A Comparison of Environmental Impacts from Mountain Bicycles, Class 1 Electric Mountain Bicycles, and Motorcycles

Abstract

In the fall of 2015, under contract with the Bicycle Product Suppliers Association (BPSA), with counsel from a field of recreation management experts, and through a review of existing studies of erosional impacts from trail users, the International Mountain Bicycling Association (IMBA) conducted a scientifically controlled field study designed to measure relative levels of soil displacement and erosion resulting from traditional mountain bicycles, electric mountain
bicycles (eMTBs), and traditional off-road motorcycles (i.e. dirt bikes). The observations were compiled in controlled environmental conditions, with each type of bike making multiple passes on separated sections of the same trail within a single test site.

IMBA developed these hypotheses for this small initial study:
• Soil displacement and erosion caused by mountain biking will be consistent with existing
studies showing relatively low impact as with other types of non-motorized travel on this
type trail (a bike-optimized trail also considered a sustainable trail) and this set of local
conditions.
• Soil displacement and erosion from Class 1 eMTBs will likely fall somewhere between
those caused by mountain bikes and motorcycles. It is expected that they will much more
closely resemble those of mountain bikes.
• It is expected that Class 1 eMTBs may lead to greater soil displacement under certain
conditions, such as through turns, including bermed turns; on ascents and descents; and
where there are abrupt changes in trail conditions.

Results from the field experiment show that, under this set of conditions, soil displacement and tread disturbance from Class 1 eMTBs1 and traditional mountain bikes were not significantly different, and both were much less than those associated with a gasoline-powered motorcycle. Understanding the potential resource impacts of trail-based recreation is a necessary and important first step for formulating management strategies. This is especially important for new
types of recreational pursuits, such as the fast emerging power-assisted vehicles like eMTBs. Additional research is needed to further assess the range of environmental and social impacts for
successful eMTB use on public lands.

Mountain bicycling is a solely muscle-powered activity, and is thus regulated as a non-motorized
use, along with hiking, trail running, and horseback riding. eMTBs are not entirely muscle powered. IMBA recognizes that eMTBs, particularly Class 1 eMTBs, are substantially different from other motorized uses, and may warrant a separate category and new management strategies. IMBA does not have an advocacy interest in this Class 1 eMTB study, but is leading this study as a respected partner of land management agencies; to further knowledge about recreational
trails; and to inform future discussions with members, chapters, land mangers, the bike industry, and other user groups.