because the rim can't expand in major diameter as
    > it rotates faster.

    This simply is not true. The rim material will expand under hoop force load (in an amount determined
    by the Young's modulus of the material). Granted, at the rotational speeds we are discussing these
    effects will be negligible and will probably cause tire failure long before spoke or rim failure.

    >
    > The spokes don't care about the time interval between load, just about the number of loads.

    This assumes that there are no resonant phenomena involved. These are, of course, very frequency
    sensitive.

    In a properly stress-relieved wheel without
    > structurally damaged spokes, cycles to failure is a very high number (given that one poster to
    > this newsgroup has more than 200,000 miles on a set of spokes; I've got several rear wheels with
    > >10,000 to 15,000 miles on each with no spoke failures.)
    >
    >
    >
    >
    > I would agree with you that all these are insignificant, even nonexistent concerns.

    Agreed.
     
  15. Mark Janeba

    Mark Janeba Guest

    Tim McNamara wrote:
    > Considering that ball bearings routinely survive speeds of 100,000 RPM and more in many
    > applications, it seems impossible for a bike rider to spin the wheel so fast that the bearings
    > would be affected. Guesstimating that a standard 700C wheel has a circumference of about
    > 6.8 feet, that's about 650 RPM at 50 miles per hour, if I've done my math right.

    Looks about correct. A 27" wheel at 1 revolution per *second* is 4.8 miles per hour. (7.7 kph for
    our non-american readers).

    > In a properly tensioned 32 spoke wheel, the spokes are tensioned to, what, roughly 100-120 kg
    > of force, depending on the rim. Some rims can allow higher spoke tension than others. The
    > "centrifugal" force will not add to this tension because the rim can't expand in major diameter
    > as it rotates faster. I'll give you points for making a claim I've never heard anyone else
    > make, though.

    While we're having fun here, how about an amusing thought experiment: Suppose Superman or Steve
    Austin (the mechanical cyborg guy) or some such were to ride a bike to absurd speeds. Let's leave
    out sudden accelerations for now. At what speed would a typical bike fail, and in what manner?

    Melting tires sounds like a stronger candidate than wheels flying apart from centrifugal "force" or
    bearings overheating. (Isn't the motor-paced record near or above 150 mph now?) Remember without the
    motorized pacing fairing, the tire contact patch would be stressed much more to provide enough
    forward thrust to overcome wind resistance.

    (Hoping this thread can be amusing longer than the "A fundamental flaw with bikes/cycles" thread was
    before degenerating into a flame war about top-posting.)

    Regards,
    --
    Mark Janeba remove antispam phrase in address to reply
     
  16. DiabloScott

    DiabloScott New Member

    Joined:
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    The answer is obvious; Superman's integrated headset would disintegrate.
    How's that for amusing?
     
  17. On Mon, 16 Jun 2003 21:58:13 -0500, Tim McNamara <[email protected]> wrote:
    > Jasper Janssen <[email protected]> wrote:

    >> Bearings, obviously, and of course with the weight of the rim and tire rotating so fast the
    >> spokes will have a slight extra load due to centrifugal force.. and the spokes will be going
    >> through load/unload cycles 5 times faster.
    >
    >In a properly tensioned 32 spoke wheel, the spokes are tensioned to, what, roughly 100-120 kg
    >of force, depending on the rim. Some rims can allow higher spoke tension than others. The
    >"centrifugal" force will not add to this tension because the rim can't expand in major diameter
    >as it rotates faster. I'll give you points for making a claim I've never heard anyone else
    >make, though.

    It can't expand, no, but that doesn't mean it can't contribute to load. As a thought experiment,
    imagine a spoke tensioned to 1000 Newtons or so prestress between two solid bars that are unmovable
    farther than <spoke
    length> towards each other, ie, take four bricksized hunks'o'metal, and
    arrange appropriately into a rectangle. Now I lock down the bottom bar of metal to the floor, and
    using a pulley and a weight I apply 1000 Newtons towards the top on the top metal block. Now the
    spoke is under 2000 Newtons tension, not still 1000.

    As a second thought experiment, hang a rock or hunk'o'metal on the end of a string, and start
    spinning it from your hand. It'll eventually spin so fast that it and the rope are nearly in an
    horizontal plane. The only way that can happen is if there is an outwards force acting on the rock,
    even though it can't move any further because it's held by the rope.

    I suspect that in the case of the spoke and centrifugal force, it'll work out to a kilo or so of
    extra tension at most.

    Jasper
     
  18. Hedberg

    Hedberg Guest

    On Tue, 17 Jun 2003 20:45:20 GMT, Jasper Janssen <[email protected]> wrote:

    [...]
    >
    >As a second thought experiment, hang a rock or hunk'o'metal on the end of a string, and start
    >spinning it from your hand. It'll eventually spin so fast that it and the rope are nearly in an
    >horizontal plane. The only way that can happen is if there is an outwards force acting on the rock,
    >even though it can't move any further because it's held by the rope.
    [...]

    Just a minor quibble:

    All the force in this example is exerted on the string inward -- there is no outward force acting on
    the rock. The tendency of the rock to want to go outward is called inertia. The "centripetal" force
    is what overcomes the inertia and causes the rock to accelerate (i.e. change direction). Strictly
    speaking, there is no such thing as "centrifugal" force.

    Harold
     
  19. Dr. Dave

    Dr. Dave Guest

    Hedberg wrote:
    > On Tue, 17 Jun 2003 20:45:20 GMT, Jasper Janssen <[email protected]> wrote:
    >
    > [...]
    >
    >>As a second thought experiment, hang a rock or hunk'o'metal on the end of a string, and start
    >>spinning it from your hand. It'll eventually spin so fast that it and the rope are nearly in an
    >>horizontal plane. The only way that can happen is if there is an outwards force acting on the
    >>rock, even though it can't move any further because it's held by the rope.
    >
    > [...]
    >
    > Just a minor quibble:
    >
    > All the force in this example is exerted on the string inward -- there is no outward force acting
    > on the rock. The tendency of the rock to want to go outward is called inertia. The "centripetal"
    > force is what overcomes the inertia and causes the rock to accelerate (i.e. change direction).
    > Strictly speaking, there is no such thing as "centrifugal" force.
    >
    > Harold

    Just a minor couple of quibbles:

    If all of the force in this example is exerted on the string inward, then the string would move
    inward. This is not the case because the radial forces on the string are balanced. The rock exerts
    an outward force on the string and the hand exerts the inward force on the string. The outward force
    on the string is what is known as the centrifugal force. It is present due to the mass (inertia) of
    the rock coupled with the acceleration that causes it move in a circle.

    The rock does not want to move outward. It wants to continue motion in a straight line (tangent to
    the circle of motion) Just release the string while swinging it to verify this. It is necessary to
    apply the inward radial (centripetal) force via the string to make the rock move in a circle rather
    than a straight line. There is no tendance of the rock to want to move outward.
     
  20. Tim McNamara

    Tim McNamara Guest

    In article <[email protected]>, Jasper Janssen <[email protected]> wrote:

    > On Mon, 16 Jun 2003 21:58:13 -0500, Tim McNamara <[email protected]> wrote:
    > > Jasper Janssen <[email protected]> wrote:
    >
    > >> Bearings, obviously, and of course with the weight of the rim and tire rotating so fast the
    > >> spokes will have a slight extra load due to centrifugal force.. and the spokes will be going
    > >> through load/unload cycles 5 times faster.
    > >
    > >In a properly tensioned 32 spoke wheel, the spokes are tensioned to, what, roughly 100-120 kg of
    > >force, depending on the rim. Some rims can allow higher spoke tension than others. The
    > >"centrifugal" force will not add to this tension because the rim can't expand in major diameter
    > >as it rotates faster. I'll give you points for making a claim I've never heard anyone else make,
    > >though.
    >
    > It can't expand, no, but that doesn't mean it can't contribute to load. As a thought experiment,
    > imagine a spoke tensioned to 1000 Newtons or so prestress between two solid bars that are
    > unmovable farther than <spoke length> towards each other, ie, take four bricksized hunks'o'metal,
    > and arrange appropriately into a rectangle. Now I lock down the bottom bar of metal to the floor,
    > and using a pulley and a weight I apply 1000 Newtons towards the top on the top metal block. Now
    > the spoke is under 2000 Newtons tension, not still 1000.

    Not an engineer here. So bear with me.

    A rim weighs, what, 400 grams. Imagine it spinning in space, all by itself. How fast does it have to
    spin before it expands along the major diameter from centrifugal force, which would require the the
    metal of the rim to stretch? 1,000,000 rpm? More?

    Now, with an elastic and heavy item, such as pizza dough, you can easily see this happening. But an
    aluminum rim is a light and relatively inelastic structure. It doesn't stretch under rotation like
    pizza dough does, therefore the major diameter doesn't increase, and therefore it contributes no
    load to the spokes from centrifugal force. My contention is that the rim's tensile strength is such
    that at any realistic speed, it contributes nothing to spoke tension load.
     
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