Mountain Bike Pedal Strike Caused Wildfire Near Mammoth

Blaze was sparked by metal against rock, fire investigators conclude; the internet thinks the Forest Service hates bikes.

Things are dry in the Eastern Sierra, really dry. So dry that all it took to begin a wildfire on August 5 along the Lower Rock Creek singletrack trail north of Bishop and south of Mammoth was a mountain bike pedal cracking against a rock and sending a spark into the underbrush.

The fire occurred three weeks ago and caused the evacuation of a small, nearby community and the closure of a road. By the time it was contained and put out, the fire burned 122 acres.

“The cause of the Rock Creek fire that started on August 5th has been determined,” Inyo National Forest posted on Facebook. “Investigators have concluded that the fire was started from a bicycle pedal strike to a rock. Conclusive evidence was found in the fire origin area that was on the Lower Rock Creek mountain bike trail. A fire ignition from this type of trigger is a testament to how dry the area is right now. All residents and visitors are asked to be extremely careful with anything that may cause a fire while you are out in the forest.”

Lower Rock Creek is the premium mountain biking singletrack in the Eastern Sierra, rated number one by readers of MTB Project. It parallels U.S. 395 between Bishop and Mammoth, but feels like a world away as you’re down in the creek drainage, slaloming between ponderosas and sage.

Forest Service fire prevention technician Kirstie Butler, who rides Lower Rock Creek herself, said that the ignition point was found unequivocally down to the actual rock the pedal struck and the patch of cheatgrass that caught the spark and was set ablaze.

“It really doesn’t take much for cheatgrass to ignite. Anything could start a fire in conditions like this. It would have been like striking a flint,” Butler told Bike Radar.

Apparently, the internet knows more about the cause of wildfires than a U.S. Forest Service fire prevention technician, because the condemnation on the Inyo National Forest Facebook page was swift and unrelenting, with more than 100 comments accusing the Forest Service of anti-bike bias, stupidity, and, perhaps, sorcery.

Okay, that last one I made up. But still. Our little world has become so politicized that people see evidence of prejudice in bad luck and science.

“This is not about pointing fingers,” said Butler. “We know it wasn’t done maliciously. We understand that mountain biking is a popular activity and we’re not trying to say that this is a reason to stop. It’s just something to be aware of.”

Photo by Andre Bessa


Steve Casimiro is the editor of Adventure Journal. Follow him on Instagram at @stevecasimiro.
Showing 7 comments
  • JJ

    Up Next: Hiker flatulence causes forest fire.

  • Mikie Watson

    I caught wind of this on my own Forum, here in Southern California. I too instantly gravitated to the improbability of pedal strike as the cause. I travel North on the 395 every year to hit up Lower Rock Creek Trail. The sport of mountain biking gets beat up often by other trail groups so I think that it’s easy for mountain bikers to instantly get cynical.

    Although I’m pretty confident it was NOT sorcery, I am curious as to what the combination was that made the spark. Magnesium is often used in crank arms which is potential and I’m not sure aluminum can cause a spark. Are there anymore details? Is LRCT closed? I will be up there for my annual ride mid month of September.

    The Adventure Journal is a nice find.

    Thanks for the story

  • t.s.

    Shimano spd pedals have a steel cleat interface that can potentially, but very very rarely make a spark. They are pretty much the most common pedal you will find at any given trail head that isn’t a straight up DH trail, or a dirt road/ rail trail where people are riding bicycle shaped objects from walmart. That being said have there been any incidents of horses with metal shoes starting fires? I would think if it was possible that a pedal could create a fire starting spark, a horse would do it much more frequently? But I know really nothing about horses.

    • Pete Roggeman

      Steel pins are used in most flat pedals and I’ve seen them cause sparks on numerous occasions. Hard to see in a sunlit area, but under a forest canopy, or close to dusk, it’s not unusual.

  • ste

    I thought horses had iron shoes? And they ‘strike’ much more than the odd bike pedal strike.

    I bet myth busters could solve this.

  • K

    Been doing the wildland fire thing for a while, not sure people understand how accurate a fire investigation can be, Im talking narrowing the point of origin down to a square foot on a 2000 hectare fire, using macro indicators ect. Then sifting that small area and finding the staples from a book of matches. Unlikely that a pedal would start a fire, but not impossible, and they could easily trace the fire back to the origin.

  • Barry

    Very curious what the “conclusive evidence” is that is “unequivocal”. It would be helpful to help us non-firefighter types to understand. They state a strong case without actually explaining anything.

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