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Please stay on the trail.

FAQ and threads for those just starting to hike the Colorado 14ers.

Re: Please stay on the trail.

Postby Bean » Mon Oct 01, 2012 4:02 pm

uwe wrote:Hi,

Let's get back to the original theme.
STAY ON THE FRIGGIN' TRAIL! Pretty simple.
Need to muddy the boots anyway to show that you're doing something.
I am always amazed by folks who are afraid to get a little dirt and mud on the boot.

60 posts of "yeah! stay on the trail!" would be neither interesting nor useful. Over time, forum threads frequently diverge from the original subject (it can be slight - like with this thread - or it can go completely off the rails).

Welcome to the internets.
gdthomas wrote:Bean, you're an idiot.

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Re: Please stay on the trail.

Postby uwe » Mon Oct 01, 2012 4:20 pm

Hi Bean,

Nice to meet you.
I am flattered to be quoted.
Thank you, thank you, thank you.

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Re: Please stay on the trail.

Postby Dex » Mon Oct 01, 2012 4:30 pm

Bean wrote:
mtnfiend wrote:Bottom line - just because you have 30 psi in the tires does not mean you exert 30 psi to the ground.

Unless you're talking shear forces (I don't think you are), that's incorrect - unless you're concerned about small parts of the tread pattern exerting higher pressures than other parts of the tire - but it all averages out over the surface. But like tlongpine said, that's not particularly relevant if we're talking about practical trail management. Also, I was kidding about the pascals thing.



So, to lessen the PSI on the ground all a mountain biker needs to do is decrease the psi of the tire inflation to 25psi or even 20 psi? And to top that, it doesn't make a difference if the rider is 100lbs or 300lbs or the weight of the bike!

Man, I should have paid better attention to that new math.
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Re: Please stay on the trail.

Postby madbuck » Mon Oct 01, 2012 4:36 pm

Dex wrote:
So, to lessen the PSI on the ground all a mountain biker needs to do is decrease the psi of the tire inflation to 25psi or even 20 psi?


Actually, yes.
Bigger contact patch from a "flatter" tire gives you the same force spread out over a larger area. Think about riding on sand or snow.

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Re: Please stay on the trail.

Postby Average Joe » Mon Oct 01, 2012 4:41 pm

madbuck wrote:
Dex wrote:
So, to lessen the PSI on the ground all a mountain biker needs to do is decrease the psi of the tire inflation to 25psi or even 20 psi?


Actually, yes.
Bigger contact patch from a "flatter" tire gives you the same force spread out over a larger area. Think about riding on sand or snow.


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I have no idea who's right but couldn't resist.

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Re: Please stay on the trail.

Postby TallGrass » Mon Oct 01, 2012 4:43 pm

tlongpine wrote:Bean is talking about the PSI within the tire while you are talking about PSI upon the ground.

So the "50-100+ psi" ...
Bean wrote:A hiking boot (as tends to be worn by anti-bike troglodytes) with a raised heel will be less, but close enough (I'll make up the difference in average hiker weight incl. gear). At 200lb all geared up, that's 2psi standing perfectly still, 4psi on one foot, and 50-100+ psi when stepping forward. Meanwhile, 30psi in a bike tire is 30psi. A fatbike can go as low as single-digit air pressure.

is not referring to pressure upon the ground, but... within the boot? :-s
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?

Better still, who'd want to volunteer their time to work this as a CFI project? Wouldn't organizing something like that have the best impact?
Not sure if I'll do more 14ers. The trip reports are too tiring. :wink:

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Re: Please stay on the trail.

Postby Dex » Mon Oct 01, 2012 4:52 pm

madbuck wrote:
Dex wrote:
So, to lessen the PSI on the ground all a mountain biker needs to do is decrease the psi of the tire inflation to 25psi or even 20 psi?


Actually, yes.
Bigger contact patch from a "flatter" tire gives you the same force spread out over a larger area. Think about riding on sand or snow.


So what you are telling us is that if the max pressure on the tire is 50 psi, then the max pressure it can a bike with 400lb rider can put on the ground is 50 psi?
Seriously?
Montani Semper Liberi
"Please use the comments to demonstrate your own ignorance, unfamiliarity with empirical data and lack of respect for scientific knowledge. Be sure to create straw men and argue against things I have neither said nor implied. If you could repeat previously discredited memes or steer the conversation into irrelevant, off topic discussions, it would be appreciated. Lastly, kindly forgo all civility in your discourse . . . you are, after all, anonymous." Barry Ritholtz

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Re: Please stay on the trail.

Postby planet54 » Mon Oct 01, 2012 4:53 pm

Science: Science does not produce wisdom. While the insights of science can help us to change our world,only human thought and concern can enlighten us about the path we should follow in life.

In other words,science can help fix this problem, but it will take people that give a damn to get it done.
"The world is a great book,of which they that never stir from home read only a page." St. Augustine
"Climbing K2 or floating the Grand Canyon in an innertube;there are some things one would rather have done than do." Edward Abbey

Re: Please stay on the trail.

Postby Bean » Mon Oct 01, 2012 5:16 pm

Dex wrote:So what you are telling us is that if the max pressure on the tire is 50 psi, then the max pressure it can a bike with 400lb rider can put on the ground is 50 psi?
Seriously?

Yes. The contact patch will increase in size. There may be slight pressure changes as the tire deforms but that will be insignificant. Assuming a square contact patch, all you'd need is 2" x 2" (per tire) at 50psi to support 400lb.
gdthomas wrote:Bean, you're an idiot.

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Re: Please stay on the trail.

Postby Bean 2 » Mon Oct 01, 2012 6:18 pm

Bean wrote:
Dex wrote:So what you are telling us is that if the max pressure on the tire is 50 psi, then the max pressure it can a bike with 400lb rider can put on the ground is 50 psi?
Seriously?

Yes. The contact patch will increase in size. There may be slight pressure changes as the tire deforms but that will be insignificant. Assuming a square contact patch, all you'd need is 2" x 2" (per tire) at 50psi to support 400lb.


Dex, at the end of the day all of this physics talk is insignificant. The point is that walking downhill is for hiking boot wearing troglodytes (yes, that's right, troglodytes) and mountain biking/skiing is the way to go. If you are looking to build muscle (you can always use my calves for a good example of built muscle (my calves (which are gigantic FYI) can be seen in multiple threads and trip reports on this site)) you can always take up mountain biking and skiing, as they are most definitely NON-troglodyte methods of travel. With the aid of my physics textbook I can talk PSI and other such concepts all night but let's get to the bottom line here; and that is building muscle in it's finest form (my calves for example (which happen to be huge)) is not related to physics or trail design. Ergo this PSI conversation is more or less irrelevant...
gdthomas wrote:

Bean, you're an idiot 2.

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Re: Please stay on the trail.

Postby Bean » Mon Oct 01, 2012 6:20 pm

Bean 2 wrote:Dex, at the end of the day all of this physics talk is insignificant. The point is that walking downhill is for hiking boot wearing troglodytes (yes, that's right, troglodytes) and mountain biking/skiing is the way to go. If you are looking to build muscle (you can always use my calves for a good example of built muscle (my calves (which are gigantic FYI) can be seen in multiple threads and trip reports on this site)) you can always take up mountain biking and skiing, as they are most definitely NON-troglodyte methods of travel. With the aid of my physics textbook I can talk PSI and other such concepts all night but let's get to the bottom line here; and that is building muscle in it's finest form (my calves for example (which happen to be huge)) is not related to physics or trail design. Ergo this PSI conversation is more or less irrelevant...

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Re: Please stay on the trail.

Postby Dex » Mon Oct 01, 2012 6:28 pm

Bean wrote:
Dex wrote:So what you are telling us is that if the max pressure on the tire is 50 psi, then the max pressure it can a bike with 400lb rider can put on the ground is 50 psi?
Seriously?

Yes. The contact patch will increase in size. There may be slight pressure changes as the tire deforms but that will be insignificant. Assuming a square contact patch, all you'd need is 2" x 2" (per tire) at 50psi to support 400lb.


No it won't, it is a tire - too much pressure and it will blow.

You are equating internal psi with external psi on the ground.

Where is Bean2 when you need him.
Montani Semper Liberi
"Please use the comments to demonstrate your own ignorance, unfamiliarity with empirical data and lack of respect for scientific knowledge. Be sure to create straw men and argue against things I have neither said nor implied. If you could repeat previously discredited memes or steer the conversation into irrelevant, off topic discussions, it would be appreciated. Lastly, kindly forgo all civility in your discourse . . . you are, after all, anonymous." Barry Ritholtz

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