Max side load of a 20 inch rim?

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

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" wrote in message
om...
"Ben" wrote in message
news:6OGzc.46610$Ds.46416@clgrps12...
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

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" wrote in message
om...
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" wrote in message
news:rpYzc.48217$Ds.46630@clgrps12...
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" wrote in message
om...
"Ben" wrote in message
news:6OGzc.46610$Ds.46416@clgrps12...
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

"Ben" wrote in message
news:7s0Ac.45932$eA.1307@clgrps13...
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

"Ben" wrote in message
news:7s0Ac.45932$eA.1307@clgrps13...
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

On Wed, 16 Jun 2004 18:37:55 GMT, Ben 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|
|/ \|

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.

Mark South wrote:

"Ben" wrote in message
news:7s0Ac.45932$eA.1307@clgrps13...

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

"Ben" wrote in message
news:7s0Ac.45932$eA.1307@clgrps13...
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