MTB VS Moto: Which Is Greener?

Dirt Biking
Photo Credit.

When compared to its close cousin road biking, mountain biking is not really a "green" sport. We mountain bikers drive our gas-burning cars to the trailhead whenever we ride, and we often travel great distances just to  pedal down new trails.

However, in comparison to its other close cousin, dirt biking, mountain biking appears to be a much, much greener sport! Mountain bikes cause astronomically less damage to the trails, don't burn any gasoline when they're driven, and only require a small vehicle to transport them to the trails.

Fat_Billy put this issue in sharp perspective for us over on the Singletracks forum:

Green? Mountain Biking is very green. My previous hobby was motocross after a previous stint at mountain bike addiction. Motorcross= large vehicle with crummy miledge numbers, motorcycle using leaded race fuel, gas powered pressure washer to clean said motorcycle, most motocross tracks consist of over 100 mile round trip in previous mentioned crummy economy vehicle. Mountain Biking= 4 cylinder economy vehicle to haul bike and self to riding area, nearest riding area is 5 miles round trip. Not much of a comparison on which is greener. Sorta tired of hearing about the oil shortage when we have enough but we aren't allowed to get it. During WWII the Germans didn't have any oil in the later parts of the war but they made Synthetic fuel and oil. Did they know more in 1945 than we do now? Think not. Mountain biking is as green as any sport than requires any transport. Gonna go lube my chain now! Later,

Thanks for putting that in perspective for us man!

A wet dirt bike trail in
the process of being
torn up.
Photo Credit.

Trail Damage
He has really exposed the heart of the issue surrounding transportation and the consummation of fossil fuels, but relative damage to the trails is a very important issue as well. To do this, let's examine the output in horsepower of each machine.

According to an article on Horsepower on Wikipedia, "A healthy human can produce about 1.2 hp briefly (and sustain about 0.1 hp indefinitely; trained athletes can manage up to about 2.5 hp briefly and 0.3 hp for a period of several hours." According to this detailed text on the physics of human power output and the mechanical advantage of gears on a bicycle, "Most recreational cyclists generate about 0.35 hp for a sustained (2 hour) ride. "

These sources agree: the average mountain biker probably puts out about 1/3 of a horsepower on average.

But what about a dirt bike?

The actual horsepower depends on the engine in the individual bike, its age, displacement, and several other factors. In response to a question asked on the topic, most respondents replied that more information was needed, but several gave ranges that could be expected, depend on the bike. One user answered: "Depending on the brand, model, year and modifications you could expect anywhere from 15 to 40. A Chinese bike would be low on power, but a Yamaha factory bike could have closer to 50hp."

Evidence for a broad range of horsepower outputs is corroborated by many, many online sources. This article from 2004, for instance, cites bikes that put out 27-33 horsepower.

Let's compare: a human can put out about 1 horsepower during a vigorous effort, and a dirt bike in roughly the middle of the range can produce about 30 horsepower. That is 30 times the amount of power that human can generate!


Not only that, but dirt bikes are also much heavier machines, and the amount of power is unlimited. Since a human can only put out 0.3 HP consistently, we're talking closer to 100 times the amount of power as a human... at least. For a bike with 40 or 50 HP, that number is even higher!

Don't believe me? Check out the video below of a race between a dirt bike and a downhill mountain biker. Notice the dirt rooster tails the dirt bike sends up, and how it is constantly tearing up the trail in the turns and on the climbs. Then compare the effects of the mountain bike:



Montana
What really jerks my chain is that when the Bozeman area lost mountain bike access to many of their epic trails, the environmentalist prosecutors essentially equated mountain bikes with dirt bikes, and claimed that their effects were almost exactly the same. As any rational person can see from the evidence above, this is just not the case!

Access to those trails was lost on completely false pretenses. Mountain biking is a much greener and much, much lower impact sport than dirt biking is or ever will be!

Your Turn: Please write your thoughts and opinions in the comments section below.