Following a day of trail maintenance in October 2017, members of Mountain Bikers of Santa Cruz (MBOSC) realized that many of their active volunteers also happened to be academics in fields including soil science, geology, and social dynamics.

This realization kicked off a new science committee that conducted a comprehensive analysis of scientific studies on the relationships between nature and recreational trail users, including hikers, equestrians, and mountain bikers. The study focused on hydrology and geology, plants and wildlife, and social issues.

Among their “meta-study” findings:

  • In general, the studies showed no statistically significant difference in soil erosion, excavation, ruts, and trail widening between hiking and biking, and both have less impact than horse riding.
  • On properly built and well-maintained trails, no measurable difference is seen between the relative impacts caused by mountain biker and hiker user groups.
  • User-created trails are unplanned and don’t undergo the rigorous environmental review and design that officially sanctioned trails do.
  • Impacts on wildlife are similar whether the human interaction is with hikers, bikers, or equestrians. Some animals were found to be less disturbed by bikers than other types of trail users.
  • Birds tend to be more adversely affected when users make frequent stops along a trail or when they make more noise.
  • Unsanctioned trails are not isolated to mountain bikers and are often a symptom of an unmet need for legitimate trail options.

In addition, within each topic area, the review lists the best practices that riders can follow to minimize their impact on trails, wildlife, and other trail users.

MBOSC hopes that the Mountain Biking Impact Review helps mountain bikers think about the broader environment in which we practice our sport. We are part of a larger community of trail users and a complex ecosystem that we directly affect. It is important that we understand our impacts and make responsible decisions about how and where we ride.

While this is certainly not the last word on the issues surrounding mountain biking in the wilderness or public lands in general, this report creates a good foundation that trail stewards, local organizations, or even individuals can build upon to create more sustainable relationships with land managers and the general public. Whether you are a trail builder, a land manager, or simply someone who cares about their local trails, give this a read.

# Comments

  • jgmtb

    This impact review is excellent work, thanks for the write-up. It seems like a rigorous study, with sensible take-aways, namely that unsanctioned trails are more damaging. So many studies are one biased; this one has good information on complex topics (like hydrology and geology), which acknowledge an issue, while contextualizing it and providing ways to mitigate the potential damage. Awesome, awesome work, guys.

  • isawtman

    Yeah, A bunch of Mountain Bikers summarizing some studies. Sounds like Bill Barr summarizing the Mueller Report.

    Here’s some actual quotes from some studies about mountain biking impacts:

    Herrero and Herrero (2000)
    “The sudden encounter is the most common situation associated with grizzly bear inflicted injury” (Herrero 1989). Mountain bikers are at particular risk of this type of encounter because the potential speed and relative silence of a biker may facilitate closer proximity to bears before being detected. Schmor (1999) interviewed 41 mountain bikers in the Calgary region who cycled in the Rocky Mountains. The responses indicated that 84% of survey participants had come within 50 m
    of a bear while mountain biking and 66% of the encounters clearly startled the bear. Herrero & Herrero (2000) studied incidence of conflict/interaction between humans and grizzly along the Moraine Lake Highline Trail in Banff National Park. They found that, though intensity of use was much lower for mountain bikers than for hikers along this trail, mountain bikers accounted for a disproportionately high incidence of conflict with bears. Herrero and Herrero (2000) suggest that grizzly bears are more likely to attack if a human is closer than 50 m before being detected. The speed and relative silence of mountain bikes, especially when combined with environmental factors (e.g., dense vegetation, hilly terrain, sound of running water),
    likely contributed to mountain bikers approaching bears closer than 50m before being detected by the bear. Parks Canada instituted a requirement to travel in tight groups of at least six, which has reduced human-bear conflict in the area (Simic 2007).

    T Wohrstein (1998)
    Clearly where possible, mountain-bike-specific trails should be
    established to avoid conflicts with other trail users

    Knight and Taylor (2003)
    While Taylor and Knight found no biological justification for managing mountain biking any differently than hiking, they note that bikers cover more ground in a given time period than hikers and thus can potentially disturb more wildlife per unit time.

    • bitterroot

      isawtman perhaps you would like to share a link the the Wohrstein article or book. The only reference I can find is his book in German, ” Mountainbike und Umwelt”. Here are some references to it from “Perception and reality of conflict: walkers and mountain bikes on the Queen Charlotte Track in New Zealand”

      To date there appears to be no evidence of bikes having any more significant impact on important environmental features than other recreation uses (Cessford, 1995a; Woehrstein, 1998; Weir, 2000).

      Despite the general perception otherwise, most available comparative reviews and studies have concluded that while visibly very different, the physical impacts of bikes on tracks were not any worse than those of walkers overall (Keller, 1990; Wilson & Seney, 1994; Chavez et al. 1993; Ruff & Mellors; 1993, Cessford, 1995a; Woehrstein, 1998; Weir, 2000; Thurston & Reader, 2001;).

      If you read further it appears that most opposition to mountain bikes comes from users who have biased opinion on mountain bikes that are are incongruent with reality.

      So bikes may potentially cover more ground that hikers and impact more wildlife per unit time. Presumably this also applies to trail runners.

      No one is arguing that mountain bikes don’t impact wildlife or other users, and no doubt we could get into an argument throwing articles likes back and forth. For some animals bikes have more impact and for other animals hikes have more impact, but overall the impacts balance out to be comparable. I’m not sure why that is controversial.

  • isawtman

    You know what the scam is behind the studies. Mountain bikers can cover 3 times the mileage compared to a hiker. Therefor when these studies use test plots they should have mountain bikers go through the test plots 3 times more than hikers. All of the studies have done the test plots on a 1 to 1 basis.

    • bitterroot

      Your assumption only makes sense in a closed loop scenario where the trail is of finite length and all sections of the trail are used equally by all users and all users are on the trail for the same amount of time. I don’t think this equates to the real world.

      Scenario One: Assume there is a destination at the end of the trail such as a lake. In this case is unlikely that the biker is going to to make laps and go to lake three times. More likely the person on the bikes will be on the trail for 1/3 less time. The impact to the trail from the hiker and biker is the same.

      Scenario Two: The trail system has discrete trailheads and the distance between trailheads is longer than the distance the average hiker covers. In my experience this is the most typical of a real world experience. I would venture that most hikes or strolls are less than one mile and 90% are less than 5 miles. I’ll admit these number are to a degree pulled out of the air, but seem to comport with most peoples experience. Since most trails tend to be longer than this, at least where I am, the impact is spread over a larger trail volume of trail for bikers relative to hikers so that any single meter of trail is not getting three time the impact.

      Scenario Three: Heavily used urban trails where hikers and bikers use every section of the trail equally and they spend the exact same amount of time on the trail. Possibly somewhere in more populated areas this might apply, but in these cases the trails are probably hammered regardless of the users group.

      As far as impacts on animals due to the bikes traveling the assumed three times faster. It is harder to tease out which has more impact. Presumably for critters that are relatively stationary and In close proximity to the trail, they will encounter more bikers, but for briefer duration. Whether more but more temporary encounters or fewer but longer encounters cause more stress is highly species dependent. For other animals the learn to avoid the predictable use of trails and are more stressed by unpredictable encounters with people off trail, something that happens more with pedestrian users such as birders, hunters, etc.

      In the end making across the board statements that bikers are worse doesn’t seem to be consistent with the literature. It is highly site specific depending on the local wildlife populations, trail design, and trail surface.

  • isawtman

    My comment make sense everywhere. Mountain bikers go at a rate that is 3 times as fast as a hiker. Therefor, if they are doing the same amount of damage in test plots with the same number of passes, well, then they are doing 3 times as much damage in real life.

    And all of your scenarios are stupid. You say in number 1 that: “Assume there is a destination at the end of the trail such as a lake. In this case is unlikely that the biker is going to to make laps and go to lake three times. More likely the person on the bikes will be on the trail for 1/3 less time. The impact to the trail from the hiker and biker is the same.” No, they are absolutely not the same because the mountain biker will continue mountain biking someplace else with the 2/3 of the time that they have left thereby disturbing more areas. So, your whole premise is absolutely wrong.

    But here’s the situation that absolutely proves that mountain biking is completely different than hiking. In 2017 Brad Treat was mountain biking and he crashed into a bear. Now, bears have charged hikers, that’s true. But when was the last time a hiker was hiking down a trail and crashed into a bear. Never.

    • bitterroot

      Can we please be civil and not insult each other. So explain to me what is stupid about a round trip to a lake that takes 6 hours to hike or 2 hours to bike. (Still assuming your 3:1 ratio, which is debatable, but true for some trail conditions). I find it unlikely that the mountain biker is going to ride another 4 hours. He will either spend more time at the lake fishing or spend more time drinking beer, or drinking beer while fishing. Personal experience – Fuse Lake, Montana.

      As far as 3 times damage in real life. I would compare to homeopathy or the old saying, ” the solution to pollution is dilution.” The impact (not necessarily damage) is dispersed over a larger area of trail. In other words diluted. At some level this damage in sub-threshold and far overwhelmed by natural forces. Anyone who has done even a modicum of trail work knows that the biggest impact on most trails is poor design and erosion from water.

      I have have never argued that that hiking and biking and identical in impacts. They are comparable. An apple is not an orange, but they are still fruits and have similar nutritional value. Maybe a pear and apple would be more appropriate, but hopefully you get the gist. Also in NW Montana. Close encounter at 15 ft while hiking off trail. https://missoulian.com/news/state-and-regional/survivor-recounts-grizzly-bear-attack-in-northwest-montana/article_085503fc-f045-54ac-a3d9-315aa506214f.html

    • bitterroot

      Todd, is that you? I should have known. I’m done debating.

    • isawtman

      Again, Bitteroot, your latest example is totally irrelevant.
      The example is of a couple who were hiking a trail and
      a grizzly bear charged at them. Totally different than
      Brad Treat mountain biking down a trail and CRASHING
      into a bear that just happened to be on the trail.

  • Gdb49

    The fact that we exist means we will have some impact on the planet, we can not expect to do anything without some impact. Isawtman, bikers may cover 3 times the distance, but there are 10 times the number of hikers out on the trails, so maybe you need to have the hikers x 3? The animals out in the woods have an impact also and an occassional run in with wildlife is unavoidable. Ride responsibly, advocate for more professionaly built sactioned trails, be respectful to wildlife and your fellow trail user and we can all enjoy nature. Isawtman do you ride?

    • isawtman

      So, you are making my point for me that these studies are flawed. You also say that “an occassional run in with wildlife is unavoidable” but if you are covering 3 times more ground than hikers, well then you have 3 times as much trail to have an “unavoidable” encounter with wildlife.

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