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Is it normal wheels go out of true after a fall?

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Is it normal wheels go out of true after a fall?

Old 09-08-22, 12:25 AM
  #26  
cyccommute 
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Originally Posted by Sonofamechanic View Post
Cyccommute—you definitely know your physics…but the reality is that most of us have been biking 30+ years…and when you take a spill or hit a particularly bad bump…well…the wheels often go out of true. They just do.
It’s not a frequent event. I’ve had lots and lots and lots of crashes for lots and lots of reasons…even ones that have knocked the handle bars out of place like Ev0lutionz describes…and have never had a wheel go out of true because of a crash. I’ve even experienced “going over the high side” on a jump when my hand slipped off the right bar and the wheel dug into the ground, levering me up and over the bike so that I was looking back up the hill (when I came to) that I had just come down. The front wheel was not tacoed nor bent even though it was the lever that launched me into the air.

An wheel can go out of true for a number of reasons with it resulting from crashing being way down the list of possible explanations. If you caught the wheel in a railroad or a drain gate, sure. But those are special cases.
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Old 09-08-22, 01:47 AM
  #27  
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Originally Posted by cyccommute View Post
What’s the fun in running away from having your head handed to you…again?
What do you mean I got my head handed to me? I thought you realized your mistake and we moved on after you admitted it? You're now saying you won? Here is the exact quote of you admitting your mistake. I thought I was being gracious. Next time you prefer for me to kick you a few times after you are down to make it sink in and ensure you're able to remember? What the hell??? Hello???

Originally Posted by cyccommute View Post
Decreasing speed 0.5mph below terminal speed compared to pulse braking to keep the average speed 20 mph lower than terminal…the pulse braking might result in slightly higher rim temperatures. It might not, however. It would depend on magnitude of the difference.
Yes, your rims do in fact deflect over 5mm side to side with only hand pressure. I asked you to go to your bike and try it. Did you try it? No you didn't. I know you didn't try it because if you did you wouldn't be talking. If you don't know metric units, take a ruler with you. Yes, bike wheels are in fact surprisingly flexible laterally. Yes, I know how to build wheels properly. I've seen you in the touring forum so you know I'm an expedition tourist: off road Mongolia Gobi Desert, Central Asia Silk Road, Burma, etc. The worst roads in the world with full expedition loads. I've been building wheels for a very long time. I worked in a bike shop during college. I don't mind if you question other stuff but please don't start with this ******** about wheel building. You can't build a better wheel than me. Just end it right there.

Yes, if your center of gravity is not in plane with the bike it is possible to have a sideways force on the wheel. But as I said in my previous post this would not be riding your bicycle properly. Do you actually ride like this? When you are riding straight, do you have your bike canted to one side and your body leaning to the other side? When you are cornering, are you doing some motocross style body dip where you throw your ass off the inside of the bike? Or are you one of those people who corner by leaning the bike over but keep their body upright? To whoever is reading this and is learning to ride a bike, don't do that. Always keep a straight tuck around a high speed corner. By the time you actually need these extremely niche bike leaning techniques for berm and off camber mountain bike turns, you're already too advanced to be reading this crap on Bike Forums.




Originally Posted by cyccommute View Post
The bike and rider would put far more lateral force on a wheel when cornering than would happen during a crash.
Let us refocus and come back to the point: my original response was to your claim above that the lateral force on a wheel during a turn is far more than the wheel bending force during a crash. Believe me, any lateral force you manage to moto-dip with your ass onto the wheel is not greater than the rim bending force in a crash. No matter how large your ass is and no matter how poor your riding technique is. You say in your other post that you've never bent a wheel during a crash? Good for you for being so lucky. I have, as have plenty of other people. Isn't it crazy that your personal anecdotal experience isn't the universal truth? Hard to accept I know.

When you have managed to bend a wheel purely by cornering too hard, then return here and report back in to us. In the meantime please stop with these patently wrong false-confidence statements.
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Old 09-08-22, 06:41 AM
  #28  
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Originally Posted by Inusuit View Post
Explain please. I have a stand to work on my bike but have turned it upside down to take off a wheel to fix a flat.
Shift to the small/small gears
Open brake is using rim brakes...if disks you don't have to...says cap'n obvious
loosen quick release or remove thru axle
Remove wheel
set bike on ground on non-drive side...sigh, why did I have to say that???
Replace tube or patch flat
Inflate tire
Put tire in dropouts with the chain on the gear with the fewest teeth...when you removed the wheel you shouldn't have touched the shifters
tighten skewer or thru axle
hold up rear end with one hand, shift a couple of gears with the other hand and using same hand pedal to move chain up a couple of gears
re-attach brake cable is mech rim brake
get on bike and ride easily while gently shifting to the gear you want
ride on
sigh...
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Old 09-08-22, 06:54 AM
  #29  
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One can cant one's bike over to one side and lean the other way and balance when going straight, thereby putting a strong lateral force on the wheel. Try it - its easy to do. In the same way, this can be done while turning. So it's possible to have lateral forces on wheels, and pretty strong ones. Do people do this in practice? I don't think that much. But it's completely possible to have lateral forces on wheels, even on straightaways.

Too, I think that in some circumstances one could put enough lateral force on a wheel to untrue it. Imagine catching some air and turning the wheel while airborne to compensate. When the turned wheel hit the ground it might put the wheel out of true.

But in this case, engineering, metaphysical and religious arguments are unnecessary. The wheels hit a bump, and there was a crash. The wheels are not true either because of the bump or because of the crash, or both. A Failure Mode Analysis is hardly needed here! True them and get back to riding!

On Edit: I just thought a little bit about how I ride and I think that I usually do ride with the bike (very) slightly canted to left. Dynamical analysis of bicycle stabilty is deucedly difficult (surprisingly so) but I hypothesize that most people ride with a slight tilt for stability sake. If so there's always some lateral force. What do you all think?

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Old 09-08-22, 07:00 AM
  #30  
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Originally Posted by Kai Winters View Post
Shift to the small/small gears
Open brake is using rim brakes...if disks you don't have to...says cap'n obvious
loosen quick release or remove thru axle
Remove wheel
set bike on ground on non-drive side...sigh, why did I have to say that???
Replace tube or patch flat
Inflate tire
Put tire in dropouts with the chain on the gear with the fewest teeth...when you removed the wheel you shouldn't have touched the shifters
tighten skewer or thru axle
hold up rear end with one hand, shift a couple of gears with the other hand and using same hand pedal to move chain up a couple of gears
re-attach brake cable is mech rim brake
get on bike and ride easily while gently shifting to the gear you want
ride on
sigh...
Okay, Cap'n Condescension. I've known how to remove a wheel and fix a flat for 50 years. Sigh... What you haven't explained is why you think it's wrong to place the bike upside down to do so.
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Old 09-08-22, 07:12 AM
  #31  
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Originally Posted by Kai Winters View Post
Shift to the small/small gears
Open brake is using rim brakes...if disks you don't have to...says cap'n obvious
loosen quick release or remove thru axle
Remove wheel
set bike on ground on non-drive side...sigh, why did I have to say that???
Replace tube or patch flat
Inflate tire
Put tire in dropouts with the chain on the gear with the fewest teeth...when you removed the wheel you shouldn't have touched the shifters
tighten skewer or thru axle
hold up rear end with one hand, shift a couple of gears with the other hand and using same hand pedal to move chain up a couple of gears
re-attach brake cable is mech rim brake
get on bike and ride easily while gently shifting to the gear you want
ride on
sigh...
Easier to just to flip the bike upside down and have two hands free.

Captain Obvious.

(sigh….)

Last edited by Kapusta; 09-08-22 at 07:19 AM.
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Old 09-08-22, 07:15 AM
  #32  
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Originally Posted by Inusuit View Post
Okay, Cap'n Condescension. I've known how to remove a wheel and fix a flat for 50 years. Sigh... What you haven't explained is why you think it's wrong to place the bike upside down to do so.
Because it is not and he knows it.
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Old 09-08-22, 08:17 AM
  #33  
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Originally Posted by cyccommute View Post
Gotta disagree. While it is true that a wheel is less strong in the lateral direction, it is still strong enough for most uses. The bike and rider would put far more lateral force on a wheel when cornering than would happen during a crash. Most of the force in a crash is going to be centered on the most massive part of the system which is the rider.

That’s assuming proper tension on the wheels, of course.
Lol, all of my wheels should be tacoed from cornering I guess.
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Old 09-08-22, 08:28 AM
  #34  
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"Is it normal wheels go out of true after a fall?"
There are no normals in a fall. If your wheel is out of true just fix it and enjoy the ride.
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Old 09-08-22, 08:35 AM
  #35  
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Theory vs experience….It wasn’t until Late 2000 that physicists finally documented how it was that a bumblebee could inconceivably move such massive weight with such tiny wings….of course that was neither here nor there to the bumblebee who had pollen to gather. So it is with those of us who ride…rims regularly go out of true in a sidewise fall and flipping a bike upside down to change a flat or lube a chain has no detrimental impact on the performance or durability of the bike, whatsoever. So theorize and opine all you want…we’ll keep riding, and fixing, in the meantime.
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Old 09-08-22, 09:07 AM
  #36  
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Originally Posted by Yan View Post
What do you mean I got my head handed to me? I thought you realized your mistake and we moved on after you admitted it? You're now saying you won? Here is the exact quote of you admitting your mistake. I thought I was being gracious. Next time you prefer for me to kick you a few times after you are down to make it sink in and ensure you're able to remember? What the hell??? Hello???
I edited my post to remove that comment. I shouldn’t have said it and I apologize.

On the other hand, I never admitted the mistake you think I made. That quote isn’t admitting anything other than your comparisons are not equal. I really don’t want to go back over that ground but when comparing equal conditions pulse braking results in cooler rims than drag braking. In some instances, pulse braking is even going to result in cooler rims when the conditions aren’t equal. The same can’t be said for drag braking unless the conditions are widely different.

Yes, your rims do in fact deflect over 5mm side to side with only hand pressure. I asked you to go to your bike and try it. Did you try it? No you didn't. I know you didn't try it because if you did you wouldn't be talking. If you don't know metric units, take a ruler with you. Yes, bike wheels are in fact surprisingly flexible laterally.
I’ve said that wheels are flexible laterally…that’s the whole point of bring up the lateral force, which you say doesn’t exist. However, when you flex the wheel by hand you are flexing it at the point where you are putting pressure on it. You aren’t flexing the entire rim out of plane. The spokes keep the part of the rim where there is no pressure straight. Leaning the bike over in a curve will not result the rim bending at the brake surface. Only the part of the wheel in contact with the ground will flex sideways.

I will point out that you were saying above that there is no lateral flex in the rim. Which is it? The bike has lateral flex or it doesn’t?

Yes, I know how to build wheels properly. I've seen you in the touring forum so you know I'm an expedition tourist: off road Mongolia Gobi Desert, Central Asia Silk Road, Burma, etc. The worst roads in the world with full expedition loads. I've been building wheels for a very long time. I worked in a bike shop during college. I don't mind if you question other stuff but please don't start with this ******** about wheel building. You can't build a better wheel than me. Just end it right there.
I’ve been building wheels for a long time as well. I know a lot about building them and even teach other people how to build them. You don’t know if I can build a better wheel than you just as I can’t know if you build a better wheel than I do. But I do know a lot about wheel building and wheel dynamics.

Yes, if your center of gravity is not in plane with the bike it is possible to have a sideways force on the wheel. But as I said in my previous post this would not be riding your bicycle properly.
It’s called cornering. I’m pretty sure that you corner from time to time which hangs the CG out of plane with the contact patch.

Do you actually ride like this? When you are riding straight, do you have your bike canted to one side and your body leaning to the other side? When you are cornering, are you doing some motocross style body dip where you throw your ass off the inside of the bike? Or are you one of those people who corner by leaning the bike over but keep their body upright?
When riding in a straight line, no I don’t cant the bike to one side or the other. If I’m pedaling out of the saddle, I throw the bike from one side to the other but my CG is generally vertical. When I corner, I lean into the corner, away from the contact patch. Now think about that. Where is the CG in that case? Gravity is pulling the CG down and the CG is out of plane with the contact patch. The vector force is angled through the CG but the normal force is still acting on the CG which is a long ways from the contact patch. The only thing keeping the CG from dropping to the ground is the friction of the tires and the lateral force they put on the wheels. This cantilevering of the CG is also what is causing the relatively weak rims to bend out of plane with the axle.

To whoever is reading this and is learning to ride a bike, don't do that. Always keep a straight tuck around a high speed corner. By the time you actually need these extremely niche bike leaning techniques for berm and off camber mountain bike turns, you're already too advanced to be reading this crap on Bike Forums.

Look at that picture again. Where is the CG in relation to the contact patch?

Let us refocus and come back to the point: my original response was to your claim above that the lateral force on a wheel during a turn is far more than the wheel bending force during a crash. Believe me, any lateral force you manage to moto-dip with your ass onto the wheel is not greater than the rim bending force in a crash.
Yes, let’s refocus. Let’s look at what happens in a slide out crash as an example. And I’ll use your picture for illustration.




Gravity is acting on the CG pulling it down. As the rider leans into the corner, the lateral force on the tires is pushing towards the CG. The lateral force is a fraction of the normal force but still enough to case some flexing of the rim out of the plane of the wheel. Now lets say the rider leans over further to the point where the friction on the tires no longer can hold the bike in the corner. The lateral force on the wheels eventually fails and the wheels slide out from under the rider.



When the friction fails the only force acting on the bike is the normal force and the CG goes into free fall (well, close enough). The lateral force on the wheels goes to zero and the wheels are no longer being bent out of plane. The CG eventually hits the ground but the force on the wheels is zero. There is no force on the wheels to “bend” them.

If the wheels happened to be trapped so that they can’t slide, bending the wheel would be possible but that’s different from sliding out on a corner.


No matter how large your ass is and no matter how poor your riding technique is.
I have been nothing but respectful towards you. I do not hurl insults nor attack you personally. I expect the same from you.


When you have managed to bend a wheel purely by cornering too hard, then return here and report back in to us. In the meantime please stop with these patently wrong false-confidence statements.
I won’t have to report back because it doesn’t happen. I can envision some instances where a wheel could be bent in a crash…wheel trapped in something, for example…but bending a wheel simply by “cornering too hard” is never going to bend a wheel that is properly built.
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Old 09-08-22, 09:11 AM
  #37  
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Originally Posted by cyccommute View Post
I won’t have to report back because it doesn’t happen.
…knock on wood.
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Old 09-08-22, 09:15 AM
  #38  
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Originally Posted by cyccommute View Post
I edited my post to remove that comment. I shouldn’t have said it and I apologize.

On the other hand, I never admitted the mistake you think I made. That quote isn’t admitting anything other than your comparisons are not equal. I really don’t want to go back over that ground but when comparing equal conditions pulse braking results in cooler rims than drag braking. In some instances, pulse braking is even going to result in cooler rims when the conditions aren’t equal. The same can’t be said for drag braking unless the conditions are widely different.



I’ve said that wheels are flexible laterally…that’s the whole point of bring up the lateral force, which you say doesn’t exist. However, when you flex the wheel by hand you are flexing it at the point where you are putting pressure on it. You aren’t flexing the entire rim out of plane. The spokes keep the part of the rim where there is no pressure straight. Leaning the bike over in a curve will not result the rim bending at the brake surface. Only the part of the wheel in contact with the ground will flex sideways.

I will point out that you were saying above that there is no lateral flex in the rim. Which is it? The bike has lateral flex or it doesn’t?



I’ve been building wheels for a long time as well. I know a lot about building them and even teach other people how to build them. You don’t know if I can build a better wheel than you just as I can’t know if you build a better wheel than I do. But I do know a lot about wheel building and wheel dynamics.



It’s called cornering. I’m pretty sure that you corner from time to time which hangs the CG out of plane with the contact patch.



When riding in a straight line, no I don’t cant the bike to one side or the other. If I’m pedaling out of the saddle, I throw the bike from one side to the other but my CG is generally vertical. When I corner, I lean into the corner, away from the contact patch. Now think about that. Where is the CG in that case? Gravity is pulling the CG down and the CG is out of plane with the contact patch. The vector force is angled through the CG but the normal force is still acting on the CG which is a long ways from the contact patch. The only thing keeping the CG from dropping to the ground is the friction of the tires and the lateral force they put on the wheels. This cantilevering of the CG is also what is causing the relatively weak rims to bend out of plane with the axle.



Look at that picture again. Where is the CG in relation to the contact patch?



Yes, let’s refocus. Let’s look at what happens in a slide out crash as an example. And I’ll use your picture for illustration.




Gravity is acting on the CG pulling it down. As the rider leans into the corner, the lateral force on the tires is pushing towards the CG. The lateral force is a fraction of the normal force but still enough to case some flexing of the rim out of the plane of the wheel. Now lets say the rider leans over further to the point where the friction on the tires no longer can hold the bike in the corner. The lateral force on the wheels eventually fails and the wheels slide out from under the rider.



When the friction fails the only force acting on the bike is the normal force and the CG goes into free fall (well, close enough). The lateral force on the wheels goes to zero and the wheels are no longer being bent out of plane. The CG eventually hits the ground but the force on the wheels is zero. There is no force on the wheels to “bend” them.

If the wheels happened to be trapped so that they can’t slide, bending the wheel would be possible but that’s different from sliding out on a corner.




I have been nothing but respectful towards you. I do not hurl insults nor attack you personally. I expect the same from you.




I won’t have to report back because it doesn’t happen. I can envision some instances where a wheel could be bent in a crash…wheel trapped in something, for example…but bending a wheel simply by “cornering too hard” is never going to bend a wheel that is properly built.
Oh freaking blah, blah, blah, you just said cornering is worse than a crash a bit ago.
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Old 09-08-22, 09:32 AM
  #39  
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I’m going to second Mr 66 on this one Cyccommute…the goal here is experienced, technical advice and while you have superb technical awareness, no cyclist worth his salt is going to say its “impossible” to taco a rim by heavy cornering….many of us have seen it happen. This forum needs the level of input you bring to a discussion, and to your credit you’ve done an admirable job of keeping your cool during the back and forth, maybe just slow your roll a bit on the whole “my theory trumps your experience” approach? I’d love to bike a century with you—I bet we’d talk the whole ride and both come away smarter.
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Old 09-08-22, 09:53 AM
  #40  
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I cannot remember the last time I have had to true a wheel and I ride a lot. Probably back in the aluminum rim stone age period of time was the last truing I needed. Crashing has never caused a wheel to go out of true for me.
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Old 09-08-22, 09:54 AM
  #41  
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Originally Posted by cyccommute View Post
I will point out that you were saying above that there is no lateral flex in the rim. Which is it? The bike has lateral flex or it doesn’t?
It is possible for the wheel to flex easily. However it does not flex in practice because there is no lateral force on it.

Originally Posted by cyccommute View Post
It’s called cornering. I’m pretty sure that you corner from time to time which hangs the CG out of plane with the contact patch. When I corner, I lean into the corner, away from the contact patch. Now think about that. Where is the CG in that case? Gravity is pulling the CG down and the CG is out of plane with the contact patch. The vector force is angled through the CG but the normal force is still acting on the CG which is a long ways from the contact patch. The only thing keeping the CG from dropping to the ground is the friction of the tires and the lateral force they put on the wheels. This cantilevering of the CG is also what is causing the relatively weak rims to bend out of plane with the axle.
???

When you are cornering the vector of force is traveling to the ground inline with the wheel. Here's an article from ACA teaching people how to ride a bike. They use the terminology "local gravity". In Figure 5 on the right you can see that the force vector is completely in line with the wheel whether you are riding straight or cornering. From the perspective of the wheel it cannot tell the difference.


https://www.adventurecycling.org/def...ring_Heine.pdf

Originally Posted by cyccommute View Post
Gravity is acting on the CG pulling it down. As the rider leans into the corner, the lateral force on the tires is pushing towards the CG. The lateral force is a fraction of the normal force but still enough to case some flexing of the rim out of the plane of the wheel. Now lets say the rider leans over further to the point where the friction on the tires no longer can hold the bike in the corner. The lateral force on the wheels eventually fails and the wheels slide out from under the rider.

The lateral force does not exist independently. It is only an on-paper mathematical component of the diagonal force vector. The diagonal force is the force which actually exists in reality (the so called "local gravity" in the ACA article). This force is in line with the wheel. The wheel does not experience any force that pulls it side to side. It only experiences a force that is in line with its plane. This force is perfectly capable of causing a slide out despite being diagonal to the ground.

Take a pencil, stand it upright on your desk and place your finger at its top to keep it upright. Now move your finger around so the pencil leans in different directions. Is the pencil experiencing any bending force? No! The pencil experiences only pure axial compression force no matter which way you lean it.

You may be confusing bending with buckling. Buckling is a completely different failure mode that has nothing to do with lateral forces.
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Old 09-08-22, 10:45 AM
  #42  
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Old 09-08-22, 11:57 AM
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Originally Posted by Crankycrank View Post
"Is it normal wheels go out of true after a fall?"
There are no normals in a fall. If your wheel is out of true just fix it and enjoy the ride.
Similar to Tolstoy's "All happy families are the same. Every unhappy family is unhappy in a different way." For bicycles, all happy rides are the same (at least as far as the chain doesn't break, the tires don't go flat, the wheels don't go out of true, etc.). But when something goes wrong, it's more or less unique (although perhaps foreseeable if the bike hasn't been maintained properly).
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Old 09-08-22, 08:02 PM
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If your method works for you...it works
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Old 09-09-22, 12:28 PM
  #45  
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Originally Posted by Yan View Post
It is possible for the wheel to flex easily. However it does not flex in practice because there is no lateral force on it.
There can be lateral forces on a wheel. You can generate them easily. On your bike, going in a straight line, cant your bike to the left while balancing by shifting your weight to the right. The center of graviity is over the contact point of the wheel, but the wheel is tilted left or right. I'm a big guy, and I suspect I could break a wheel with lateral force in this way.

Originally Posted by Yan View Post
... the force vector is completely in line with the wheel whether you are riding straight or cornering. From the perspective of the wheel it cannot tell the difference.
The force vector is directly over the contact point of the wheel on the ground. If the center point of the wheel (center of the hub) is collinear with that contact point and the effective cg, then there's no lateral force. But I suspect everybody, in every case, is canted a little left or a little right. So I suspect that there is almost always lateral force of some size on the wheel. I done this myself dozens if not hundreds of times. People have been doing this since 1901 (see pic)!

Originally Posted by Yan View Post
The lateral force does not exist independently. It is only an on-paper mathematical component of the diagonal force vector.
Forces exist, and lften are broken down into components. Your argument is that there is never a net lateral force on the rim. Sorry, that's wrong.

Originally Posted by Yan View Post

This force is in line with the wheel. The wheel does not experience any force that pulls it side to side. It only experiences a force that is in line with its plane. This force is perfectly capable of causing a slide out despite being diagonal to the ground.
Again, if the rider puts a torque on the frame (relative to axial direction, that is, the direct of travel, there is a lateral force

Originally Posted by Yan View Post
Take a pencil, stand it upright on your desk and place your finger at its top to keep it upright. Now move your finger around so the pencil leans in different directions. Is the pencil experiencing any bending force? No! The pencil experiences only pure axial compression force no matter which way you lean it.
If you took a machinist's square and you tried to balance it on its blade, there would be a lateral force on the blade when the square was nearly balanced. Your pencil is an idealized and overly constrained example. This reminds me of a joke: Q: "Why did the chicken cross the road?" A: (by a physicist) "Well, I have an answer, but it only applies to a perfectly spherical chicken in a vacuum." The pencil is a bit of a spherical chicken here.
​​​​​​​
Originally Posted by Yan View Post

You may be confusing bending with buckling. Buckling is a completely different failure mode that has nothing to do with lateral forces.
Not sure that I would agree. Interesting short paper on bicycle wheel failing. Going into "taco mode" is caused by spoke tension too high. I suspect that folks with very high spoke tension may be in a local energy minimum. In that case, adding lateral force might be enough to induce a taco. See buckling-and-collapse-of-the-bicycle-wheel. The taco transistion is called elastic buckling.

By the way, recall the OPs original question about untruing his wheel in a crash. All of the arguments so far seem to ignore the fact that in a crash, none of the forces have to be in line with anything: a crash is dynamic and hence by definition force may not be centered over a wheel.

Note the picture below (from "FANCY CYCLING. TRICK RIDING FOR AMATEURS' ISABEL MARKS. LONDON. SANDS & COMPANY, 1901.) The rider is on the left side of both wheels. To simplify, in straight travel, his CG IS over the contact point of the tire to the ground but CANNOT be over the center of the wheel hub. Therefore there is radial torque on the hub and of necessity there is lateral force on the wheel rim. If this rider had wanted to, he could lower his CG, grab the seat, and extend the bike out even further to his right, placing extreme lateral force on the hub.

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Old 09-09-22, 12:31 PM
  #46  
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WizardofBoz I agree with everything you said. Good analysis.
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Old 09-09-22, 01:31 PM
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Yan, my late father in law was trained in physics. Smartest guy I ever met. He mentioned to me that bicycle dynamics is REALLY hard to analyze. Since you are interested:

Here is a Scientific American article "The bicycle problem that nearly broke math".

There's a whole book on bicycle analysis. If I can find it I'll cite it.
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Old 09-10-22, 08:20 AM
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Originally Posted by Mr. 66 View Post
Oh freaking blah, blah, blah, you just said cornering is worse than a crash a bit ago.
And I don’t see anything in what I said in the quote that says otherwise. Cornering is harder on wheels than a crash but wheels don’t go out of true strictly due to cornering. If they did, we couldn’t ride bikes. Cornering can certainly contribute to a wheel going out of true because of the dynamics of the wheel and the changes in loading but, generally, you can do a whole lot of riding which involves a lot of cornering without the wheels going out of true.
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Old 09-10-22, 08:24 AM
  #49  
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Originally Posted by Sonofamechanic View Post
I’m going to second Mr 66 on this one Cyccommute…the goal here is experienced, technical advice and while you have superb technical awareness, no cyclist worth his salt is going to say its “impossible” to taco a rim by heavy cornering….many of us have seen it happen. This forum needs the level of input you bring to a discussion, and to your credit you’ve done an admirable job of keeping your cool during the back and forth, maybe just slow your roll a bit on the whole “my theory trumps your experience” approach? I’d love to bike a century with you—I bet we’d talk the whole ride and both come away smarter.
If a wheel were to taco just by heavy cornering, there is something else wrong with the wheel then the cornering.
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Old 09-10-22, 09:19 AM
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Originally Posted by Yan View Post
It is possible for the wheel to flex easily. However it does not flex in practice because there is no lateral force on it.
There is a lateral component to the force vector. That means there is a lateral force on the wheel.



???

When you are cornering the vector of force is traveling to the ground inline with the wheel. Here's an article from ACA teaching people how to ride a bike. They use the terminology "local gravity". In Figure 5 on the right you can see that the force vector is completely in line with the wheel whether you are riding straight or cornering. From the perspective of the wheel it cannot tell the difference.


https://www.adventurecycling.org/def...ring_Heine.pdf
You are misinterpreting the figures. Yes, the force vector travels in a straight line from the center of gravity to the contact patch but the vector labeled “local gravity” is the result of two straight vectors…gravitational force pulling the CG down and the centrifugal force acting on the contact patch to pull the contact patch around the corner. The centrifugal force is the lateral force on the wheel. By the way, while Heine has the proper label on the centrifugal, he has the wrong direction and the wrong location on that force. The direction of the force is towards the CG, not away from it.

The lateral force does not exist independently. It is only an on-paper mathematical component of the diagonal force vector. The diagonal force is the force which actually exists in reality (the so called "local gravity" in the ACA article). This force is in line with the wheel. The wheel does not experience any force that pulls it side to side. It only experiences a force that is in line with its plane. This force is perfectly capable of causing a slide out despite being diagonal to the ground.
No, it doesn’t exist independently but it does exist and it has an impact on the wheel as a lateral force. The location of the CG away from the contact patch makes the force vector act similarly to a lever. The force of gravity pulls down on the CG which cause the wheel to bend upward out of the “local gravity” vector at the contact patch.

A slide out is experienced when the angle of the “local gravity” vector becomes too small for the friction of the contact patch to hold onto the road. As the angle decreases (from 90° to something greater than 0°), the friction on the road becomes less until such time that the CG falls towards the ground and the centripetal force isn’t enough to overcome inertia. At some point the lateral force on the wheel is zero and the wheel will stop bending. Hitting the ground at this point..which is inevitable…means that there is no force on the wheels. What is the force that can cause the wheel to go out of true in such a crash?

Take a pencil, stand it upright on your desk and place your finger at its top to keep it upright. Now move your finger around so the pencil leans in different directions. Is the pencil experiencing any bending force? No! The pencil experiences only pure axial compression force no matter which way you lean it.
The pencil is far more rigid than a bicycle wheel (or spoke) but, yes, it would experience a bending force. The pencil is rigid enough so that the bending force is tiny but it is still there. Make the pencil thinner and the rigidity would decrease to the point of being able to detect the bending force. Since you are fond of food analogies, try the same experiment with a piece of dried spaghetti. Here, I’ll do it for you. (Please ignore the focus.). I attempted to keep the force on the spaghetti the same but it is difficult to do so. Let’s assume that the force is the same.

Vertical


10° to 15°



Roughly 45°



There is a very noticeable bend to the small, flexible rod.

Now in the other direction. This shape would be more along the lines of what the rim would see in a corner. The friction holds the end of the spaghetti (and the rim) in place. The CG acts as a lever to bend the end of the spaghetti (and the rim) upwards. The bend would be far less in a wheel because of the other spokes stabilizing the rim but it would still bend slightly upwards out of plane.


:



You may be confusing bending with buckling. Buckling is a completely different failure mode that has nothing to do with lateral forces.
Buckling could be caused by lateral forces but it would have other, underlying causes.
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