Frequently Asked Questions about Mountain Biking


Mike Vandeman

Frequently Asked Questions about Mountain Biking
Michael Vandeman, Ph.D.
Updated October 16, 2007

1. Why do people mountain bike?
a. They say that using a bike allows them to get much farther, in
the same amount of time, than they can by walking. They also maintain
constant pressure on land managers, to open more and more trails to
bikes. Of course, all of these trails are already open to them, if
they choose to walk. They also frequently claim that closing trails to
bikes "excludes" them from the parks. This could only be true if they
were unable to walk. Of course, they are able to walk. There's nothing
inherently wrong with bicycling instead of walking; we all like to
save energy, when it's appropriate. Use of a bicycle to replace
automobile use is obviously beneficial. However, by the same token,
replacing hiking with mountain biking is obviously not beneficial.
b. They are interested in the quantity of nature they can see,
rather than the quality of their experience. While riding a bike,
especially over terrain as rough as a trail, one has to be constantly
paying attention to not crashing. That makes it almost impossible to
notice much else. By contrast, a hiker feels the ground, hears all the
sounds and smells all the odors of nature and can stop instantly, if
he/she finds something interesting. The brain thrives on stimulation.
A biker has to travel several times as far as a hiker, to get the same
stimulation as a hiker. (And, by the same token, motorcyclists have to
travel several times as far as a bicyclist, and an auto user several
times as far as a motorcyclist, since they are enclosed in a metal
c. They are interested in thrills. Riding a bike on a trail,
especially a trail containing many obstacles, or a trail one is not
familiar with, is very challenging. (But if mountain biking is the
high point of your week, as it seems to be for many mountain bikers,
you must be leading a pretty dull life, off of the bike!)
d. They are interested in building mountain biking skills and
competing with other mountain bikers. The thrill of racing drives
people to spend more money on their bike, and ride it harder and more
often. Racing, up to and including the Olympics, drives a lot of
mountain biking. Of course, it is also extremely harmful to the parks
and natural areas that are used for practice! It is hard to think of
any other (legal) use of public lands, other than hunting, that is as
harmful as mountain biking.
e. They want to get to their destination faster (not considering
that the process of getting there is a major part of the enjoyment).
Once, when much younger, I was hiking along a very boring trail. The
thought came to me that if I had a bike, I could get past the boring
section of the trail, and to the interesting part much faster. But
about 2 seconds later I realized that if I could do that, so could
everyone else, and the place would be full of people and ruined. That
was the end of my (2-second) mountain biking career.

2. What is driving the sport of mountain biking? Besides the
attraction for participants, manufacturers and retailers of mountain
bikes and mountain biking accessories, as well as "adventure" travel
guides, make a lot of money from promoting mountain biking. Even some
auto manufacturers (e.g. Subaru) promote and sponsor mountain biking,
and try to use its popularity to sell more cars. The tourism industry
also promotes mountain biking, among other attractions.

3. What harm does mountain biking do?
a. Most obvious is the acceleration of erosion. Knobby tires rip
into the soil, loosening it and allowing rain to wash it away. They
also create V-shaped grooves that make walking difficult or even
dangerous. The mechanical advantage given by the gears and ball
bearings allow a mountain biker to travel several times as fast as a
hiker. Given their increased weight (rider plus bike), this results in
vastly increased momentum, and hence much greater horizontal
(shearing) forces on the soil. (Witness the skid marks from stops,
starts, and turns.) According to Newton, every action has an equal and
opposite reaction. Mountain bikes were built much stronger than other
bikes, so that they could withstand the greater forces they were
subject to on rough trails. These same forces, therefore, are being
applied to the trails! To give a definite number, the winner of a
20-mile race here in Briones Regional Park averaged 13 MPH (the speed
limit is 15 MPH -- where were the park rangers?).
b. A hiker must be very careful not to accidentally step on small
animals and plants on the trail. For a mountain biker, it is almost
impossible to avoid killing countless animals and plants on and under
the trail. They have to pay attention to controlling the bike, and
can't afford to look carefully at what is on the trail, especially
when travelling fast. And even if they happen to see, for example, a
snake, it is hard for them to stop in time to avoid killing it. A
hiker, when crossing a creek, will try to avoid getting wet, by
crossing on stepping stones or logs. Mountain bikers, on the other
hand, simply ride right through the creek bed, crushing any animals or
plants that happen to be there. Mountain biking magazines are full of
photos of mountain bikers throwing up spray, as they barrel through
creeks. Not only do bikes destroy animals and plants as they ride
across streams, they ride through streams stirring up sediment. The
sediment in the water interferes with the oxygen uptake by aquatic
life, for example, killing fish- and frog eggs. Young fish, insects,
amphibians, and aquatic microorganisms are extremely sensitive to
sediment in water.
c. Bikes also allow people to travel several times as far as a
hiker. This translates into several times the impacts, both on the
trail and on the wildlife (to say nothing of the other trail users).
Existing parklands are already inadequate to protect the wildlife that
live there. When they are crisscrossed by mountain bikers and legal or
illegal trails, their habitat becomes even more inadequate. Mountain
bikers frequently advertise rides of 20-50 miles or more. Have you
ever tried to walk that far in a day? In other words, allowing bikes
in a park greatly increases human presence in that park and drives
wildlife further from the resources that they need to survive,
including water, food, and mates.
d. Due to their width and speed, bikes can't safely pass each
other on narrow trails. Therefore, policies that permit mountain
biking also result in more habitat destruction, as trails are widened
by bikers (or by hikers and equestrians jumping out of their way).
e. Knobby mountain bike tires are ideal for carrying mud, and
consequently exotic plants, fungi, and other organisms from place to
place, resulting in the spread of exotic invasive species, such as
weeds and Sudden Oak Death.
f. Mountain biking is driving the very young and old off of the
trails and hence out of the parks. Even able-bodied hikers and
equestrians fear for their safety, and don't enjoy sharing the trails
with bikes. (The mountain bikers claim that they are simply being
selfish and "unwilling to share", but actually they have no problem
sharing trails with mountain bikers; it is only their bikes that are a
g. Mountain bikes, which are obviously built to go anywhere,
teach children and anyone else who sees them that the rough treatment
of nature is acceptable. This undoubtedly has a negative effect on
people's treatment of nature.
h. In order to mitigate bike-caused erosion, park managers have
been resorting to extreme measures -- even in some cases putting a
plastic matrix or other exotic material under the trail (e.g. in
Pleasanton Ridge Regional Preserve, near Pleasanton, California)! It's
hard to imagine that this will have a beneficial effect on the park
and its wildlife….
i. Allowing mountain bikes in a park greatly increases the damage
to the trails, damage from "bootleg" (illegally created) trails, and
the problems of conflicts between trail users, and hence the cost of
maintaining the park. Considering how tight park budgets are, we can't
afford the extra costs of policing, and repairing the damage from,
mountain biking.
j. For the science on mountain biking and its impacts on wildlife
and people, see

4. Mountain bikers claim that their sport has no greater environmental
impact than hiking. Is that true?
a.If you read the "studies" that make that claim, you find that they
don't really compare the impacts of hiking and mountain biking, but
only the impacts per foot. If, for a moment, we assume that the
studies are correct in their having equivalent impacts per foot, it
would still follow that mountain biking has far greater impact per
person, since mountain bikers typically travel so much farther than
hikers. Besides overlooking distances travelled, those "studies"
almost all ignore impacts on wildlife. And they don't study mountain
biking under normal conditions -- only at a very slow speed. Actually,
the comparison with hiking is irrelevant. It would only be relevant if
we planned to allow only one of the two, and were considering which of
the two is more harmful. In fact, no one is considering banning
hiking. We are only considering adding mountain biking. Therefore, the
only relevant question is, "Is mountain biking harmful"? (Of course,
it is!) There is only one truly scientific study that I know of that
compares the impacts of hiking and mountain biking. It found that
mountain biking has a greater impact on elk than hiking (Wisdom, M.
J., H. K. Preisler, N. J. Cimon, B. K. Johnson. 2004. Effects of
Off-Road Recreation on Mule Deer and Elk. Transactions of the North
American Wildlife and Natural Resource Conference 69, 2004,
pp.531-550.) See
b. On its web site, IMBA mentions recent research on mountain
biking by Dave White et al and Jeff Marion, both of whom claim that
mountain biking and hiking have "similar" impacts. Is that true?
First, "similar" is not a scientific term and really has no clear
meaning. That term is being used only to obfuscate. Second, these are
survey studies, not experimental studies. By its very nature, a survey
study cannot be used to compare the impacts from two activities,
because it doesn't control all the variables. For example, we don't
know if the differences in erosion between two trails are due to the
mountain biking vs. hiking use, or due to differences in the weather,
terrain, steepness, soil type, management practices, amount of use,
hikers on the "mountain biking trail", mountain bikers on the "hiking
trail", etc. White et al only measured their trails once, and didn't
even collect any data on hiking impacts! See and
c. Why would a researcher risk his/her reputation by doing
such shoddy work? For money! And to ensure the continuance of their
sport. If land managers think that mountain biking is more harmful
than hiking, they will be more likely to close trails to bikes. Bike
parts manufacturer Shimano paid Professor White to do his study.
Research funds are difficult to obtain. A researcher who can be relied
upon to produce research favorable to mountain biking will be able to
obtain funding from the mountain biking industry. A researcher who
tells the truth about mountain biking won't be able to obtain research
funds and will risk stunting his/her career.

5. Where should mountain biking allowed? A couple of role models for
wildlife protection are Yosemite National Park and East Bay Municipal
Utility District (in Alameda and Contra Costa counties, California).
They both restrict bicycles to paved roads, where they can't do much
harm. Somehow bicyclists have managed to enjoy their sport for over a
hundred years, without riding off-road.

6. What should the policy be on trails? Closed to bikes, unless marked
open. Signs that say "No Bikes" are quickly and repeatedly ripped out
of the ground by mountain bikers.

7. Isn't it discriminatory to allow hikers and equestrians on trails,
but not mountain bikers? Mountain bikers love to say this, apparently
because they think it will gain them some sympathy. The truth is that
mountain bikers have exactly the same access to trails that everyone
else has! It is only their bikes that are banned. If mountain bikers
were really being discriminated against, they could easily go to court
to gain access. However … they already have access to every trail in
the world!

8. Don't I have a right to mountain bike on all public lands? I am a
taxpayer! The public has the right, through its elected
representatives, to restrict how land is used. A federal court has
already ruled that there is no right to mountain bike. It is a
privilege, and any land manager who gives a good reason (such as
safety or protecting the environment) can keep bikes off of trails

9. Don't mountain bikers do some good things, like trail construction
and trail maintenance? Trail construction destroys wildlife habitat
both directly (by killing plants and animals) and indirectly (by
reducing the size of the intervening "islands" of habitat). Moreover,
mountain bikers favor trails that are "twisty" (sinuous), bumpy, and
full of obstacles that provide thrills for mountain bikers. Such
designs increase habitat destruction (by lengthening the trail) and
make the trails less useful for hikers and equestrians. Trail
maintenance sounds good, until you realize that it would hardly be
necessary, if bikes weren't allowed there. The mountain bikers are the
main reason why trail maintenance is necessary! Trails used only by
hikers require hardly any maintenance. Therefore, admitting bicycles
to a park greatly increases its cost of maintenance. Nothing is really
"free", including trail construction and maintenance. (How does the
saying go? "Beware of Trojans bearing gifts"?)

10. But don't mountain bikers provide added safety, by being able to
quickly summon help in the event of an emergency? I would rather trust
in a cell phone, than a speeding mountain biker. Besides, natural
areas are already one of the safest places you can be. In over 50
years of hiking and backpacking, I have never witnessed any situation
requiring emergency aid. Most people go to natural areas partly for
solitude. If we wanted to be around large, fast-moving pieces of
machinery, we would stay in the city!

11. Can't mountain biking help get our overweight kids off the couch?
Hiking can already do that, without causing extra harm to wildlife and
people. Mountain biking downhill provides zero exercise benefit.
Mountain biking on level ground provides minimal exercise benefit,
much less than walking. Since it's impossible to pay any attention to
your surroundings while mountain biking (or you will crash), there's
no reason to promote mountain biking. It benefits only those who stand
to make money off of it, such as bike manufacturers, retailers, and
tour companies. Mountain biking is also inappropriate for young people
because it's very expensive!

"Fri, Aug 10 2007:
Newsgroups: alt.mountain-bike
From: Ride-A-Lot <[email protected]>
Date: Fri, 10 Aug 2007
Subject: Re: need suggestions on mountain bike, thanks a lot
Any bike you buy from a big box store (i.e. Target, Wal-Mart, Dicks,
Sports Authority, etc.) is going to be JUNK. If you ware going to do
any actual mountain biking, you will very very disappointed with the
performance. For a new mountain bike, the low-end entry level bike
Specialized Rockhopper is one) will cost around $500."

(Mountain bikes are built tough because street bikes can't take the
pounding that they would get on trails. They would fall apart.)

12. But isn't mountain biking healthful exercise? No! Mountain biking
is inherently dangerous, and cannot be made safe. Hiking trails are
not designed for bicycling. They are unpredictable. There is a reason
why departments of transportation have standards for bicycle trails
that require a smooth surface, not too steep a grade, a no-skid
surface, a minimum width, a long sight distance (no blind turns), etc.
Mountain bikers regularly fall off their bikes, resulting in
paraplegia, quadriplegia, or even death. This obviously cancels out
any possible health benefit. See

13. Doesn't mountain biking get people out of their cars? So do
walking, road cycling, and transit use, without harm to the natural
environment. Since very few mountain biking opportunities are within
easy bicycling distance, the vast majority of mountain bike trips
require transporting the bike in a truck, SUV, or car. If mountain
bikers cared about the environment, they would bicycle to the park,
lock their bike at the trailhead, and hike. Or simply bicycle on paved
roads, as bicyclists have for the past century.

14. Doesn't the threat from mountain biking pale, in comparison to
other sources of environmental damage, such as logging? Maybe, and
maybe not. Mountain biking teaches people that the rough treatment of
nature is acceptable, so it may lead to many other abuses. In parks,
where most mountain biking is done, it is probably the most harmful
activity allowed. But even if mountain biking is less damaging than
another activity, such as logging, it is still additional damage. If
an area is already messed up (e.g. by logging), how does that make it
okay to do additional damage? It doesn't!

15. What's wrong with night riding? Humans have been destroying
wildlife habitat for centuries, so that very little remains. Our
presence in parks prevents wildlife from using a large part of their
habitat, at least during the daytime. Now that night riding is
becoming popular, wildlife and being denied that habitat even at
night, or incur an increased risk getting run over, if they attempt to
use it. There is very little law enforcement even during the day in
these days of tight budgets. There is no patrolling of parks at night!
This gives mountain bikers free rein to do whatever they want,
including riding trails that are closed to bikes or even building
their own illegal trails. No wonder night riding is so popular! And,
of course, night riding makes an activity that is already very
dangerous, much more dangerous.

16. Don't the vast majority of mountain bikers ride responsibly?
Actually, just the opposite is true. In a scientific study that IMBA
had on their website for a while, then quietly removed, 83.1% of
mountain bikers broke the law (see

17. Aren't the problems with mountain biking just caused by "a few bad
apples"? There aren't just a few! There are enough to put some in just
about every park in the world. The same problems appear everywhere:
riding off-trail, riding where prohibited, illegal trail construction,
excessive speed, accelerating erosion, killing plants and animals on
and next to the trail, driving other trail users off the trails, etc.

Note: I was the Chair of the Wildlife Committee of the Sierra Club's
San Francisco Bay Area Chapter for a decade. During the same period, I
studied conservation biology and the environmental impacts of mountain
biking, which are summarized in my paper "The Impacts of Mountain
Biking on Wildlife and People -- A Review of the Literature":

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.)

Please don't put a cell phone next to any part of your body that you are fond of!
Nice collection of material once again, I notice it is all summaries
of other's peoples former papers and none provided by you at all,
which is what we all expected. Please extend our thanks to all the
parties that shared the info and attempted to do the research except
Sierra Club or the profit generated Company that supplies China made
products, therefore encouaging the breakdown of nature.

Mike Vandeman

On Wed, 27 Feb 2008 23:06:50 -0800 (PST), "[email protected]"
<[email protected]> wrote:

>Nice collection of material once again, I notice it is all summaries
>of other's peoples former papers and none provided by you at all,
>which is what we all expected. Please extend our thanks to all the
>parties that shared the info and attempted to do the research except
>Sierra Club or the profit generated Company that supplies China made
>products, therefore encouaging the breakdown of nature.

Did you say something?
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.)

Please don't put a cell phone next to any part of your body that you are fond of!

Mike Vandeman

On Fri, 29 Feb 2008 11:38:03 -0800 (PST), "[email protected]"
<[email protected]> wrote:

>> Did you say something?
>> --

>As usual, you know I did, you read all my posts you draft dodger!!

Don't flatter yourself. I already know you NEVER say anything (valid).
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.)

Please don't put a cell phone next to any part of your body that you are fond of!