WHOOPS! ANOTHER Dead Mountain Biker!

On Thursday, July 4, 2013 7:41:22 AM UTC-7, Blackblade wrote:
Impossible, as anyone with a knowledge of physics knows: unless you are travelling in a perfect straight line, you are ALWAYS accelerating, hence always causing erosion, and therefore always doing more harm than a hiker.



You were doing so well until the end ... I almost thought you'd understood.



Yes, if the vector changes then you 'accelerate' in the physics sense. However, firstly, you are frequently travelling in a nearly straight line

Hogwash. I have yet to see a trail that was a perfectly straight line (no sideways movement & no vertical movement). Nature isn't like that. So the bike is continually accelerating, hence applying shear (horizontal) force to the trail. That's what causes erosion. The hiker applies much less force, hence less erosion.

The reason that bikes are more energy-efficient is that the human body generates heat. So most of the hiker's energy is not applied to the trail, but lost to heat.

and, secondly, you're impacting far LESS than a hiker. Let me demonstrate for the hard of understanding ...



You walk over a 10m section of track vs you cycle over a 10m section of track



You are travelling at 15mph on the bike and 3mph walking



You generate 200 watts of power ... so you will accelerate if friction is lower than 200 watts and decelerate if lower.



Riding Walking

Power 200 200

Speed 15 3

Time on Trail 1.5s 7.5s

Energy Imparted to system 300Joules 1,500Joules



Additionally, since the biker is moving faster, they will encounter 25 times the air resistance.



So, the hiker will put a LOT more energy into the trail in friction than the rider. And that is exactly WHY bikes go faster for the same energy input ... they don't lose so much energy to friction.

Not in the bike, but they DO create a lot more friction on the trail (i.e., accelerate/decelerate).

You could never even pass a physics course, with this kind of specious reasoning. Vandeman STILL 1000, mountain bikers ZERO.

Name-calling is a sure sign of desperation. You can't possibly win, because you are just WRONG! It must be pretty embarrassing for a psychologist to understand physics better than you! Of course, it's easy, because you refuse to tell the truth.



Ah, you think name calling is wrong now do you Mr Vandeman ? I take it that you will therefore be immediately ceasing your ad-hominem attacks and focussing just on the facts.



As to understanding physics better, if you were right then bikes would travel slower than walkers ... I suggest you go do some study.

Yawn

On Thursday, July 4, 2013 1:14:53 PM UTC-7, I love Mike wrote:
Yawn

Sleeping in class again? No wonder you are so ignorant....

Yawn. Boring.

Hogwash. I have yet to see a trail that was a perfectly straight line (no sideways movement & no vertical movement). Nature isn't like that. So the bike is continually accelerating, hence applying shear (horizontal) force to the trail. That's what causes erosion. The hiker applies much less force, hence less erosion.

I didn't say perfectly straight ... I said roughly so. And the energy imparted to the trail MUST be much less OR the bike would go slower.

The reason that bikes are more energy-efficient is that the human body generates heat. So most of the hiker's energy is not applied to the trail, but lost to heat.

Total and utter balderdash. If the biker and the hiker are both producing 200watts then they will also produce exactly the SAME amount of heat. By going faster the biker will lose more to air friction because that goes up as the square of speed.

You're looking for magic here Vandeman ... chemical energy gets converted to motion and heat ... it's not magically different whether that energy goes into moving the legs to walk or moving the legs to rotate pedals.

You could never even pass a physics course, with this kind of specious reasoning. Vandeman STILL 1000, mountain bikers ZERO.

Then find the flaws Vandeman ... and then let me know when you can't. I, unlike you, bothered to look it up to check I was right !

On Friday, July 5, 2013 1:53:30 AM UTC-7, Blackblade wrote:
Hogwash. I have yet to see a trail that was a perfectly straight line (no sideways movement & no vertical movement). Nature isn't like that. So the bike is continually accelerating, hence applying shear (horizontal) force to the trail. That's what causes erosion. The hiker applies much less force, hence less erosion. I didn't say perfectly straight ... I said roughly so.

That is scientifically meaningless. No trail is ever straight, and no rider is ever travelling at a constant speed, so the bike is continually accelerating (in physics terminology), hence causing erosion. Because its speed and weight are greater than the hiker's, its momentum, & hence force, is greater than the hiker. That's why a hiker's tracks are almost invisible, whereas bikers through dirt to the outside on turns, create deep ruts, and leave obvious tire tracks. It's obvious to everyone -- except lying mountain bikers. You already know I'm right. You just don't have the guts to admit it. Thanks for proving that over and over, endlessly.

And the energy imparted to the trail MUST be much less OR the bike would go slower. The reason that bikes are more energy-efficient is that the human body generates heat. So most of the hiker's energy is not applied to the trail, but lost to heat. Total and utter balderdash. If the biker and the hiker are both producing 200watts then they will also produce exactly the SAME amount of heat. By going faster the biker will lose more to air friction because that goes up as the square of speed. You're looking for magic here Vandeman ... chemical energy gets converted to motion and heat ... it's not magically different whether that energy goes into moving the legs to walk or moving the legs to rotate pedals. You could never even pass a physics course, with this kind of specious reasoning. Vandeman STILL 1000, mountain bikers ZERO. Then find the flaws Vandeman ... and then let me know when you can't. I, unlike you, bothered to look it up to check I was right !

Yawn.

That is scientifically meaningless. No trail is ever straight, and no rider is ever travelling at a constant speed, so the bike is continually accelerating (in physics terminology), hence causing erosion. Because its speed and weight are greater than the hiker's, its momentum, & hence force, is greater than the hiker. That's why a hiker's tracks are almost invisible, whereas bikers through dirt to the outside on turns, create deep ruts, and leave obvious tire tracks. It's obvious to everyone -- except lying mountain bikers. You already know I'm right. You just don't have the guts to admit it.. Thanks for proving that over and over, endlessly.

You keep saying "it's obvious" and then spouting drivel.

So, I notice you haven't followed up your ludicrous statement about hikers producing more heat ? Care to justify that one ? Thought not.

You're back to just flailing ... there's so many errors here that I almost don't know where to start.

1. Force multiplied by time equals CHANGE in momentum. Just because something has momentum does not mean it applies more force ... in fact, the faster you go the LESS force you will apply to a given section because you are impacting it for less time.

2. Hikers tracks are not 'invisible'. We did a quick test on some soft ground this weekend; walked a section and then rode it. As predicted, the footprints are deeper than the tyre prints because the weight is applied for longer to a given point.

You're a disgrace to the science ... you're so caught up in what you want the results to be that you can't think straight.

On Monday, July 8, 2013 3:02:33 AM UTC-7, Blackblade wrote:
That is scientifically meaningless. No trail is ever straight, and no rider is ever travelling at a constant speed, so the bike is continually accelerating (in physics terminology), hence causing erosion. Because its speed and weight are greater than the hiker's, its momentum, & hence force, is greater than the hiker. That's why a hiker's tracks are almost invisible, whereas bikers through dirt to the outside on turns, create deep ruts, and leave obvious tire tracks. It's obvious to everyone -- except lying mountain bikers. You already know I'm right. You just don't have the guts to admit it. Thanks for proving that over and over, endlessly. You keep saying "it's obvious" and then spouting drivel. So, I notice you haven't followed up your ludicrous statement about hikers producing more heat ? Care to justify that one ? Thought not. You're back to just flailing ... there's so many errors here that I almost don't know where to start. 1. Force multiplied by time equals CHANGE in momentum. Just because something has momentum does not mean it applies more force ... in fact, the faster you go the LESS force you will apply to a given section because you are impacting it for less time.

That's obvious hogwash. So a biker running into you at 25 MPH will cause less damage than a hiker running into you at 2 MPH?! Idiot.

2. Hikers tracks are not 'invisible'. We did a quick test on some soft ground this weekend; walked a section and then rode it. As predicted, the footprints are deeper than the tyre prints because the weight is applied for longer to a given point. You're a disgrace to the science ... you're so caught up in what you want the results to be that you can't think straight.

As usual, you conveniently forgot to mention that the biker travels several times as far as the hiker, so you have to multiply their impacts several times. Hence, the biker does more total damage. DUH!

That's obvious hogwash. So a biker running into you at 25 MPH will cause less damage than a hiker running into you at 2 MPH?! Idiot.

Oh for goodness sake. You're not 'running into' the ground are you ? You are completely forgetting that momentum has a vector (look it up).

Would you rather I rode over your foot or stopped on top of it ? That's the analagous event .. not a collision.

2. Hikers tracks are not 'invisible'. We did a quick test on some soft ground this weekend; walked a section and then rode it. As predicted, the footprints are deeper than the tyre prints because the weight is applied for longer to a given point. You're a disgrace to the science ... you're so caught up in what you want the results to be that you can't think straight.

As usual, you conveniently forgot to mention that the biker travels several times as far as the hiker, so you have to multiply their impacts several times. Hence, the biker does more total damage. DUH!

The impact will be, overall, DIRECTLY related to the amount of work done .... the energy imparted by the hiker or rider ... which is determined by power output and time. So, if the rider goes further in the same time period they will impact each quantum of trail less ... but there will be more quanta.

Unless you can violate conservation of energy, one of the most fundamental of universal laws, there is only the output of one person whether riding or hiking.