I just came across a fascinating piece on Oregon Public Radio’s EarthFix site, in which author Ashley Ahearn, a rider herself, discussed motorcycle noise in National Parks with Karen Trevino of the NPS Natural Sounds and Night Skies Division.  

Trevino notes that most of the excessive noise on roads comes from bikes with aftermarket exhaust parts, while the vast majority of motorcycles pose no special noise problems.  Ahearn’s bike “sounds like a Singer sewing machine,” according to one of the enhance Harley owners that the author talked to outside a biker bar near Mount Rainier National Park.  That may be what Trevino and her NPS cohorts wish all bikes sounded like, but that’s not the case.  In the video below, the NPS charted the sound footprint of a single motorcycle traveling along the Going to the Sun Road in Glacier National Park; the Park Service has found that bikes can be heard up to 18 miles away in some situations.

MotorcycleNoiseVid from EarthFix on Vimeo.

Trevino says that while the NPS is gathering data, there are no plans to impose restrictions on motorcycles in National Parks.  Rather, the NPS is partnering with motorcycle associations to ask riders to stay in smaller groups, not accelerate excessively and respect parks’ quiet hours.