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spokes appear weirdly curved in sprint-finish photo

Old 08-22-15, 03:38 PM
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Originally Posted by YWoodman
So...yes, the poor schmuck is trying to jut the bicycle underneath him out in front of him so as to hit the finish line earlier than he otherwise would, if not for the jutting action. This makes it appear as if he is trying to transplant the saddle into his gut. It is, of course, based on the same notion as the track runner who learns his chest forward in order to break the tape a bit sooner than he would without the lean.

Of course, they are NOT AT ALL the same thing. The runner's lean is sensible and works. This is because the finish is, by rule, only official once the athletes chest has crossed the line...and because the chest is a part of the runner's body and that body can be leaned forward, i.e., extended into the future from the waist.

It does NOT, however, work with bicycles. And it is amazing to see these idiots actually trying. See, the bicycle is in motion, just like your automobile...rolling along

There exists no force, attached to the vehicle, than can cause it to jump forward. It cannot extend itself from itself. It can only move faster via moving its wheels faster.

A cyclist can do to nothing to improve his position except pedal. This is as absolute as the soundest laws of physics. Pushing a bicycle forward, while attached to it, is 100% impossible.

That riders so often attempt it is nothing short of displaying their incredible ignorance and unthinking stupidity to everyone. Not to mention the complete morons their coaches, trainers and loved-ones must be to have said nothing sensible enough to them to stop this wholly cartoonish finish-line spectacle. It amounts to nothing more than a fine example of the superstition that drives, still, a great deal of human behavior.


...
The levity lies in the fact that, because they go through a pushing motion, riders only end up pushing themselves backward.
It certainly does work for cyclists, which is why the technique is used in the case of very close finishes. To the extent that the rider pushes himself backward he must by Newton's Law of 'equal and opposite reaction' simultaneously be pushing the bicycle forward. The speed of the center of gravity of the bike+rider will not be changed by this action, but for a very short time the rider can move his own mass backward relative to the bike and so for that moment he moves slower and the bike moves faster. The result is that the front wheel of the bike can cross the finish line just a bit earlier than it would if the rider stayed in his normal position on the bike.

The opposite effect can frequently be observed in a tight paceline when the grade increases and riders stand up on the pedals. Even though they continue to exert at least as much force on the pedals, the riders directly behind will notice that their bike momentarily slows down as they move their mass forward relative to the bike and therefore cause the bike to move backward relative to themselves.
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Old 08-22-15, 03:40 PM
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Originally Posted by YWoodman
Yes, I see that the thread is ancient...but, you know, it's all new to me.



It does NOT, however, work with bicycles. And it is amazing to see these idiots actually trying. See, the bicycle is in motion, just like your automobile...rolling along

There exists no force, attached to the vehicle, than can cause it to jump forward. It cannot extend itself from itself. It can only move faster via moving its wheels faster.

A cyclist can do to nothing to improve his position except pedal. This is as absolute as the soundest laws of physics. Pushing a bicycle forward, while attached to it, is 100% impossible.....
It's a good thing that none of the team members from back when I sponsored teams ever heard from you. Of course, though you assertively claim that riders who throw their bike forward are 100% wasting their time, I assert that you are 100% wrong on the issue and need to read up on "Conservation of Momentum".

The skater example I linked is a nice example. If they were on a moving platform (say a rail car going 50mph) they would move apart the same way. The centerline between them would travel the same speed, but the one pushed forward would arrive earlier than if she stayed close to her partner. Likewise with the bike.

The bicycle and rider are one moving unit for the entire approach to the finish line, but the position of the two elements bicycle and rider relative to each other can change. Since a bicycle weighs about 1/10th the rider, he can throw it forward gaining speed for it (for a moment) while losing 1/10th of the gain for himself. After the wheel crosses the finish line he can assume the original configuration which will reestablish the original speed (less loss to drag).

So timed right, he definitely can gain a few inches through this technique, which is well established, and why skilled riders use the technique in dead heats.


BTW- if bicycle race finishes were based on the rider's nose, this technique would be counterproductive. The rider would wish to pull the bike pack and bring his head forward, but because of the weight ratio the benefit would be minimal.

Edit - Prathman must have pushed his keyboard away as he was finishing his post, thereby beating me by a a minute or so.
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Old 08-22-15, 10:10 PM
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Amusingly, the slit camera was used in the late 19th century to make images of the sun that highlighted different chemical elements.

In this case the camera has the very useful property of having no parallax, so there's no dispute as to who came in 2nd, 3rd, etc.
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Old 08-23-15, 04:10 AM
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Originally Posted by FBinNY

Edit - Prathman must have pushed his keyboard away as he was finishing his post, thereby beating me by a a minute or so.
!
And I am a distant third, so I won't even bother trying
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Old 08-23-15, 04:12 AM
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Originally Posted by YWoodman
It does NOT, however, work with bicycles. .
Race much ?
Not a first rant to be proud of.

Physics & momentum.
https://zonalandeducation.com/mstm/ph...mSummary6.html
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Old 08-23-15, 05:54 AM
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The riders have reached time warp speed, that's all
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Old 08-23-15, 06:05 AM
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Originally Posted by YWoodman
Yes, I see that the thread is ancient...but, you know, it's all new to me.

So...yes, the poor schmuck is trying to jut the bicycle underneath him out in front of him so as to hit the finish line earlier than he otherwise would, if not for the jutting action. This makes it appear as if he is trying to transplant the saddle into his gut. It is, of course, based on the same notion as the track runner who learns his chest forward in order to break the tape a bit sooner than he would without the lean.

Of course, they are NOT AT ALL the same thing. The runner's lean is sensible and works. This is because the finish is, by rule, only official once the athletes chest has crossed the line...and because the chest is a part of the runner's body and that body can be leaned forward, i.e., extended into the future from the waist.

It does NOT, however, work with bicycles. And it is amazing to see these idiots actually trying. See, the bicycle is in motion, just like your automobile...rolling along

There exists no force, attached to the vehicle, than can cause it to jump forward. It cannot extend itself from itself. It can only move faster via moving its wheels faster.

A cyclist can do to nothing to improve his position except pedal. This is as absolute as the soundest laws of physics. Pushing a bicycle forward, while attached to it, is 100% impossible.

That riders so often attempt it is nothing short of displaying their incredible ignorance and unthinking stupidity to everyone. Not to mention the complete morons their coaches, trainers and loved-ones must be to have said nothing sensible enough to them to stop this wholly cartoonish finish-line spectacle. It amounts to nothing more than a fine example of the superstition that drives, still, a great deal of human behavior.

And in the middle of all the modern equipment that the pros have now...all the engineering and bleeding edge tech that has gone into their machines and training. And the incredible vast majority of persons involved in the sport simply can't help themselves from the numb-skull belief that a bicycle in motion could monkey push itself forward via any method other than increasing the pressure on the pedals that rotate the chain that drive the wheel that are its velocity.

The levity lies in the fact that, because they go through a pushing motion, riders only end up pushing themselves backward. They give themselves the appearance of stomaching their seats. From their point of view, however, like the rider on the train who doesn't sense that he is moving and gets the feeling that the station is moving as the train pulls away from it.

From the poor dumb cyclist's perspective, while it is he who is actually moving backward, his eyes tell his fabulously insufficient brains that the bicycle is moving forward. No dude! The bike isn't moving further forward, you are moving further back.
Entertaining post
I suppose gravity does not exist either and the other laws of physics are mere suggestions
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Old 08-23-15, 11:26 AM
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Clues for Ywoodmen: 1. The positions of the leading edge of the front tires determines the winner, not the positions of the center of mass. 2. Rather than using a reference frame fixed to the bicycle, use one fixed to the center of mass for the bike and rider combination.

There it is, everything you need to understand physical reality.
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Old 08-24-15, 12:48 AM
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In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.
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Old 08-24-15, 12:56 AM
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In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.

Newtons law does not apply. The force must be equal and opposite. The force of the rider does not equal the force of the bicycle. The rider is an entirely separate force, that, is subordinate to--existent within--the inertial frame of the bicycle.

For Newton's law to apply, both forces must exist within the same inertial frame. If the rider, for example, tosses a tennis ball up into the air as he is riding, that ball travels forward with him at the same velocity at which the cycle is carrying them...so, the ball will appear to go straight up and straight down relative to the rider or cycle, but relative to the stationary road the ball has traveled a distance forward. So too, when the rider pushes as the handle-bars, he is acting within the bicycle's inertial frame, it may then appear to him that he has pushed the cycle forward while actually pushing himself backward...but, the bicycle hasn't altered it's velocity not even one little bit.
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Old 08-24-15, 01:10 AM
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In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.

No, the 'conservation of momentum' does not apply to the push of the cyclist upon the bicycle. This is because both exist in the same inertial frame. Think of being in free fall with a ball, a bowling ball, you must push at it with more force than that which is required to move the ball a free fall speed. You would need the assistance of an extra-terminal-velocity force to push the ball any fast downward than it is already being pulled.

Now if you had a ball while riding on your bicycle, you can apply enough throwing force to hurl it outside your bicycle's mph inertial frame. But, without that much force, if you simply toss it straight up, it travels forward inside the inertial frame of the cycle. And this is what's happening when you push forward at the handle-bars, the force is entirely existent within the cycle's inertial frame and is in no way sufficient enough to move the bicycle forward anymore quickly than the bicycle is already moving.

To do this, you'd have to get a good push from behind. If you were moving at 30mph, you'd need an auto to meet your inertial frame by bumping your rear wheel at a speed greater than 30mph. Then you'd experience a jerk forward...note than when you push at the handle bars in a race, no forward jerk exists--the cycle doesn't break momentum.

Also, one cannot pull at the handlebars and slow a bicycle. All than can happen is that the front wheel lifts off the ground, but the velocity will not slow. This is like checking your math, if the reciprocal operation is impossible, then the initial operation couldn't be possible.
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Old 08-24-15, 01:13 AM
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In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.

Any forward push that you may believe is occurring is purely an illusion. I don't suppose that you also believe that it's possible to slow a bicycle by pulling on the handlebars? No, of course not. If the one operation is impossible then the other couldn't possible be.
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Old 08-24-15, 02:49 AM
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Originally Posted by YWoodman
In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.

Any forward push that you may believe is occurring is purely an illusion. I don't suppose that you also believe that it's possible to slow a bicycle by pulling on the handlebars? No, of course not. If the one operation is impossible then the other couldn't possible be.
Have it your way. I'm not invested in what you or anyone wishes to believe. I responded the first time to correct your misconceptions for the sake of anyone reading the thread. Now, I'll spare my fingers by taking George Carlin's advice and moving on.

However, I'll leave you with a parting thought. Consider what happens when a hand grenade is tossed at the enemy and explodes in the air, short of the target. The same rules that determine that outcome apply to a rider and bike "busting" just short of the finish line.

Have a good day.
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Old 08-24-15, 04:38 AM
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Originally Posted by YWoodman
In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.
Instead of reinventing physics, you should try it for yourself and see first hand.
Easiest to see the effect when doing a trackstand, or rolling at just 1-2 mph.

Same effect can be seen on a skateboard. By moving body weight, you can get the skateboard to move back and forth a little bit.

Every Action has an Equal and Opposite Reaction - This is the third of Sir Issac Newton's laws of physics

https://www.qrg.northwestern.edu/proj...-opposite.html
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Old 08-24-15, 09:18 AM
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Originally Posted by YWoodman
In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous. . . .
I can hear your feet stomping.

Originally Posted by YWoodman
. . . Newtons law does not apply. . . .
Because you say so.
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Old 08-24-15, 09:35 AM
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Originally Posted by YWoodman
In exactly the same way as you cannot push a car forward by pushing at the steering wheels, you cannot push a bicycle forward by pushing at the handle-bars. Period. All notions to the contrary are erroneous.

Any forward push that you may believe is occurring is purely an illusion. I don't suppose that you also believe that it's possible to slow a bicycle by pulling on the handlebars? No, of course not. If the one operation is impossible then the other couldn't possible be.
Suppose we are riding side by side, evenly matched, and the winner is the person whose right hand crosses the finish line first. As we approach the finish line, you confidently keep your hands on the bars. I remove my right hand from the bar and extend it forward to one foot forward of the bars. I have beaten you by almost one foot. Not a full foot, because the mass of my hand moving forward (relative to my center of mass) caused the rest of me (body and bike) to move rearward (relative to my COM). But this effect is proportional to the masses, my hand's mass is tiny compared to the mass of the rest, so my hand moves forward (relative to COM) much more than the rest moves rearward (relative). I beat you by 0.995 foot or something like that. If "relative to COM" is confusing, think about it as speed relative to ground. My hand accelerates more than the rest decelerates, resulting in my hand crossing the finish line ahead of your hand.

Now suppose we are riding side by side, equally matched, both carrying softballs, and the winner is the one whose softball crosses the line first. Again, you confidently ride to the finish, holding your softball. I throw my softball forward, when we are twenty feet from the line. I have beaten you by a bit less than 20 feet. Reason is the same as with the hands.

Finally we are riding side by side, evenly matched, and the winner is the one whose bike - specifically, the leading edge of the front tire - crosses the line first. Again, you confidently ride to the finish, not doing anything but pedaling. I wait until we are a couple feet from the line and extend my hands forward, doing what we call a "bike throw". Just like I beat you by extending my hand in the first race, and beat you by throwing the ball in the second race, I beat you now, by "throwing" the bike. Since I have to maintain my hold on the bike (unlike the softball), I can only beat you by the distance that I can extend my arms and torso (maybe a foot), slightly reduced by the rest of me moving rearward (relative to COM). But I only need an inch.

That is the reality. Your analysis is wrong. If the winner in these races was the rider whose got the combined center of mass of himself and his bike across the line first, then you'd be on the right track. That is not, however, the rule of a bike race.

Last edited by jyl; 08-24-15 at 09:38 AM.
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