Bike Myths We Wish Would Die
02-21-23, 09:40 PM
#476
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...should be pretty easily refuted then. Take your shot. I promise I'll read it and apologize if I'm wrong, on how those two simple lines, diverging, are a good (if simplified) illustration of how the differences applied to weight wheel and frame become more obvious as the quantities increase. Cross my heart.
Alternatively, you can toss out another one liner, which seems to be your forte. Those are good too.
Alternatively, you can toss out another one liner, which seems to be your forte. Those are good too.
02-21-23, 09:51 PM
#477
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The use of limits in Calculus allows for elegant solutions which exactly bypass approximation errors. The people you're arguing with are just saying that certain things can usually be ignored in practice because they're of low magnitude and applicability. These are very different things.
02-21-23, 09:56 PM
#478
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...congratulations. You have been telling yourself for so long that differences in static versus rotational acceleration are zero, that you now believe weight (mass) has nothing to do with physics. That, sir, is no small accomplishment. Tell me please, are you perchance another engineer ?
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02-21-23, 10:01 PM
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...congratulations. You have been telling yourself for so long that differences in static versus rotational acceleration are zero, that you now believe weight (mass) has nothing to do with physics. That, sir, is no small accomplishment. Tell me please, are you perchance another engineer ?
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02-21-23, 10:11 PM
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02-21-23, 10:15 PM
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Let me finish that sentence for you ...
It's also interesting to note that all of the so-called experts all readily admit that saving weight at the wheels results in better acceleration, followed up quickly by "but it doesn't matter because ... it's a really, really small effect."
It's also interesting to note that all of the so-called experts all readily admit that saving weight at the wheels results in better acceleration, followed up quickly by "but it doesn't matter because ... it's a really, really small effect."
Last edited by Jeff Neese; 02-21-23 at 10:18 PM.
02-21-23, 10:17 PM
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The use of limits in Calculus allows for elegant solutions which exactly bypass approximation errors. The people you're arguing with are just saying that certain things can usually be ignored in practice because they're of low magnitude and applicability. These are very different things.
Have I simply misunderstood this idea my entire life ? Without this concept, how can calculus hope to bypass approximation errors ? Like everyone else in this thread, I'm here to learn.
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02-21-23, 10:18 PM
#483
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02-21-23, 10:21 PM
#484
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...should be pretty easily refuted then. Take your shot. I promise I'll read it and apologize if I'm wrong, on how those two simple lines, diverging, are a good (if simplified) illustration of how the differences applied to weight wheel and frame become more obvious as the quantities increase. Cross my heart.
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02-21-23, 10:26 PM
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...well, it's been real, and it's been fun. But I have to go now. Please continue working toward solutions to all the terrible bicycle myths that make our lives a living hell. The world will thank you.
...well, it's been real, and it's been fun. But I have to go now. Please continue working toward solutions to all the terrible bicycle myths that make our lives a living hell. The world will thank you.
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02-21-23, 10:39 PM
#486
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Originally Posted by Jeff Neese
A really really small amount of weight will yield a really, really small difference. A really, really large amount of weight will produce a really, really large change.
You've stated that this is all basic physics. Why don't you put some of your physics knowledge on display and calculate some numbers for us? You can start with something simple: pick two wheel sets and calculate how many extra watts are required to bring the heavier set up to speed when accelerating from a full stop.
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02-21-23, 10:44 PM
#487
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Because bad driving is dangerous. Remove cyclists from the road and pedestrians still get killed as well as other drivers. Eliminate bad drivers and everybody is safe.
If there are records kept for cyclist self injuries or self collision stats, they'd be insignificant. But for cars? It's not uncommon on Friday or Saturday nights, someone somewhere gets into a single car collision.
So if someone thinks cycling is dangerous, better to look at driving instead.
If there are records kept for cyclist self injuries or self collision stats, they'd be insignificant. But for cars? It's not uncommon on Friday or Saturday nights, someone somewhere gets into a single car collision.
So if someone thinks cycling is dangerous, better to look at driving instead.
Last edited by Daniel4; 02-21-23 at 10:49 PM.
02-21-23, 11:23 PM
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This seems like a good place to re-post a link
https://www.globalcyclingnetwork.com...n-cycling-myth
(go to 18:00 if you want to skip to the summary)
and insert this quote from another thread:
https://www.globalcyclingnetwork.com...n-cycling-myth
(go to 18:00 if you want to skip to the summary)
and insert this quote from another thread:
Originally Posted by RChung
Back in 2011 I worked a little bit on modeling the team pursuit in prep for the 2012 Olympics. (For oddball reasons we worked with the American and Canadian women's pursuit teams). One of the tricky things is that in team pursuit there are pretty wild swings in power (and thus acceleration) as you rotate both through the team and also around the velodrome. Wheel speed actually rises and falls more than center of mass speed since in the turns the bikes lean over so the wheels take a longer path than the rider, and the center of mass drops and then rises as you come out of the turn and onto the straights.
So we knew the geometry of the track and how much each rider would lean at what speed in each turn--and, we knew the wheel weight, and had figured out "where" in the wheel the "mass centroid" was so we could calculate the moment of inertia. We did this because this was one of the first times we were trying to get good high quality high precision estimates of CdA and Crr from field-based tests using power meters. Our model was very good, so once we had proper estimates of CdA and Crr, and using the carefully calibrated power meters, we could absolutely *nail* the speed for power for a rider both on the straight and on the turns. I was agog that my calculations worked so well--I hadn't actually expected that.
Here's the thing: although we had the moment of inertia for the wheels, it quickly became evident that the MOI was a small enough contribution that we could simplify the model and ignore it. Even though the speeds and accelerations were high, our predictions of speed for power didn't significantly depend on it at all.
So we knew the geometry of the track and how much each rider would lean at what speed in each turn--and, we knew the wheel weight, and had figured out "where" in the wheel the "mass centroid" was so we could calculate the moment of inertia. We did this because this was one of the first times we were trying to get good high quality high precision estimates of CdA and Crr from field-based tests using power meters. Our model was very good, so once we had proper estimates of CdA and Crr, and using the carefully calibrated power meters, we could absolutely *nail* the speed for power for a rider both on the straight and on the turns. I was agog that my calculations worked so well--I hadn't actually expected that.
Here's the thing: although we had the moment of inertia for the wheels, it quickly became evident that the MOI was a small enough contribution that we could simplify the model and ignore it. Even though the speeds and accelerations were high, our predictions of speed for power didn't significantly depend on it at all.
Last edited by tomato coupe; 02-21-23 at 11:33 PM.
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02-22-23, 12:02 AM
#489
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The stuff about rotational inertia is pointing to the low magnitude and applicability of something and saying "yeah, we can ignore this in practice because it's miniscule compared with other factors."
These are wildly dissimilar arguments.
02-22-23, 12:44 AM
#490
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Because bad driving is dangerous. Remove cyclists from the road and pedestrians still get killed as well as other drivers. Eliminate bad drivers and everybody is safe.
If there are records kept for cyclist self injuries or self collision stats, they'd be insignificant. But for cars? It's not uncommon on Friday or Saturday nights, someone somewhere gets into a single car collision.
So if someone thinks cycling is dangerous, better to look at driving instead.
If there are records kept for cyclist self injuries or self collision stats, they'd be insignificant. But for cars? It's not uncommon on Friday or Saturday nights, someone somewhere gets into a single car collision.
So if someone thinks cycling is dangerous, better to look at driving instead.
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Ride, Rest, Repeat. ROUVY: terrymorse
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02-22-23, 01:19 AM
#491
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there is always pilot error/sheer heart attack/aneurysm/et al while riding but how many cyclist deaths/life-changing collisions/avoidances are due to automobiles and their proximal influence?
02-22-23, 04:12 AM
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Yeah, thanks for polluting the thread with trolling nonsense again. Jeff Neese gave you a like though. You should be proud.
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02-22-23, 04:16 AM
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So what you need to do are some calculations with actual numbers. That's what engineers do for a living. I can't imagine what you do for a living, but I'm confident it isn't that.
Last edited by PeteHski; 02-22-23 at 04:25 AM.
02-22-23, 04:24 AM
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So maybe you should review their work and publish an article for peer review explaining why the experts are wrong here. If you are right, then your work should become a new benchmark.
Last edited by PeteHski; 02-22-23 at 04:31 AM.
02-22-23, 05:02 AM
#495
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and thanks for not taking all this personally. I don't know you but I have nothing against you no matter how much we disagree .... thanks for reminding me.
02-22-23, 05:07 AM
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it when engineers pretend to be physicists. It makes me smile.
02-22-23, 05:17 AM
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By the way .... it has been a while since I did any research, and it is spotty because of HIPPA laws and such, but as far as I can tell the majority of the thousand (or slightly fewer) cyclists who die each year fall into at least one of these classes----substance-abuse impaired, no lights at night, dark clothing at night, riding the wrong way. As I recall, alcohol was the most common factor.
Drunk guys in black hoodies doing the ninja salmon and getting run down when they flash off the sidewalk right in front of someone pulling out of a driveway is not a "risk factor' which in any way applies to me.
I have found in fact, that over the past three or so decades, drivers have become much more polite and cooperative. I have still seen so really dangerous driving, but I haven't been hit or forced off the road in many many years.
Of course, I have also gotten less reckless and more cooperative.
Drunk guys in black hoodies doing the ninja salmon and getting run down when they flash off the sidewalk right in front of someone pulling out of a driveway is not a "risk factor' which in any way applies to me.
I have found in fact, that over the past three or so decades, drivers have become much more polite and cooperative. I have still seen so really dangerous driving, but I haven't been hit or forced off the road in many many years.
Of course, I have also gotten less reckless and more cooperative.
02-22-23, 05:52 AM
#498
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By the way .... it has been a while since I did any research, and it is spotty because of HIPPA laws and such, but as far as I can tell the majority of the thousand (or slightly fewer) cyclists who die each year fall into at least one of these classes----substance-abuse impaired, no lights at night, dark clothing at night, riding the wrong way. As I recall, alcohol was the most common factor.
Drunk guys in black hoodies doing the ninja salmon and getting run down when they flash off the sidewalk right in front of someone pulling out of a driveway is not a "risk factor' which in any way applies to me.
I have found in fact, that over the past three or so decades, drivers have become much more polite and cooperative. I have still seen so really dangerous driving, but I haven't been hit or forced off the road in many many years.
Of course, I have also gotten less reckless and more cooperative.
Drunk guys in black hoodies doing the ninja salmon and getting run down when they flash off the sidewalk right in front of someone pulling out of a driveway is not a "risk factor' which in any way applies to me.
I have found in fact, that over the past three or so decades, drivers have become much more polite and cooperative. I have still seen so really dangerous driving, but I haven't been hit or forced off the road in many many years.
Of course, I have also gotten less reckless and more cooperative.
You always blame the victim?
Cycling is very risky.
02-22-23, 05:58 AM
#499
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Does it count if I almost double majored in physics? I dropped it Senior year needed just the last quantum mechanics class but the Prof was always gone traveling to the accelerator or some radar telescope in PR with cute coeds in tow and don't get me started on the constantly drunk physics professor that we had to endure. One day it was announced the drunk old fool won himself the Nobel prize. He hated me freshman year because like the second day we were going over friction crap and he tells us surface area does not matter and he did not appreciate my real world data on 1/4 mile pulls with different tire widths. I can still smell the stench of yesterday's and that day's alcohol on his noble breath.
02-22-23, 06:01 AM
#500
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By the way .... it has been a while since I did any research, and it is spotty because of HIPPA laws and such, but as far as I can tell the majority of the thousand (or slightly fewer) cyclists who die each year fall into at least one of these classes----substance-abuse impaired, no lights at night, dark clothing at night, riding the wrong way. As I recall, alcohol was the most common factor.
Drunk guys in black hoodies doing the ninja salmon and getting run down when they flash off the sidewalk right in front of someone pulling out of a driveway is not a "risk factor' which in any way applies to me.
I have found in fact, that over the past three or so decades, drivers have become much more polite and cooperative. I have still seen so really dangerous driving, but I haven't been hit or forced off the road in many many years.
Of course, I have also gotten less reckless and more cooperative.
Drunk guys in black hoodies doing the ninja salmon and getting run down when they flash off the sidewalk right in front of someone pulling out of a driveway is not a "risk factor' which in any way applies to me.
I have found in fact, that over the past three or so decades, drivers have become much more polite and cooperative. I have still seen so really dangerous driving, but I haven't been hit or forced off the road in many many years.
Of course, I have also gotten less reckless and more cooperative.
1. HIPAA prohibits reporting of statistical or any other non-identifiable information by health care entities.
2. HIPAA has anything to say about disclosure or gathering of any information by anyone else.
2. HIPAA is HIPPA.
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