Along its 3,100 miles that wind from the Canadian border down to Mexico, the Continental Divide Trail is one of the most rugged, and in parts one of the most visually spectacular, hiking trails in the country. Now the U.S. Forest Service says the route could be opened in places to mountain bikes, a move that raises a question or two regarding possible impacts to national parks.

From north to south the trail runs through portions of Glacier, Yellowstone, and Rocky Mountain national parks, as well as El Malpais National Monument in New Mexico. In places you need the skills of a mountain goat to negotiate the route, which, by the way, is not entirely in place.

Early in October the Forest Service published its proposed rule changes to the trail's comprehensive management plan in the Federal Register. They took effect November 4. The updated management plan does not magically open the entire Continental Divide National Scenic Trail to mountain biking, but rather provides "that bicycle use may be allowed on the CDNST if the use is consistent with the applicable land and resource management plan and will not substantially interfere with the nature and purposes of the CDNST."

Nevertheless, some fear that decision could result in pressure being placed on National Park Service land managers to permit the bikes into wilderness areas as this development potentially opens one more door for mountain bikes to public lands that have long been set aside for hikers and horseback riders.

From the beginning, "one of the primary purposes for establishing the Continental Divide National Scenic Trail (was) to provide hiking and horseback access to those lands where man's impact on the environment has not been adverse to a substantial degree and where the environment remains relatively unaltered," the Forest Service notes in its Federal Register notice. "The basic goal of the trail is to provide the hiker and rider an entree to the diverse country along the Continental Divide in a manner, which will assure a high quality recreation experience while maintaining a constant respect for the natural environment. ... The Continental Divide Trail would be a simple facility for foot and horseback use in keeping with the National Scenic Trail concept as seen in the Appalachian and Pacific Crest Trails."

While the Forest Service notes that hiking and horseback use are the "primary purposes" for the trail's existence, they are not the trail's exclusive uses, said Janelle Smith, a spokeswoman for the agency's Rocky Mountain Region. Mountain biking could be permissible as long as it doesn't degrade the trail, she said.

“We just wanted to make sure that we’ve got a trail that is sustainable over time. The original intent of the trail was for hiking and horseback riding. That is designated by Congress," Ms. Smith said Monday from her Denver office. "So we needed to clarify that, and as these other uses are compatible with that, those initial uses, then it's really up to those local land managers to either designate a certain area of the trail that would only be for those uses of the trail or make some modification for those multiple uses

“Some trails lend themselves to being able to mountain bike on them," she said.

The Forest Service was lobbied somewhat heavily by mountain bikers to give them access to the trail. Back in 2007 the International Mountain Bicycling Association mounted a campaign among its membership to urge the Forest Service not to close off the trail to their use.

IMBA believes a shared-use philosophy that includes bicycling is compatible with the intent and purpose of the CDT, and that mountain bikers can help overcome these significant hurdles impeding the trail's completion. With 40 million participants, mountain biking is the second most popular trail activity in the country (Outdoor Industry Foundation, 2007). This large constituency helps lobby for public lands funding and donates nearly one million volunteer hours each year to trail construction and maintenance. Mountain bikers can be valuable partners for the CDT.

Among long-distance trails, the CDT is unique in that has generally allowed mountain biking. Unlike the Pacific Crest Trail or Appalachian Trail, mountain bikes are largely welcome on non-Wilderness sections of the CDT. IMBA isn't asking for access to all 3,100 miles, but there are many non-Wilderness sections where non-motorized users can get along and mountain biking should continue.

The group's call was heard. During the public comment period on the updated management plan, a bit more than 8,000 comments were received, according to the Federal Register note. Approximately 7,200 of those comments were received "principally (from) mountain biking enthusiasts, who submitted comments in the form of the same electronic mail," the agency said.

While National Park Service officials working on Yellowstone's winter-use plan, which has drawn hundreds of thousands of public comments, with a strong majority supporting the phase-out of snowmobiles, say public comment does not equate with a vote on the issue at hand, at the Forest Service Ms. Smith said the large number of comments backing mountain biking couldn't be overlooked.

“Certainly, any time we get that kind of response it helps inform our decision," she said. "When it comes to changing some direction that we provide to our land-management agencies, we wanted to make sure that mountain bikers, any user, has access to the public process when final decisions are made on granting access to any part of the Continental Divide Trail.”

Interestingly, a bike route already parallels the Continental Divide Trail.

"The Great Divide Mountain Bike Route is our premier off-pavement route, crisscrossing the Continental Divide north to south," say the folks at Adventure Cycling, a non-profit cycling association. "This route is defined by the word "remote." Its remoteness equates with spectacular terrain and scenery. The entire route is basically dirt-road and mountain-pass riding every day. In total, it has over 200,000 feet of elevation gain. All of this climbing gets the rider into visually spectacular places and incredibly fit shape."

While it remains to be seen which, if any, sections of the trail are opened to mountain bikes, officials in Glacier and Yellowstone are not concerned about riders venturing into their parks.

"We don't have much, if any, concern that visitors might try poaching rides on the CD trail in Glacier National Park," park spokeswoman Amy Vanderbilt said. "Glacier does allow the use of bikes in a few locations in the park (Apgar bike path between West Glacier and Apgar Village as well as all park roads). We even allow bikes on the Sun Road except for two sections west of Logan Pass from June 15 (when pass is accessible) to Labor Day, between 11 a.m. and 4 p.m. (due to heavy traffic and narrow, windy sections).

"Very infrequently, we do have visitors biking where they shouldn't, but our Visitor and Resource Protection staff out on the ground do a pretty good job of making sure that such illegal park use doesn't happen," she said.

While the American Hiking Society generally opposes bikes on hiking trails, officials there did not respond to a request for comment on the Forest Service's new stance on mountain bikes on the Continental Divide National Scenic Trail.