Trail damage/shock absorbers/suspension

[Captain Dondo]

On Tue, 08 Apr 2003 08:58:18 +0000, Terri Alvillar wrote:

> So it seems the greater shock absorbing system on a mountain bike, the greater damage is possible
> because one can travel at greater speeds and displace more surface material when braking,
> skidding, and accelerating. Terri Alvillar
> http://homepage.mac.com/terrialvillar/mountainbikedamage/PhotoAlbum11.html

I love these physics arguments. They are so unproductive....

OK, soil fails not because of FORCE, but because of PRESSURE. Two completely different concepts.
(Look it up in any soils book; the bearing capacity of soil is in force/area, not force.)

Pressure is always equal to the pressure in one's tires. Exceed that, you get snakebite punctures.

Granted, there are dynamics in play like erosion, liquefaction, and who knows what else, but
the fact remains that there is no neat, clear answer. No need to argue about suspension or
anything else.

As to what is worse, who knows? Ultimately, does it matter?

Trails will be built, maintained, and used. If you're against it, get over it, cooperate and you'll
get a lot more achieved.

BTW, Terri, I looked at your site, and the "illegal" trail. Looks like a well-maintained trail in a
recreational area. It seems to me that if it was illegal, surely your local Soils Conservation
folks - or whoever has jurisdiction over soil disturbing activities - would have taken enforcement
action, no?

Certainly, "thousands of cubic yards" of excavation is a major project that would involve hundreds
of dump truck loads, excavators, and large backhoes. Not something one does "just for fun". It would
also have to be permitted under local laws and under the federal Clean Water Act. I can maybe see
where a bobcat was used to move a bit of dirt. So, is it really illegal, or do you just not like it?
Or are you exaggerating the "thousands of yards" just for fun? Tell the truth, now.

-Dondo

 

[Bomba]

Terri Alvillar wrote:

> So it seems the greater shock absorbing system on a mountain bike, the greater damage is possible
> because one can travel at greater speeds and displace more surface material when braking,
> skidding, and accelerating.

Yup, exactly. You should also look at pneumatic tyres as they allow greater speeds and displace more
surface material. Perhaps you should campaign for solid tyres too.

You should also take in to account that greater speeds and distances are achieved by fitter riders,
yet generally they weigh less. On the other hand, fatter riders exert a higher pressure (F=MA). Now
there's a quandry...

Perhaps if you limited mountain biking to light, fit riders who are only allowed to ride rigid bikes
for a limited number of miles with thin solid tyres, environmental impact would be minimised,
pollution would disappear, the Ozone would start self-repairing and the world would be saved. All
thanks to the genius Terri Allivar. Huzzah!

 

[Jeff Strickland]

"Terri Alvillar" <[email protected]> wrote in message
news:[email protected]...
> "Jeff Strickland" <[email protected]> wrote in message
news:<[email protected]>...
> > "Mike Vandeman" <[email protected]> wrote in message
> > news:[email protected]...
> > > On 3 Apr 2003 21:30:56 -0800, [email protected] (Terri Alvillar) wrote:
> > >
> > > .I wonder if any studies have been done to correlate mountain bike .equipment shock absorbers
> > > and suspension with damage to terrain? Is .the damage to terrain commensurate with the level
> > > of shock absorbing .technology on the vehicle?
> > >
> > > Yes. By Newton's laws of physics, every action has an equal and
opposite
> > > reaction. In other words, the force applied to the ground (or anything
> > else in
> > > their path, such as a plant, animal, or person) is identical to the
force
> > > applied to the bike. The reason that mountain bikes are built much
> > stronger than
> > > normal bikes is that they encounter much greater FORCES. Therefore,
they
> > apply
> > > much greater forces to the ground & everything else in their path. QED
> >
> > Technically, a mountain bike with a shock absorber should have less of
an
> > impact than one without a shock absorber. Think of the words being used here, SHOCK ABSORBER. A
> > shock absorber absorbs shocks, therefore by definition, less of an impact.
> >
> > Think of the water barrels they (CalTrans or others) place on the impact-side of a sign or post.
> > The sign or post might weigh more, but
the
> > impact upon objects that strike the sign or post is lessened. In the
world
> > of bikes and dirt, the dirt is the object that constantly stirkes the
bike
> > (trying to keep the analogy straight), or in other words, the impact of
the
> > bike striking the ground repeatedly is lessened because of the shock absorber. Newton's Law does
> > not take into account the affects of
external
> > forces, such as a shock absorber.
>
>
> So it seems the greater shock absorbing system on a mountain bike, the greater damage is possible
> because one can travel at greater speeds and displace more surface material when braking,
> skidding, and accelerating.

Technically, a bike with greater shock absorbing ability will do less damage. Consider the facts, if
you dare. A bike is a moving object, and the impact each time it touches anything is either directed
at the point of impact if no shock absorbsion system, or is spread across a wide area if there is a
shock absorbsion system. If a tire is impacting the ground, and there is a shock, then the impact is
very slight at the point of impact, and is gradually spread over a wide area. Try as hard as a rider
might, a shock will lessen the burden of impact, that is the whole point of having one.

 

[Peterh]

Terri Alvillar wrote:

>I think Pete H has just violated the monster ego ordinance. Did you mean semantics? Terri Alvillar
>
>
My monster's ego is quite modest. He has bitten only three Seventh Day Adventists and one Democrat
in the last year.

Pete H

--
The best thing to do with a stupid remark is to not hear it.
R. Heinlein

 

[Mike Vandeman]

On Mon, 7 Apr 2003 15:53:20 +1200, "Westie" <[email protected]> wrote:

. ."Michael Paul" <[email protected]> wrote in message
.news:[email protected]... .<snip> .> > > .> > .> > It is storing it for
brief periods of time. When the spring/air is .> > compressed, energy is stored ( U = k x^2 ).
However, damped suspension .> > results in the force being spread over a long period of time - thus,
a .> > smaller impulse, and less force to any one part of the trail.

So the bike gets lighter at certain places? BS.

The .> > overall total is the same, but it spreads out the high pressures a bit. .> > And then
there are the frictional losses, but those aren't usually too .> > much of a big deal on bikes...
unless you're running Judy's .> > .> > Jon Bond .> .> That's the advanced class . .I was
going to say the same thing but you said it better. ;-)

===
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[Mike Vandeman]

On Mon, 7 Apr 2003 21:52:53 +1200, "Westie" <[email protected]> wrote:

. ."Mike Vandeman" <[email protected]> wrote in message
.news:[email protected]... .> On 4 Apr 2003 23:21:23 -0800,
[email protected] (Corvus Corvax) .wrote: .> .> ."Michael Paul" <[email protected]> wrote .> .>
.> .> Physics 101. get the Cliff Notes .> . .> .Uh, try again. Mikey (within his limited
perspective) is correct. Your .> .physics is complete ********. .> .> True. .> .> .The force of the
hiker and the biker on the trail is the same only if .> .both are sitting still. The biker is
moving, and therefore will .> .generally put much greater forces on the trail than a hiker. Hitting
a .> .big bump at 20 mph will put great force on the bike (and therefore the .> .ground), no? .> .
.> .All else being equal, suspension will mitigate this. .> .> Where do you see "mitigate" in
Newton's laws? The suspension may change .the .> force profile across time, but the full force of
the bike + rider's .weight, PLUS .> any downward momentum from the way it is ridden, will eventually
land on .the .> trail. Otherwise, with enough "suspension", an automobile's effect on .someone .>
being driven over could be "mitigated" enough to be harmless, no? .> .> Suspension .> .reduces the
acceleration on the sprung weight, and therefore the .> .force. Of course, all else is probably not
equal, since a suspended .> .rider will probably be going faster. .> .Not that it means anything. "A
completely worthless thing to think .> .about," as Darsh puts it, is probably best. Force on the
ground is a .> .stupid way to measure trail damage. .> .> Wrong. That is the most relevant factor. .
.I wouldn't have thought so. Could you please explain why you consider force .to be the most
relevant factor?

That's what kills animals & plants on the trail, & scares other trail users.

.Could you please explain why ANY hiking damage is OK.

I never said it is, liar.

Why is damage that .accumulates from hiking over 12 months OK if the same damage caused by mtb's
.in 6 months is not?

I never said it is. But bikers cause a lot MORE damage.
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On 7 Apr 2003 06:44:38 -0700, [email protected] (Corvus Corvax) wrote:

.[...crossposting trimmed...] . .I promise I won't drag it out any further than this ;-). . .Mike
Vandeman <[email protected]> wrote .> .> The suspension may change the .> force profile across
time, but the full force of the bike + rider's weight, .> PLUS .> any downward momentum from the way
it is ridden, will eventually land on the .> trail. . .Force isn't like a fluid in a bucket that
eventually has to "land" .somewhere.

It is, if it is caused by gravity. Unless your bike can remain suspended in the air!

There is no law of conservation of force. Also, momentum is .not force. You seem to be a little
confused, which I suppose is not .surprising.

If you have greater momentum, then you will apply greater force to whatever you hit.

.> Otherwise, with enough "suspension", an automobile's effect on someone .> being driven over could
be "mitigated" enough to be harmless, no? . .Bzzt. No Suspension or no suspension, the minimum
equilibrium force on .the trail is going to be the normal force required to support the .weight of
the rider plus bike. Or the car. For the sake of argument, .consider a rider on a perfectly smooth,
flat trail. The force of the .rider on the trail is just equal to the weight of the rider and bike,
.and is independent of how fast the rider is going. This will hold with .or without suspension. Now
put a bump on the trail. When the rider .hits it, the unsuspended experiences additional
accelerations, and .thus puts a greater force on the trail than just the normal force due .to her
weight. Now consider an idealized suspension, for which the .sprung weight experiences no
accelerations, regardless of the terrain. .The forces on the trail will be smaller than in the
unsuspended case. .If we neglect the unsprung mass, the idealized suspension imparts only .normal
forces due to the rider's weight, as if there were no bumps at .all in the trail. No real suspension
is that good, but the force on .the trail will still be less (at the same speed) for a suspended
bike .than an unsuspended one.

Not if the suspension adds weight. Not if it allows the rider to go faster. You forgot about that.
Sorry to burst your bubble.

.Force is not conserved. There is no total amount of force that has to ."land" on the trail. Energy
_is_ conserved. With a suspension, some of .the energy that would have gone into trail erosion or
the rider's .brakes ends up dissipated as heat by the damping in the suspension.

That has NOTHING to do with the force on the ground. The force of gravity is greater (because the
suspension adds weight). The horizontal force is greater, because the suspension lets the rider more
comfortably ride faster. And the greater weight gives the bike more momentum (and hence more force).

.Nonetheless, dry ground can withstand enormous forces without damage. .The more relevant factor is
the rate of erosion, which has more to do .with friction than force. Skidding is bad. Riding is
hunky-dory.

Skidding is caused by horizontal force, so force IS relevant.

.CC

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Mon, 7 Apr 2003 16:33:12 +0100, "Simon" <[email protected]> wrote:

. ."Mike Vandeman" <[email protected]> wrote in message
.news:[email protected]... .<snip> .
. .The rider's weight has no correlation whatever with the bike's realtive .| .sturdiness. .| .| I
never said it does. Mountain bikes were built stronger than normal bikes .| because of the beating
they get, which is IDENTICAL to the beating they .give the .| trail, per Newton. . .Mike can you
give us facts and figures here. You ask us to back our claims .up with such data so I am now
asking you.........prove this. . .My understanding is somewhat like this: .
. Force is equal to mass times acceleration (F=ma). agreed?

Yes, and a suspension bike has more mass.

.On a suspension bike the force is still equal to mass times acceleration. .agreed? . .The force in
discussion is of the wheels on the ground. Agreed?

That's only the horizontal force.

.So force applied to ground from wheels = mass applied to wheel x .acceleration. Agreed? . .However
the mass applied to the wheel is reduced due to the fact the rear .shock is doing its job and
"absorbing" (can you see why we call them shock .absorbers) some of the mass force.

Cute. Explain "mass force". You obviously are WAY over your head.

Hence the oil in the shock or indeed air .will become slighty warmer since the mass force is
converted into heat in .order to absorb some of it. . .The same can be applied to the front forks
and shock absorber set up. . .I am sorry if you cant comprehend this and i have tried to be as
vandeman .friendly as possible.

That isn't the problem. You just don't know anything about physics -- but are unwilling to admit it.

.Simon........doesnt the fact you ride a bike on paved streets negate your .whole ethos and
arguments anyway?

Why? I don't harm any wildlife there.
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Mon, 07 Apr 2003 21:03:56 -0400, PeterH <[email protected]> wrote:

.Mike Vandeman wrote: . .> .>Your inability to understand even "DUH" puts you in a class by
yourself. .>Special, as in "Special Olympics". .> .> .> .> .My understanding of such poor usage is
quite complete. And your ad .hominem tactics seriously erode any chance of credibility. I suggest
you .refine your techniques after consulting the list of logical fallacies .which is neatly
presented here: . .http://www.datanation.com/fallacies/index.htm . .Since you are known to violate a
goodly number of them, you might just .gain a thing or two by becoming familiar with the rules you
flout so .flamboyantly.

As usual, you claim something vague. If you had to be SPECIFIC about what I said wrong, it would be
obvious that you are full of it.

.Pete H

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

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[Mike Vandeman]

On Mon, 7 Apr 2003 21:45:13 +1200, "Westie" <[email protected]> wrote:

. ."Mike Vandeman" <[email protected]> wrote in message
.news:[email protected]... .> On Sat, 5 Apr 2003 12:17:57 +0100, "Simon"
<[email protected]> .> wrote: .> .> . .> ."Mike Vandeman" <[email protected]> wrote in
message .> .news:[email protected]... .> .<snip> .> .| .> .| .And Hikers
HAVE to apply a force to the gorund when they walk, unless .> .they .> .| .can FLY! .> .| .> .| Of
course, only far less than mountain bikers. .> . .> .So its okay to cause trail damage as long as
its less than .mountainbikers. .> .Isnt that what you have just said? .> .> Can't you READ? Where do
you see "okay"? So I guess you agree that hikers' .> damage is less than mountain bikers'.... .> .>
.Simon.........would love to read MV's dissertation.........and yes I .would .> .understand it. .>
.> I guarantee that you won't. . .Why not? You consider using "DUH!" to be an appropriate reply when
someone .asks you a reasonable and civil question. I can't see why he couldn't .understand anything
you've written if that's a good example of what you can .come up with.

Then YOU try it.
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

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[Mike Vandeman]

On Mon, 7 Apr 2003 16:39:20 +0100, "Simon" <[email protected]> wrote:

. ."Mike Vandeman" <[email protected]> wrote in message
.news:[email protected]... .| On Sat, 5 Apr 2003 12:17:57 +0100, "Simon"
<[email protected]> .| wrote: .|<snip> . .| .Simon.........would love to read MV's
dissertation.........and yes I .would .| .understand it. .| .| I guarantee that you won't. . . .Well
let me try. what do you have to hide? What college did you graduate .from? what university? They
would have a copy they could email me.

UCLA. It's at University Microfilms. But you have to be able to read....

.Simon.....with westie on the use of the term "duh" almost ."simpsonesque"..........DoH .

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

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[Mike Vandeman]

On 8 Apr 2003 08:58:18 -0700, [email protected] (Terri Alvillar) wrote:

."Jeff Strickland" <[email protected]> wrote in message news:<[email protected]>... .>
"Mike Vandeman" <[email protected]> wrote in message .>
news:[email protected]... .> > On 3 Apr 2003 21:30:56 -0800,
[email protected] (Terri Alvillar) wrote: .> > .> > .I wonder if any studies have been done to
correlate mountain bike .> > .equipment shock absorbers and suspension with damage to terrain? Is .>
> .the damage to terrain commensurate with the level of shock absorbing .> > .technology on the
vehicle? .> > .> > Yes. By Newton's laws of physics, every action has an equal and opposite .> >
reaction. In other words, the force applied to the ground (or anything .> else in .> > their path,
such as a plant, animal, or person) is identical to the force .> > applied to the bike. The reason
that mountain bikes are built much .> stronger than .> > normal bikes is that they encounter much
greater FORCES. Therefore, they .> apply .> > much greater forces to the ground & everything else in
their path. QED .> .> Technically, a mountain bike with a shock absorber should have less of an .>
impact than one without a shock absorber. Think of the words being used .> here, SHOCK ABSORBER. A
shock absorber absorbs shocks, therefore by .> definition, less of an impact. .> .> Think of the
water barrels they (CalTrans or others) place on the .> impact-side of a sign or post. The sign or
post might weigh more, but the .> impact upon objects that strike the sign or post is lessened. In
the world .> of bikes and dirt, the dirt is the object that constantly stirkes the bike .> (trying
to keep the analogy straight), or in other words, the impact of the .> bike striking the ground
repeatedly is lessened because of the shock .> absorber. Newton's Law does not take into account the
affects of external .> forces, such as a shock absorber. . . .So it seems the greater shock
absorbing system on a mountain bike, the .greater damage is possible because one can travel at
greater speeds .and displace more surface material when braking, skidding, and .accelerating.

You go to the head of the class -- for what it's worth.

.Terri Alvillar .http://homepage.mac.com/terrialvillar/mountainbikedamage/PhotoAlbum11.html

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Mon, 7 Apr 2003 12:46:07 -0700, "Jeff Strickland" <[email protected]> wrote:

. ."Mike Vandeman" <[email protected]> wrote in message
.news:[email protected]... .> On Fri, 4 Apr 2003 14:43:05 -0800, "Jeff
Strickland" <[email protected]> .wrote: .> .> ."Mike Vandeman" <[email protected]> wrote in message
.> .news:[email protected]... .> .> On 3 Apr 2003 21:30:56 -0800,
[email protected] (Terri Alvillar) wrote: .> .> .> .> .I wonder if any studies have been done to
correlate mountain bike .> .> .equipment shock absorbers and suspension with damage to terrain? Is
.> .> .the damage to terrain commensurate with the level of shock absorbing .> .> .technology on the
vehicle? .> .> .> .> Yes. By Newton's laws of physics, every action has an equal and .opposite .> .>
reaction. In other words, the force applied to the ground (or anything .> .else in .> .> their path,
such as a plant, animal, or person) is identical to the .force .> .> applied to the bike. The reason
that mountain bikes are built much .> .stronger than .> .> normal bikes is that they encounter much
greater FORCES. Therefore, .they .> .apply .> .> much greater forces to the ground & everything else
in their path. QED .> . .> .Technically, a mountain bike with a shock absorber should have less of
an .> .impact than one without a shock absorber. Think of the words being used .> .here, SHOCK
ABSORBER. A shock absorber absorbs shocks, therefore by .> .definition, less of an impact. .> . .>
.Think of the water barrels they (CalTrans or others) place on the .> .impact-side of a sign or
post. The sign or post might weigh more, but the .> .impact upon objects that strike the sign or
post is lessened. In the .world .> .of bikes and dirt, the dirt is the object that constantly
stirkes the .bike .> .(trying to keep the analogy straight), or in other words, the impact of .the
.> .bike striking the ground repeatedly is lessened because of the shock .> .absorber. Newton's Law
does not take into account the affects of external .> .forces, such as a shock absorber. .> .> Oh
sure. Newton's laws don't apply to mountain bikes. That is the funniest .thing .> I have heard in a
long time! Idiot. . .I never said Newton's laws don't apply, what I said is that the simplistic
.application of them omits the affect of the shock absorber.

But you don't know what that effect is. For example, standing still, the suspension is nothing but
ADDED DEAD WEIGHT.
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Tue, 8 Apr 2003 11:57:08 +0100, "Shaun Rimmer" <[email protected]> wrote:

. .Mike Vandeman <[email protected]> wrote in message
.news:[email protected]... . .> .Please, if you wish to take this further,
do study up on suspension .design, .> .action, and especially 'shock absorbers' - they do just what
it says, .that .> .is, 'absorb shock', not absorb it then dish it straight back out into the .>
.ground. .> .> BS. By the laws of physics, they HAVE to apply the force to the ground, .unless .>
they can FLY! . .They take in the sudden shock quickly, and apply it back slowly,

That defies the laws of physics. Both are equal.

with the .effect of reducing localised impact. Suspension does not create greater .damage than no
suspension - quite simple really, or did you not read the .implications in the original question,
and follow the subsequent information .and thread logically?

It adds greater weight, hence greater force on the ground (vertically & horizontally, since they are
also ridden faster).

.Shaun aRe - Heheheheh - silly question..... .

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Tue, 08 Apr 2003 12:30:00 -0400, "Captain Dondo" <[email protected]> wrote:

.On Tue, 08 Apr 2003 08:58:18 +0000, Terri Alvillar wrote: . .> So it seems the greater shock
absorbing system on a mountain bike, the .> greater damage is possible because one can travel at
greater speeds and .> displace more surface material when braking, skidding, and accelerating. .>
Terri Alvillar .> http://homepage.mac.com/terrialvillar/mountainbikedamage/PhotoAlbum11.html . .I
love these physics arguments. They are so unproductive.... . .OK, soil fails not because of FORCE,
but because of PRESSURE. Two .completely different concepts. (Look it up in any soils book; the
bearing .capacity of soil is in force/area, not force.) . .Pressure is always equal to the pressure
in one's tires.

So if you let all the air out of your tires, you bike will put ZERO pressure on the ground. BS.

Exceed that, you .get snakebite punctures. . .Granted, there are dynamics in play like erosion,
liquefaction, and who .knows what else, but the fact remains that there is no neat, clear answer.
. No need to argue about suspension or anything else.

You missed the point: suspension adds weight, & hence greater pressure on the ground.

.As to what is worse, who knows? Ultimately, does it matter? . .Trails will be built, maintained,
and used. If you're against it, get .over it, cooperate and you'll get a lot more achieved. . .BTW,
Terri, I looked at your site, and the "illegal" trail. Looks like a .well-maintained trail in a
recreational area. It seems to me that if it .was illegal, surely your local Soils Conservation
folks - or whoever has .jurisdiction over soil disturbing activities - would have taken .enforcement
action, no? . .Certainly, "thousands of cubic yards" of excavation is a major project .that would
involve hundreds of dump truck loads, excavators, and large .backhoes. Not something one does "just
for fun". It would also have to .be permitted under local laws and under the federal Clean Water
Act. I .can maybe see where a bobcat was used to move a bit of dirt. So, is it .really illegal, or
do you just not like it? Or are you exaggerating the ."thousands of yards" just for fun? Tell the
truth, now. . .-Dondo d
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Tue, 8 Apr 2003 15:25:29 -0700, "Jeff Strickland" <[email protected]> wrote:

. ."Terri Alvillar" <[email protected]> wrote in message
.news:[email protected]... .> "Jeff Strickland" <[email protected]>
wrote in message .news:<[email protected]>... .> > "Mike Vandeman"
<[email protected]> wrote in message .> > news:[email protected]... .> >
> On 3 Apr 2003 21:30:56 -0800, [email protected] (Terri Alvillar) wrote: .> > > .> > > .I wonder if
any studies have been done to correlate mountain bike .> > > .equipment shock absorbers and
suspension with damage to terrain? Is .> > > .the damage to terrain commensurate with the level of
shock absorbing .> > > .technology on the vehicle? .> > > .> > > Yes. By Newton's laws of physics,
every action has an equal and .opposite .> > > reaction. In other words, the force applied to the
ground (or anything .> > else in .> > > their path, such as a plant, animal, or person) is identical
to the .force .> > > applied to the bike. The reason that mountain bikes are built much .> >
stronger than .> > > normal bikes is that they encounter much greater FORCES. Therefore, .they .> >
apply .> > > much greater forces to the ground & everything else in their path. QED .> > .> >
Technically, a mountain bike with a shock absorber should have less of .an .> > impact than one
without a shock absorber. Think of the words being used .> > here, SHOCK ABSORBER. A shock absorber
absorbs shocks, therefore by .> > definition, less of an impact. .> > .> > Think of the water
barrels they (CalTrans or others) place on the .> > impact-side of a sign or post. The sign or post
might weigh more, but .the .> > impact upon objects that strike the sign or post is lessened. In the
.world .> > of bikes and dirt, the dirt is the object that constantly stirkes the .bike .> > (trying
to keep the analogy straight), or in other words, the impact of .the .> > bike striking the ground
repeatedly is lessened because of the shock .> > absorber. Newton's Law does not take into account
the affects of .external .> > forces, such as a shock absorber. .> .> .> So it seems the greater
shock absorbing system on a mountain bike, the .> greater damage is possible because one can travel
at greater speeds .> and displace more surface material when braking, skidding, and .> accelerating.
. .Technically, a bike with greater shock absorbing ability will do less .damage. Consider the
facts, if you dare. A bike is a moving object, and the .impact each time it touches anything is
either directed at the point of .impact if no shock absorbsion system, or is spread across a wide
area if .there is a shock absorbsion system. If a tire is impacting the ground, and .there is a
shock, then the impact is very slight at the point of impact, and .is gradually spread over a wide
area. Try as hard as a rider might, a shock .will lessen the burden of impact, that is the whole
point of having one.

Pure hogwash. If a suspension bike is standing still, it already has greater impact, because it is
heavier. So it also has greater impact when ridden. Which would you rather get hit by -- a regular,
or suspension bike? Obviously, the former, which is much LIGHTER! DUH!
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Peterh]

Mike Vandeman wrote:

>
>But you don't know what that effect is. For example, standing still, the suspension is nothing but
>ADDED DEAD WEIGHT.
>
>
>
This thread concerned, at one time, the effects of an activity. F=MA

Dead weight does not enter that rather straightforward equation.

Pete H

--
The best thing to do with a stupid remark is to not hear it.
R. Heinlein

 

[Mike Vandeman]

On Mon, 7 Apr 2003 21:40:46 +1200, "Westie" <[email protected]> wrote:

. ."Mike Vandeman" <[email protected]> wrote in message
.news:[email protected]... .> On Sun, 6 Apr 2003 22:35:17 +1200, "Westie"
<[email protected]> .wrote: .<snip> .> .> .> .> BS. By the laws of physics, they HAVE to
apply the force to the ground, .> .unless .> .> they can FLY! .> . .> .And since you know so much
about physics, you will realise that the .> .compression and rebound of the suspension spreads the
forces involved out .> .over a longer period of time (and thereby a longer piece of trail). The .>
.result is that a short, sharp jolt on a tiny piece of trail becomes a .more .> .gentle pressure
over a longer period of time over a longer piece of .trail. .> .Like hitting something with a big
pillow instead of a hammer. .> .> BS. There's no way to avoid hitting the ground with the full force
of the .bike + .> rider's weight, PLUS any momentum due the way the bike is ridden. .> .> Anyway, .>
.what's your point? .> .> === .> I am working on creating wildlife habitat that is off-limits to .>
humans ("pure habitat"). Want to help? (I spent the previous 8 .> years fighting auto dependence and
road construction.) .> .> http://home.pacbell.net/mjvande . .No need to swear. .You are correct. The
bike DOES hit with full force. But, as I explained, .the impact is spread across a wider area and
period of time with suspension. .As others have also said, the total force remains the same but the
force on .any particular piece of trail is less.

So the force of gravity is less in some places? What hogwash!

It's not BS, it's pretty basic .physics. .Anyway, momentum is not PLUS. It's already part of the
force that hits the .ground. I suggest that you stick to arguing about something you know .because
you obvious don't know anything about what is basically high school .physics.

I got straight As in Honors Physics from the greatest University in the world (especially in
physics) -- U.C. Berkeley. It's more likely that YOU don't know what you are talking about.
===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Mon, 07 Apr 2003 05:48:33 -0400, PeterH <[email protected]> wrote:

.Mike Vandeman wrote: . .> hitting the ground with the full force of the bike + .>rider's weight, .>
.This phrase is totally meaningless unless actual mesurements are given. .A mountain bike a rest is
sitting there "with full force." . .>PLUS any momentum due the way the bike is ridden. .> .> .> .>
.So! It might appear that the manner in which the bike is ridden is, .after all, a variable. That's
something dozens of posters have tried to .get across to you.

Right. And suspension bikes allow the rider to go faster, hence hit the trail with greater
force. DUH!

.Pete H

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande

 

[Mike Vandeman]

On Tue, 08 Apr 2003 19:00:14 -0400, PeterH <[email protected]> wrote:

.Terri Alvillar wrote: . .>I think Pete H has just violated the monster ego ordinance. Did you mean
semantics? .>Terri Alvillar .> .> .My monster's ego is quite modest. He has bitten only three
Seventh Day .Adventists and one Democrat in the last year.

Did you say something?

.Pete H

===
I am working on creating wildlife habitat that is off-limits to humans ("pure habitat"). Want to
help? (I spent the previous 8 years fighting auto dependence and road construction.)

http://home.pacbell.net/mjvande