This guy seems to have taken lessons from Peter. I seem to remember a certain letter sent to the Mt. Democrat....

Jon
--------------------------------------------------------------------
July 31, 2002

Doing the math on mountain trail impact

George Morin



Of the letters recently published regarding the hiker/biker trail-impact issue, one was particularly marvelous - citing studies from the University of Guelph and Oakland together concluding "with average amounts of activity, cycling and hiking have similar effects on terrain."

Bear with me while I run these numbers: Say I weigh 160, carry a 20-pound pack, and my average stride is 28 inches. Each hiking boot spreads my 180-pound load over about 30 square inches as it contacts the trail. The surface pressure on the trail is about 6 pounds for each square inch of boot sole. This is my hiker's impact for each 28 lineal inches of trail.

If I'm a mountain biker with a 25-pound bike and the same pack, my load on the trail is 205 pounds. Instead of setting down my boot every 28 inches, now my two tires contact the trail surface CONTINUOUSLY. Say I have a 2-inch tire tread width and 1 inch of each tire's outer circumference contacts the trail surface at any one time. Then, for that 1 lineal inch, I'm loading the trail with my 205 pounds at a surface pressure of about 50 pounds/square inch for each tire. But when I travel the next lineal inch along the trail, I'm loading it again with the same amount; and so on for the entire 28 inches. This is my biker's impact for each 28 lineal inches of trail.

The purist can find flaws in this comparison because it is oversimplified. Things like dynamic force vectors and tread details are omitted. But then, you can run your own numbers if you don't like mine.

The point is it doesn't take a rocket scientist to understand that relative trail impacts between hiker and biker are dramatically different. Anyhow, I'll bet that any candid mountain biker will tell you that these assumptions have been kind because if the tires aren't skidding a lot of the time, it's not as much fun.

George Morin

Nevada City

http://www.theunion.com/apps/pbcs.dll/article?Site=TU&Date=20020731&Category=OPINION&ArtNo=107310024&Ref=AR

this letter? ;)


Dear Editor,

Upon reading Kevin McNaughton’s greatly exaggerated one sided letter, I would appreciate the chance to say a few words.

Mr. McNaughton, I would strongly urge you to get your facts straight before you go out spewing your typical “anti-OHV” nonsense . The overwhelming majority of OHV enthusiasts are quite considerate of the environment, in fact they leave it better than they found it!. To use the less than one percent that are not responsible and dub them “land destroyers” (as you so colorfully put it to evoke sympathy from your readers for your less than factual, bogus rhetoric), is about as logical as me using the extremist tactics of such renegade groups as Earth First (EF), Earth Liberation Front (ELF), and Animal Liberation Front (ALF) as the general consensus and public image for environmentalists such as yourself. For anyone who doesn’t know, these groups use “no holds barred” tactics - such as equipment sabotaging, tree spiking, arson, crop damage, road blocking and even attempting bodily harm to workers, Forest Service Personnel, and Law Enforcement officers – under the guise of saving the planet. These people are not the representation of a true environmentalist, just as the “land destroyers” (your term) you singled out are not a representation of the OHV community.

In fact, we (the OHV community) spend countless hours planning and executing organized cleanup runs, trail maintenance projects, outdoor recreation trips for the disabled and less fortunate, and charity runs for such organizations as the MDA. I would urge you to contact the County of Placer, as well as the Lahonton Water District, the BLM, the USFS, the MDA, and countless local land use agencies and charities across the state (and the nation for that matter, although it appears you don’t get out much by your closed minded statements and one sided slurs) and ask them about the countless VOLUNTEERS that have put in COUNTLESS HOURS helping out when the need arises. I personally have driven in excess of 10 hours to sleep for a few hours in the front seat of an Acura, and then tirelessly dig, form, and rock line erosion control ditches for ten hours, then catch a shower and a few hours sleep before driving home again. Why would someone who is “self-centered, abusive, and stupid” do this? Since you obviously do not have the answer, I’ll help you out.

We do these things because we care! We are ENVIRONMENTALISTS! As hard as you may find this to believe, this is OUR planet too. We know that and we respect that. We are a lot farther from “self-centered” than you have presented yourself. We modify our vehicles to handle rough terrain without breaking, but more importantly to maintain tire contact with the ground – thus maintaining traction and minimizing impact. We consistently carryout MORE waste than we carry in. I typically find more trash and garbage from inexperienced hikers, than from OHVers. All of the trails we use are approved routes by the USFS, the BLM, and/or any local agencies. For some reason, because we choose to recreate using our vehicles, and you do not, you think you are better than us. You think you know what is best and you know what types of activities describe our group. I hope everyone that reads this can see that you are extremely biased and have no idea what you are talking about. I hope they will also take the time to find out the facts from multiple perspectives on an issue before forming biased one sided opinion, such as the one you have clearly demonstrated.

Since you like Physics so much, try this on for size. A properly driven four wheel drive vehicle has LESS impact on the ground/per person than a hiker. Here’s why:

For this example, we’ll use a person’s weight to be 150 pounds (since we all have beer guts like you pointed out), and a size 10 shoe with a good pair of hiking boots. For the vehicles we’ll call vehicle weight 5000 pounds (which is outrageously high, but is also to your benefit), the average tire size of 35x12.50x15 with 12psi of air in each of the four tires. (All of these can vary greatly, but I think these are more than fair averages.)

Every time the hiker lifts a foot to take a step, the remaining foot on the ground has a contact patch of approximately 14 square inches – this equates to ~ 10.75 pounds per square inch per hiker.

In the next example we have a 5000 pound “earth destroying jeep” (your carefully chosen words again), with four tires @ 12psi. The average contact patch of a properly aired down 35x12.50 tire @12psi is ~ 16x13 inches, or 208 square inches. Now there are four tires, so that’s a total of 832 square inches of contact area with the ground. Let’s divide this into the vehicle weight of 5000 pounds. We get 6 pounds per square inch for a single driver. Now everyone knows the first rule of OHVing is “NEVER go alone”. So lets throw in a couple of buddies and their gear @ 200/person. So now we have 5400/832 gets us 6.5 pounds per square inch. That’s a little less than half than that of a hiker….but wait that’s for 3 people! This gives us approximately 2.2 pounds per square inch per person – almost 1/5 the impact of a hiker!

So there you have your physics, 3 people hiking into the forest have the potential to create almost 5 TIMES the erosion on the trail as a properly equipped and responsibly driven “land destroying jeep” carrying those same 3 people.

Just for the record, I am not a Democrat, nor am I a Republican - but I AM 100% AMERICAN and slightly irritated by your frivolous attempt to distort the facts and take away my family’s freedom to visit OUR Public Lands in the continually responsible manner we have always exercised.

Sincerely,
Peter S. Di Primo

(If you choose to publish my editorial, please do not publish address, e-mail address, or phone number – city and state are ok to publish)

Yellowsub1962@sbcglobal.net

Can I use this too Pete?

Originally posted by primergray
Can I use this too Pete?

NOOOOOOOOOOOOOOOOOOOOO!!!


you can use parts of it but it was in response to a different letter... just don't want you to send it in thinking it's for this one...


:usa:

I just sent this one in in response to this thread:




I did the math on mountain trail impact.

Peter S. Di Primo

Mr. George Morin, I feel you have a few errors in your equation. You stated your "contact patch" of each of your boots is about 30 square inches. I find it hard to believe you make any forward progress walking flat footed with both of your feet contacting the ground simultaneously. Taking this into account I would say your contact patch is more realistically 8-12 sq inches. To move forward, you must push off with one foot, putting all your weight on it, even if only momentarily. I'm sure you are like most people in the fact that you do NOT walk flat footed, therefore mainly using the "ball" of your foot for "pushing forward". Lets say your contact patch is 4" wide by 3" long (more than likely an exaggeration, but in your favor). Your 180lbs of you and your gear is now spread over 12sq inches giving you an impact of 15 pounds per square inch. This is almost 3 times greater than the bicycle in your example.

In all fairness, there is the potential for a Mountain Biker to abuse the trail, (though "skidding" (which you mislabeled as a way to have more fun) is not a general practice in Mountain biking any more than it is in driving your car as a skidding vehicle is an out of control vehicle - which could lead to crashing and injury, two things Mountain Bikers try to prevent) just as there is potential for ANY type of Trail User to abuse the trail.

In conclusion, I am not trying to create a negative hiking image (as you appear to be attempting to do to Mountain Bikes), I am only attempting to provide everyone with a fair comparison, using proper science - something which is conveniently becoming less and less prominent these days when dealing with issues concerning the environment.



:usa: