Max side load of a 20 inch rim?

Discussion in 'Recumbent bicycles' started by Ben, Jun 15, 2004.

  1. Ben

    Ben Guest

    I was wondering what the max load (side) is of a 20 inch
    wheel, for that matter the side load of a 24 and 26 would
    be good too.

    Ben
     
    Tags:


  2. Jeff Wills

    Jeff Wills Guest

    "Ben" <[email protected]> wrote in message news:<[email protected]>...
    > I was wondering what the max load (side) is of a 20 inch
    > wheel, for that matter the side load of a 24 and 26 would
    > be good too.
    >
    > Ben

    Excellent question. However, there's a lot more variables
    than just size. For instance: Rim width Rim cross-section
    Rim material Spoke tension Number of spokes Spoke bracing
    angle ... and a few more than I've probably missed.

    Jeff
     
  3. Ben

    Ben Guest

    Hummm, good point, but is there a starting point for say a
    standard BMX rim and one for a standard Mountain Bike rim?

    Please dont ask me what is standard... lets start with a
    Walmart cheapie rim and I will go from there.

    Ben

    "Jeff Wills" <[email protected]> wrote in message
    news:[email protected]...
    > "Ben" <[email protected]> wrote in message
    news:<[email protected]>...
    > > I was wondering what the max load (side) is of a 20 inch
    > > wheel, for that matter the side load of a 24 and 26
    > > would be good too.
    > >
    > > Ben
    >
    > Excellent question. However, there's a lot more variables
    > than just size. For instance: Rim width Rim cross-section
    > Rim material Spoke tension Number of spokes Spoke bracing
    > angle ... and a few more than I've probably missed.
    >
    > Jeff
     
  4. Jeff Wills

    Jeff Wills Guest

    Any starting point is irrelevant if you're just asking
    about the rim. A spoked wheel's strength is in the tension
    of the spokes.

    If you want resistance to side loads and only want to
    compare rims, wider is better, thicker is better, and
    aluminum is better. Larger diameter wheels will be weaker.
    Beyond that, you're on your own.

    Jeff

    "Ben" <[email protected]> wrote in message
    news:<[email protected]>...
    > Hummm, good point, but is there a starting point for say a
    > standard BMX rim and one for a standard Mountain Bike rim?
    >
    > Please dont ask me what is standard... lets start with a
    > Walmart cheapie rim and I will go from there.
    >
    > Ben
    >
    >
    > "Jeff Wills" <[email protected]> wrote in message
    > news:[email protected]...
    > > "Ben" <[email protected]> wrote in message
    > news:<[email protected]>...
    > > > I was wondering what the max load (side) is of a 20
    > > > inch wheel, for that matter the side load of a 24 and
    > > > 26 would be good too.
    > > >
    > > > Ben
    > >
    > > Excellent question. However, there's a lot more
    > > variables than just size. For instance: Rim width Rim
    > > cross-section Rim material Spoke tension Number of
    > > spokes Spoke bracing angle ... and a few more than I've
    > > probably missed.
    > >
    > > Jeff
     
  5. Ben

    Ben Guest

    I really must work on how I word things and be
    explicitly specific

    I am looking for a good guess (if not exact numbers) of the
    maximum side load a bike wheel (preferably a cheap 20" bmx
    wheel) can take before becoming a pretzel (i.e catastrophic
    failure and or but not including warping). This includes but
    is not limited to (ha-ha) nuts, washers, axel, axel
    bearings, bearing keepers, hub, spokes (likely 32 in total),
    spoke nipples (32 to match previous item), rim, rim rubber
    band to keep the nipples from the tube, tube (if used, if
    not strike last comments, preferably a standard tube not a
    shrader valve tube), and tire (preferably a slick as it is a
    road bike). One more thing, I will be using 14mm and above
    size axles before this deviates us from the current question
    leading us into many many debates on stuff other than the
    question at hand.

    What I am trying to do here is design a frame (trike) and on
    the rear axel (two wheels on this axel, maybe a bad choice
    of words here again 'on the rear weldment assembly, which
    are attached 2 axels') figure out the necessary strength of
    the rear weldment assembly. These wheels (on the rear
    weldment assembly) do not lean, they will be vertical at all
    times and should I hit a turn at a high rate of speed. I
    know approximately how many G's I generate on this said high
    rate of speed turn, I want to know how much the wheel will
    take before warping. I then will take this data and build
    the frame to take the side load the wheel can, using
    appropriate safety factors.

    Before I get a lecture on the theories on design and that I
    may be over my head in this, I am a experienced aircraft
    designer and have FEA and CFD tools to help me in this
    venture as well as experience in doing the calcs by hand.

    I am not trying to be smart here I just want to be specific
    so I can find out a resource of side loading capabilities of
    a bike wheel or how to calculate it without having to rig up
    a test and determine it my self.

    Ben

    "Jeff Wills" <[email protected]> wrote in message
    news:[email protected]...
    > Any starting point is irrelevant if you're just asking
    > about the rim. A spoked wheel's strength is in the tension
    > of the spokes.
    >
    > If you want resistance to side loads and only want to
    > compare rims, wider is better, thicker is better, and
    > aluminum is better. Larger diameter wheels will be weaker.
    > Beyond that, you're on your own.
    >
    > Jeff
    >
    >
    > "Ben" <[email protected]> wrote in message
    news:<[email protected]>...
    > > Hummm, good point, but is there a starting point for say
    > > a standard BMX
    rim
    > > and one for a standard Mountain Bike rim?
    > >
    > > Please dont ask me what is standard... lets start with a
    > > Walmart cheapie
    rim
    > > and I will go from there.
    > >
    > > Ben
    > >
    > >
    > > "Jeff Wills" <[email protected]> wrote in message
    > > news:[email protected]...
    > > > "Ben" <[email protected]> wrote in message
    > > news:<[email protected]>...
    > > > > I was wondering what the max load (side) is of a 20
    > > > > inch wheel, for
    that
    > > > > matter the side load of a 24 and 26 would be good
    > > > > too.
    > > > >
    > > > > Ben
    > > >
    > > > Excellent question. However, there's a lot more
    > > > variables than just
    size.
    > > > For instance: Rim width Rim cross-section Rim material
    > > > Spoke tension Number of spokes Spoke bracing angle ...
    > > > and a few more than I've probably missed.
    > > >
    > > > Jeff
     
  6. "Ben" <[email protected]> wrote in message
    news:[email protected]...
    > I really must work on how I word things and be explicitly
    > specific
    >
    > I am looking for a good guess (if not exact numbers) of
    > the maximum side load a bike wheel (preferably a cheap 20"
    > bmx wheel) can take before becoming a pretzel (i.e
    > catastrophic failure and or but not including warping).
    > ... I am not trying to be smart here I just want to be
    > specific so I can find out a resource of side loading
    > capabilities of a bike wheel or how to calculate it
    > without having to rig up a test and determine it my self.

    It's got to be easier to pick up a kid's/BMX bike at the
    dump Saturday morning, clamp the axle to something solid and
    load the thing to failure. Your test rig is just the
    something solid, a bathroom scale, and a tape measure.
    Because you don't really have any idea how it will fail
    (rim, spokes, axle, housing, etc.), you're wasting your time
    speculating. One bike gives you two wheels, and by the time
    you break them, you'll be a real world expert on lateral
    loading of trike tires.

    My guess is that your trike rear axle support will be stiffness-
    limited, and the structure you build to get decent, safe
    handling will be far stronger than you need to resist
    "catastrophic failure."

    free advice,

    Fred
     
  7. Mark South

    Mark South Guest

    "Ben" <[email protected]> wrote in message
    news:[email protected]...
    > I really must work on how I word things and be explicitly
    > specific
    >
    > I am looking for a good guess (if not exact numbers) of
    > the maximum side load a bike wheel (preferably a cheap 20"
    > bmx wheel) can take before becoming a pretzel (i.e
    > catastrophic failure and or but not including warping).
    > ... I am not trying to be smart here I just want to be
    > specific so I can find out a resource of side loading
    > capabilities of a bike wheel or how to calculate it
    > without having to rig up a test and determine it my self.

    For most wheels the correct spoke tension is slightly above
    100 kg force. Somewhat above this loading the rim cannot
    correctly support the loads and crinkles. If the load is
    uneven across spokes the spokes can pull through the hub
    flange. The spokes themselves do not break until
    considerably higher loadings are reached.

    See The Book for more detail.

    So: take your intended wheel, count the spokes and measure
    the spoke angle from flange to rim. Simple trig will show
    you how much tension there is to support the rim against a
    side load.

    I'd expect that a 48-spoke BMX wheel with a wide hub would
    withstand side loads at least as well as anything else
    commonly encountered in the bike world.
    --
    "Do stairs, stairs, and more stairs, wherever you can
    find them."
    - Jim Roberts in rec.backcountry
     
  8. Ian Smith

    Ian Smith Guest

    On Wed, 16 Jun 2004 18:37:55 GMT, Ben <[email protected]> wrote:

    > should I hit a turn at a high rate of speed. I know
    > approximately how many G's I generate on this said high
    > rate of speed turn, I want to know how much the wheel
    > will take before warping. I then will take this data and
    > build the frame to take the side load the wheel can,
    > using appropriate safety factors.

    Surely you're limitted by friction to a sufficiently low
    number that teh design of lateral strength is not
    particularly significant - ruggedness would be more of a
    criterion?

    That is, assuming you're not going so fast that you develop
    any aerodynamic down-force, and assuming you don't have
    tacky tyres (both reasonable assumptions, I think), you
    can't get more than your combined body & vehicle weight
    vertical force on a wheel (other than transients) and you
    won't get a coefficient of friction more than 1, so say,
    design it for 120kg transverse force (unless you're
    particularly heavy).

    I don't think transients will generate transverse loads,
    because I think the tyre will flex (in a roll-off-the-rim
    type way) when subject to transient transverse loads, and
    such a transient will not get to teh frame.

    regards, Ian SMith
    --
    |\ /| no .sig
    |o o|
    |/ \|
     
  9. Sticker Jim

    Sticker Jim Guest

    I live in Canada (Ontario) too so will use Cdn prices
    and all the parts are available from Toronto, to BC
    and Montreal.

    First, I use standard 20", 48 spoke BMX wheels with 14mm
    axles that can be bought anywhere from about $15 wholesale
    up to about $100. I don't know what the spoke tension is
    because I buy the rims already assembled, and I've never had
    a wheel fail, or heard of one of these wheels fail, on a
    trike yet. I undo the wheel, jam and bearing nuts and shift
    the axles over to one side as far as they can go. This is
    usually in the range of having about
    1.75" to 2" of axle sticking out past the bearing/jam nuts
    on one side. To secure the axles to the bottom of the king
    pins, I use plain old 3/4" ,ild steel tubing with 1/8"
    thick wall. I cut a piece about 1.25" long and weld it
    (both MIG and TIG) at the appropriate angle to the bottom
    of the king pin bolt. I take a 35/64" drill bit (I don't
    have a 14mm drill bit :)) and drill out the center to
    accept the 14mm axle. Just about a perfect fit. As for
    strength and wheel security/tightness:

    - my brother is 6'4" and weighs 265lbs. He rides my trikes
    all the time and the wheels are fine
    - a friend is 6'1", weighs 260lbs and he puts the trikes up
    on two wheels and rides them around like that just about
    daily. He says it's a "crowd pleaser" :)
    - I am 6'2", weigh ~235lbs and ride fast and hard most of
    the time. I have taken 90 degree road corners on narrow 2
    lane roads at ~45kph - no problems at all. I also ride the
    trikes around occasionally on 2 wheels, sometimes at
    speeds approaching 30kph. Again, no problems.
    - we all have ridden the trikes to relatively high speeds
    (approaching 75kph) and our roads and sidewalks are not
    always as smooth and crack/pothole free as they could be.

    While I have to watch the wheel's axle nuts to make sure
    they stay tight (I use red and blue Loctite), I have never
    had an axle housing stretch/deform on me, I have never had
    an axle bend or break. The 48 spoke 20s might flex
    1/4" when riding hard corners or up on two wheels. They're
    very tough it would seem. I never hear the spokes clicking
    or pinging and I would think that those kinds of noises
    would be evidence of rim deformation or wheel problems
    (not an engineer - so don't quote me on that). The only
    things I worry about are the 26" rear wheels. Again
    though, they are standard steel and aluminum 36 spoke rims
    that can be bought for around $35 and come already spoked
    and ready to use once a freewheel/cassette has been spun
    on. While people have commented on how much the rear wheel
    flexes while up on two wheels or during hard cornering,
    again, I have never had a failure and hear no spoke sounds
    that I would associate with problems. I have a small magnet-
    powered tail light that has the magnet mounted about 3/4"
    away from the light housing. When cornering hard at speed,
    the rear wheel definitely flexes enough for the magnet on
    the spokes to come in contact with the housing. I tried a
    27" wheel and it was definitely not strong enough for
    trike use with the standard narrow hub. My friend and I
    are going to machine some custom x-long 36h hubs and make
    a couple "triple 27"" race trikes.

    I don't know what your planned loading is going to be, but I
    have build enough trikes like this and put enough KM on them
    to have pretty much 100% confidence in the BMX wheels, the
    standard plain-Jane 26" wheels (36 hole) and the mild steel
    axle housings.

    Hope this helps. Post pics when it's done :)

    > I really must work on how I word things and be explicitly
    > specific
    >
    > I am looking for a good guess (if not exact numbers) of
    > the maximum side load a bike wheel (preferably a cheap 20"
    > bmx wheel) can take before becoming a pretzel (i.e
    > catastrophic failure and or but not including warping).
    > This includes but is not limited to (ha-ha) nuts, washers,
    > axel, axel bearings, bearing keepers, hub, spokes (likely
    > 32 in total), spoke nipples (32 to match previous item),
    > rim, rim rubber band to keep the nipples from the tube,
    > tube (if used, if not strike last comments, preferably a
    > standard tube not a shrader valve tube), and tire
    > (preferably
    a
    > slick as it is a road bike). One more thing, I will be
    > using 14mm and
    above
    > size axles before this deviates us from the current
    > question leading us
    into
    > many many debates on stuff other than the question
    > at hand.
    >
    > What I am trying to do here is design a frame (trike) and
    > on the rear axel (two wheels on this axel, maybe a bad
    > choice of words here again 'on the rear weldment
    > assembly, which are attached 2 axels') figure out the
    > necessary strength of the rear weldment assembly. These
    > wheels (on the
    rear
    > weldment assembly) do not lean, they will be vertical at
    > all times and should I hit a turn at a high rate of speed.
    > I know approximately how many G's I generate on this said
    > high rate of speed turn, I want to know how
    much
    > the wheel will take before warping. I then will take this
    > data and build
    the
    > frame to take the side load the wheel can, using
    > appropriate safety
    factors.
    >
    > Before I get a lecture on the theories on design and that
    > I may be over my head in this, I am a experienced aircraft
    > designer and have FEA and CFD tools to help me in this
    > venture as well as experience in doing the calcs
    by
    > hand.
    >
    > I am not trying to be smart here I just want to be
    > specific so I can find out a resource of side loading
    > capabilities of a bike wheel or how to calculate it
    > without having to rig up a test and determine it my self.
     
  10. Tom Sherman

    Tom Sherman Guest

    Mark South wrote:

    > "Ben" <[email protected]> wrote in message
    > news:[email protected]...
    >
    >>I really must work on how I word things and be explicitly
    >>specific
    >>
    >>I am looking for a good guess (if not exact numbers) of
    >>the maximum side load a bike wheel (preferably a cheap 20"
    >>bmx wheel) can take before becoming a pretzel (i.e
    >>catastrophic failure and or but not including warping).
    >>... I am not trying to be smart here I just want to be
    >>specific so I can find out a resource of side loading
    >>capabilities of a bike wheel or how to calculate it
    >>without having to rig up a test and determine it my self.
    >
    >
    > For most wheels the correct spoke tension is slightly
    > above 100 kg force. Somewhat above this loading the rim
    > cannot correctly support the loads and crinkles. If the
    > load is uneven across spokes the spokes can pull through
    > the hub flange. The spokes themselves do not break until
    > considerably higher loadings are reached.
    >
    > See The Book for more detail.
    >
    > So: take your intended wheel, count the spokes and measure
    > the spoke angle from flange to rim. Simple trig will show
    > you how much tension there is to support the rim against a
    > side load.
    >
    > I'd expect that a 48-spoke BMX wheel with a wide hub would
    > withstand side loads at least as well as anything else
    > commonly encountered in the bike world.

    The author of "The Book" has a well known preference for ISO
    622-mm size Mavic MA-2 36-spoke rims with double butted
    spokes. I would suspect that a smaller diameter, wide, heavy
    duty rim (e.g. ISO 406-mm Sun Rhyno-Lite or Velocity Taipan)
    could withstand higher spoke tension before exhibiting a
    "potato chip" failure.

    Another approach would be to copy what works. Established
    trike builders such as Greenspeed use wheels such as I have
    mentioned above with good results. Unless you are attempting
    to achieve minimum weight, refinement through analysis and
    testing is not needed. The heavier stronger wheel will of
    course provide a larger factor of safety for occasional
    extreme dynamic loading that may occur.

    --
    Tom Sherman – Quad City Area
     
  11. Jeff Wills

    Jeff Wills Guest

    Ian Smith <[email protected]> wrote in message news:<[email protected]>...
    > On Wed, 16 Jun 2004 18:37:55 GMT, Ben
    > <[email protected]> wrote:
    >
    > > should I hit a turn at a high rate of speed. I know
    > > approximately how many G's I generate on this said high
    > > rate of speed turn, I want to know how much the wheel
    > > will take before warping. I then will take this data
    > > and build the frame to take the side load the wheel
    > > can, using appropriate safety factors.
    >
    > Surely you're limitted by friction to a sufficiently low
    > number that teh design of lateral strength is not
    > particularly significant - ruggedness would be more of a
    > criterion?
    >

    Well, I've seen Electrathon cars slide sideways around flat
    corners. Since they're using 20" bicycle wheels (both spoked
    and plastic "mag"), are heavier, and have lower centers of
    gravity than HPV's, I think they're putting greater sideways
    stress on the wheels. Conventional spoked wheels are fine.

    Ben, you're asking for quantifiable numbers for lateral
    strength. To my knowledge, this data doesn't exist. Also,
    there's *no* reason for it to exist, because bicycle wheels
    are typically not loaded in that direction. Lateral strength
    is a non-issue in the bicycle world.

    Also, in my experience with HPV trikes, you'll find that
    many will go up on two wheels at high cornering speeds. Most
    HPV trike wheels are capable of taking this stress.

    Jeff Wills
     
  12. Jack Davis

    Jack Davis Guest

    "Ben" <[email protected]> wrote in message
    news:[email protected]...
    > I really must work on how I word things and be explicitly
    > specific
    >
    > I am looking for a good guess (if not exact numbers) of
    > the maximum side load a bike wheel (preferably a cheap 20"
    > bmx wheel) can take before becoming a pretzel (i.e
    > catastrophic failure and or but not including warping).
    > This includes but is not limited to (ha-ha) nuts, washers,
    > axel, axel bearings, bearing keepers, hub, spokes (likely
    > 32 in total), spoke nipples (32 to match previous item),
    > rim, rim rubber band to keep the nipples from the tube,
    > tube (if used, if not strike last comments, preferably a
    > standard tube not a shrader valve tube), and tire
    > (preferably
    a
    > slick as it is a road bike). One more thing, I will be
    > using 14mm and
    above
    > size axles before this deviates us from the current
    > question leading us
    into
    > many many debates on stuff other than the question
    > at hand.
    >
    > What I am trying to do here is design a frame (trike) and
    > on the rear axel (two wheels on this axel, maybe a bad
    > choice of words here again 'on the rear weldment
    > assembly, which are attached 2 axels') figure out the
    > necessary strength of the rear weldment assembly. These
    > wheels (on the
    rear
    > weldment assembly) do not lean, they will be vertical at
    > all times and should I hit a turn at a high rate of speed.
    > I know approximately how many G's I generate on this said
    > high rate of speed turn, I want to know how
    much
    > the wheel will take before warping. I then will take this
    > data and build
    the
    > frame to take the side load the wheel can, using
    > appropriate safety
    factors.
    >
    > Before I get a lecture on the theories on design and that
    > I may be over my head in this, I am a experienced aircraft
    > designer and have FEA and CFD tools to help me in this
    > venture as well as experience in doing the calcs
    by
    > hand.
    >
    > I am not trying to be smart here I just want to be
    > specific so I can find out a resource of side loading
    > capabilities of a bike wheel or how to calculate it
    > without having to rig up a test and determine it my self.
    >
    > Ben
    >

    Ben,

    Have you considered asking the companies that make the
    wheels?

    Just a thought....

    jd
     
  13. lukeevans

    lukeevans New Member

    Joined:
    Mar 22, 2013
    Messages:
    8
    Likes Received:
    0
    Hi, sorry for bringing this old thread alive, but I'm looking at making a four wheel recumbent load carrier and have no idea how to work out how much lateral load a wheel can take. I'm assuming that a bmx wheel will be able to do it, but as it is said that through using simple trig an esitmate can be made, I would like to know that method.

    Im guessing that you draw triangles and your saying that the side load coming in should not be greater than the tension in the spokes?

    Mark says refer to the book but I'v looked in bicycle science, and The bicycle Wheel but neither spell it out (for somebody like me) how to approximate how much lateral force the spoke wheel can take.

    Cheers

    Luke
     
  14. blazingpedals

    blazingpedals New Member

    Joined:
    Oct 18, 2004
    Messages:
    394
    Likes Received:
    3
    From what I can read, it looks like nobody knew the answer back then, either.
     
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