ASPEN (AP) – For aging or injured cyclists with diminished ability to get up and go, e-bikes beckon as a way to keep them in the outdoor pursuit they love, but for some public land managers the pedal-assist bikes are a looming headache.

E-bike use has exploded over the past year. Once spurned by cyclists, they are now getting more respect in a cycling industry always on the prowl for the next niche segment.

Aspen Velo bike shop invested in 20 to 25 e-bikes for its rental fleet and has about that many for sale, said Luke Wampler, who runs the shop with his father and store owner Michael Wampler. They started renting e-bikes last season, which were slow to catch on.

“Then in August, we couldn’t keep them in the shop,” he said.

The trend continues this year. On a recent Friday, Aspen Velo rented out about a dozen of the pedal-assist bikes.

E-bikes have a small rechargeable battery that provides assistance while the craft are being pedaled. They typically have four settings, the most powerful of which provides enough juice to travel as fast as 20 mph.

Wampler said they’ve been popular with older clientele.

“Eighty percent of our customer base is gray-haired,” he said.

Customers typically rent them for the climbs up to Pine Creek Cookhouse on Castle Creek Road, Maroon Lake and to the Woody Creek Tavern. Renters are told that e-bikes are prohibited on the paved Rio Grande Trail, Wampler said, “but we can’t stop them if they want to ride it.”

Pitkin County Open Space and Trails director Gary Tennenbaum said the program’s rangers are receiving an increased number of reports of scofflaws on the trail.

“It’s very easy to see – they’re going faster uphill than most people,” Tennenbaum said. “It’s becoming more of an issue.”

As it stands, public-land managers in the Roaring Fork Valley regard e-bikes as motorized vehicles. They are banned on routes where motorized uses are prohibited. Glenwood Springs is easing its ban on city trails during the Grand Avenue Bridge closure that starts Aug. 14. The Roaring Fork Transportation Authority board of directors will consider in August a request by the Colorado Department of Transportation to open the Rio Grande Trail between Glenwood Springs and Carbondale during the 95 days the new bridge is under construction this fall.

Tennenbaum said RFTA and Pitkin County are scheduled to examine their long-term policies prior to next summer to make sure they are on the same page. They share oversight of the Rio Grande Trail, with RFTA responsible for the stretch between Glenwood and Emma.

Pitkin County commissioner and RFTA board Chairman George Newman were emphatic at a July RFTA meeting that e-bikes have no place on the Rio Grande Trail because of the potential danger they pose to others on the popular and sometimes crowded trail. He contended it would be irresponsible to add to the mix pedal-assist bikes capable of higher speeds.

The Roaring Fork Mountain Bike Association isn’t advocating for greater access for pedal-assist bicycles, but Executive Director Mike Pritchard said they have their place.

“It’s relatively simple for us,” Pritchard said. “The public land managers have made their positions clear on this.”

E-mountain bikes are allowed on backcountry roads and routes that are open to motorized vehicles, he noted. They can be used on routes such as Lincoln Creek Road and the various roads up Aspen Mountain. He thinks e-mountain bikes would be especially appropriate on routes such as Summer Road up Aspen Mountain’s front side.

“You can really go up these roads that normally you wouldn’t ride because they’re so steep,” Pritchard said.

While the paved Rio Grande Trail is where most illegal use is occurring, there have been a few reports of e-bike use on the Smuggler Mountain-Hunter Creek Valley trail network and in Sky Mountain Park, Tennenbaum said.

He said they clearly pose a safety issue on a trail such as Airline and others in Sky Mountain Park, where two-way travel is allowed everywhere but on Deadline. There are steep pitches that lend themselves to high-speed descents on Airline and other trails. Sight lines are often limited. Uphill traffic has the right of way though some riders are either ignorant or belligerent about the rule.

Tennenbaum and Pritchard agreed it would be unwise to add pedal-assisted mountain bikers capable of maintaining a faster uphill speed to the mix. The higher speeds of e-bikes on uphill stretches combined with high-speed descents could be a recipe for disaster.

“Normally on a trail that you might be able to go 10 miles per hour on, you can go twice as fast,” Pritchard said.

However, he sees enforcement as a challenge because e-bikes will get harder to detect with advances in technology.

Shelly Grail, recreation staff manager in the Aspen-Sopris Ranger District, said e-bikes haven’t created an issue in the national forest surrounding Aspen. The U.S. Forest Service considers all e-bikes as motorized vehicles. They are welcomed on trails open to motorized uses, but prohibited on dedicated mountain-bike trails.

The Bureau of Land Management often accommodates mountain bikes and motorcycles on the same trails. Many routes in the Crown, the popular mountain in the midvalley, are open to both uses.

A lot of mountain bike purists criticize use of e-bikes to climb a trail. Pritchard said when cyclists are huffing and puffing their way up a climb, it strikes some of them as cheating when they encounter an e-biker covering the same ground quicker and easier.

“There’s just something weird that goes on in your brain,” he said.

Wampler said it’s harder to justify their use on dirt trails.

Tennenbaum said the public will get ample opportunity this winter to weigh in on the open space and trail program’s policy. Meanwhile, his staff is urging the bike-rental shops to educate their customers about closures. Rangers will keep their eyes peeled on the lunchtime crowds on the Rio Grande Trail.

“What the rangers have been doing is turning them around,” Tennenbaum said. “We haven’t been ticketing yet.”

He said he is unaware of anyone on an e-bike purposely outrunning a ranger to avoid a scolding. Rangers continue to rely on pedal power, unassisted.