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Please stay on the trail.

FAQ and threads for those just starting to hike the Colorado 14ers.
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Re: Please stay on the trail.

Postby DeucesWild » Mon Oct 01, 2012 10:47 pm

Although I haven't read every post, I don't recall any mention made of: weight = mass x acceleration

The bike isn't sitting still.
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Re: Please stay on the trail.

Postby HikerGuy » Mon Oct 01, 2012 10:57 pm

I think the more serious concern is not some braided trail on a mountain, but the lack of science education in this country.

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Re: Please stay on the trail.

Postby wildlobo71 » Mon Oct 01, 2012 11:22 pm

HikerGuy wrote:I think the more serious concern is not some braided trail on a mountain, but the lack of science education in this country.


:lol: May the FORCE be with you, Deuce.
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Re: Please stay on the trail.

Postby crossfitter » Mon Oct 01, 2012 11:38 pm

ajkagy wrote:Think of it this way...if I have a high pressure air tank with 5000 PSI of air in the tank laying on the ground, it's not putting 5000 PSI against the ground, lol


And you've found the real key here. Pressures do not necessarily need to be balanced but forces do. I'll leave the math up as an exercise to the reader, but the total force exerted on the ground is a combination of the internal pressure*contact area and the load carried by the structure. In the air tank example, the steel structure carries nearly the entire load whereas in a balloon almost none of the load is carried by the walls. In a bike tire that distribution will fall somewhere in between but I would hazard a guess that not much load is carried by the tire walls.

However, analyzing static forces isn't particularly useful or accurate. Shear forces which easily redistribute soil and rock contribute far more to erosion than simple compression, and that analysis gets harder to do on the back of an envelope. A bike may not be any worse than a person if it is rolling, but what about when the rider slams on the brakes? The easiest way to settle this is to look at erosion on bike paths vs. hiking trails while normalizing for usage.

Then again, Elbert is already a cattle trail so....eh, whatever.
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Re: Please stay on the trail.

Postby Dex » Tue Oct 02, 2012 5:41 am

mtnfiend wrote:I can't believe I'm doing this....

Dex wrote:The issue isn't about the PSI in the tire. It is about the PSI on the ground - bike tire vs a hiker's foot.


Yes, that was one of my immediate thoughts as well. I know the math I posted above is simplified, but please, please, post a mathematical solution that contradicts my above. Please!!



Of course I could write a formula, and it would properly take into account, mass, speed, footprint, and tire construction (an important factor not mentioned so far). Then I would compare that with a hiker with the same variables - except switch out tires for boots.

But, if I did that; what would you do today?
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Re: Please stay on the trail.

Postby Bean » Tue Oct 02, 2012 7:22 am

Dex wrote:
mtnfiend wrote:I can't believe I'm doing this....

Dex wrote:The issue isn't about the PSI in the tire. It is about the PSI on the ground - bike tire vs a hiker's foot.


Yes, that was one of my immediate thoughts as well. I know the math I posted above is simplified, but please, please, post a mathematical solution that contradicts my above. Please!!



Of course I could write a formula, and it would properly take into account, mass, speed, footprint, and tire construction (an important factor not mentioned so far). Then I would compare that with a hiker with the same variables - except switch out tires for boots.

But, if I did that; what would you do today?

I'm pretty sure people have done thesis-level papers on this subject. We are but amateurs (at best) touching only the surface of the issue.
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Re: Please stay on the trail.

Postby ajkagy » Tue Oct 02, 2012 7:34 am

mtnfiend wrote:I like your thought process ajkagy, and it is that simple. Although the high pressure gas cylinder is not a straight apples to apples comparison. A high pressure gas cylinder is a rigid structure, quite unlike a tire, and that is exactly why I set out to measure the contact area of my bike while it had a known force on it. To determine the pressure I exert on the ground, I have to know my force (not weight - although they are sometimes the same quantity) and the contact area.


yea the gas cylinder was a bad comparison since the strength of the steel/carbon is pushing bad equally on the gas in the cylinder. Same with the tire walls in the bike tire and i imagine the PSI inside the tire is a bit more once it's bearing weight and compressing the overall volume inside the tire :)

regardless, people need to quit picking on bikers :-D
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Re: Please stay on the trail.

Postby tlongpine » Tue Oct 02, 2012 8:18 am

TallGrass wrote:
tlongpine wrote:The discussion isn't a question about what is causing the erosion, the question is how to mitigate it.

So we have to mitigate erosion without understanding the cause(s)? How does that process go?


No, sophist. The causes are understand: poor trail engineering that is ill suited for any user type.

The science is in. You can't presume the rest of this forum is as clueless as you are (or stuck at the same step of the process of inquiry) because you haven't read it. Please, before posting more condescending rhetorical questions, read it: http://www.imba.com/resources/research/trail-science
I am unable to walk away from the mountain without climbing it. An unclimbed mountain tugs at my consciousness with the eternal weight of time itself. Until I've pressed my face into it's alpine winds, hugged it's ancient granite walls, and put it's weathered summit beneath my heal I'm unable to resist it's attraction.Knowing nature gives the mountain more time than she gives us adds urgency to the obsession. As has been said before; the mountain doesn't care.

It can wait forever. I cannot.

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Re: Please stay on the trail.

Postby tlongpine » Tue Oct 02, 2012 8:27 am

DeucesWild wrote:Although I haven't read every post, I don't recall any mention made of: weight = mass x acceleration

The bike isn't sitting still.


THIS IS SO WRONG IT HURTS.

Mass x Acceleration = FORCE.

(of course, I might have missed any/all sarcasm)
I am unable to walk away from the mountain without climbing it. An unclimbed mountain tugs at my consciousness with the eternal weight of time itself. Until I've pressed my face into it's alpine winds, hugged it's ancient granite walls, and put it's weathered summit beneath my heal I'm unable to resist it's attraction.Knowing nature gives the mountain more time than she gives us adds urgency to the obsession. As has been said before; the mountain doesn't care.

It can wait forever. I cannot.

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Re: Please stay on the trail.

Postby DeucesWild » Tue Oct 02, 2012 8:33 am

tlongpine wrote:
DeucesWild wrote:Although I haven't read every post, I don't recall any mention made of: weight = mass x acceleration

The bike isn't sitting still.


THIS IS SO WRONG IT HURTS.

Mass x Acceleration = FORCE.


wildlobo71 wrote:
HikerGuy wrote:I think the more serious concern is not some braided trail on a mountain, but the lack of science education in this country.


:lol: May the FORCE be with you, Deuce.


I always try to defer to the experts among us. In this case, I'm not a physician so I'll have to apply Mensa intuitive reasoning and get back to you both, Wildbobo and LooongPine.
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Re: Please stay on the trail.

Postby Jim Davies » Tue Oct 02, 2012 9:26 am

cheeseburglar wrote:After 9 of us stormed Fortress Peak on Saturday, which is some obscure 13er hill somewhere in the wilderness, there should be a trail.
Please follow it.

I've heard it takes 10 hikers to create a social trail. Not sure how many bikers.
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Re: Please stay on the trail.

Postby crossfitter » Tue Oct 02, 2012 9:44 am

tlongpine wrote:
DeucesWild wrote:Although I haven't read every post, I don't recall any mention made of: weight = mass x acceleration

The bike isn't sitting still.


THIS IS SO WRONG IT HURTS.

Mass x Acceleration = FORCE.

(of course, I might have missed any/all sarcasm)


It's actually not wrong at all. Weight is simply force due to gravity, and the equation deuces posted is perfectly accurate (if somewhat simplified).
- A mountain is not a checkbox to be ticked
- Alpinism and mountaineering are not restricted to 14,000 foot mountains
- Judgment and experience are the two most important pieces of gear you own
- Being honest to yourself and others about your abilities is a characteristic of experienced climbers
- Courage cannot be bought at REI or carried with you in your rucksack


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