When it comes to cycling events in national parks, how heavily should the National Park Service weigh whether an event is a professional race when deciding if it's a worthwhile event, and what other factors should it take into consideration?

That question arises in light of opposition to a professional bike race at Colorado National Monument but comparatively little concern over an 800-cyclist "recreational" ride at Mount Rainier National Monument.

No doubt, both have impacts.

At Colorado National Monument, concerns and opposition against allowing a stage of the Pro Cycling Challenge have hinged largely on the need to close the park loop road to general park visitors for a day to allow the stage to be run. That's a legitimate concern.

Yet while Thursday's 800-rider RAMROD -- Ride Around Mountain Rainier in One Day -- event doesn't require the park road to be closed to other members of the public, there will be inconveniences to other visitors in vehicles who might find themselves behind a slow-moving pack of cyclists, who perhaps can't find space in overlooks or pullouts due to dozens of cyclists taking a break, or who might find long lines at restrooms.

"I know it gets frustrating for drivers. That’s where some of the main impact is, is people trying to get places and having to go around bicyclists. But we do allow bicyclists in the park, and that’s something that people need to get used to anyway," said Mount Rainier Chief Ranger Chuck Young. “By the time they (RAMROD) get to the park, they’re spread out pretty good, so it’s not like one big mass of riders, 80-90 riders together, as you might have in a race. But yeah, anything anybody does in the park is going to have impacts. At least for the time-being we’ve decided that this ride is something that certainly has some impact, but I feel that it’s managed well enough that people can still enjoy the park."

In 2011, Park Service Director Jon Jarvis weighed in on the question of professional bike racing at Colorado National Monument, saying that “(C)losing the park to accommodate the needs of a commercial bike race goes against our Management Policies, would adversely impact park resources, and would deny access to the park to other visitors. Federal law and NPS policy restrict commercial activities in national parks to those that are ‘necessary and appropriate’ to park purposes. This bike race is neither necessary nor appropriate in the park."

But the Park Service might change its position on that. Not only has the agency said it would take a look at deciding which activities are appropriate for Colorado National Monument, but it has not publicly opposed next month's Tour of Utah, which will involve a maximum of 128 professional riders following state highways that traverse sections of Cedar Breaks National Monument and Bryce Canyon National Park.

According to Tour of Utah spokeswoman Jackie Tyson, roughly 100 support vehicles as well as two helicopters and some fixed-wing airplanes will be following the racers. The riders and their entourage will pass through Cedar Breaks and Bryce Canyon very quickly and require no road closures.

Meanwhile, the magnitude of the RAMROD event has park officials warning other visitors what to expect and what to watch out for, both for their safety and the safety of cyclists.

"Due to safety concerns and to minimize impact to other park visitors, the number of riders participating in this non-competitive recreational ride has been limited to 800 pre-registered riders—all rider slots have been assigned and registration for the 2013 RAMROD has been closed," Mount Rainier officials said in a release last week. "Motorists coming to the park that day should expect some traffic delays, congestion around designated checkpoints and support areas, long lines of bicyclists sharing the roadway and extra emphasis by law enforcement of speeding and other traffic violations that could pose a risk to riders."

Park officials also stressed that "(D)rivers and pedestrians are cautioned that bicyclists in large numbers will be sharing park roadways, including the road east from Nisqually Entrance, Stevens Canyon Road, State Route 123 and State Route 410 throughout the day."

Furthermore, "(S)low traffic along the riding route should be expected, as road shoulders are narrow or non-existent along many sections. Drivers may encounter bicyclists walking their bikes up the long grade or riding slowly to maintain control over sections of the roadway. Motorists are requested to use extra care when passing bicyclists, and to do so only when there is sufficient road clearance and an unimpeded line of sight to do so safely."

Deciding which events are appropriate for national parks understandably can be difficult for park officials, who often are trying to maintain good relationships with their local constituencies. RAMROD, for instance, has long been a popular bike ride around Mount Rainier. Sponsored by the Redmond, Washington, Cycling Club, the ride quickly fills its quota of cyclists.

Another popular park ride is the annual West Yellowstone to Old Faithful fall ride in Yellowstone National Park that attracts 350 riders and typically fills that quota in hours.

At the Coalition of National Park Service Retirees, spokeswoman Joan Anzelmo noted the difference between a professional bike race and a recreational ride when asked why that group wasn't questioning the propriety of the RAMROD event. However, she did add that Park Service officials need to be mindful that even "recreational" events don't get out of hand.

"Generally speaking, recreational special events operating under special use permits are not orchestrated for commercial profit; do not close park roads to the visiting public; event spectators are not stacked in large numbers roadside along the event route; and no low flying helicopters or fixed wing aircraft are required for event communications and news media coverage," Ms. Anzelmo said in an email. "These types of requirements which are necessary for modern-day professional sporting events and professional races to take place are deemed too impacting to fragile park resources and to the visiting public. CNPSR's position remains consistent with the National Park Service, professional races do not belong inside units of the National Park System.

"The Coalition of National Park Service Retirees does have a growing concern about the increasing numbers and broadening scale of special events being held inside national parks that have the potential to impact park resources and park visitors," she continued. "We urge our colleagues within the National Park Service to thoroughly evaluate all special event permit applications according to NPS policy and federal regulations. If permits are authorized for large recreational special events, we encourage the National Park Service to set specific parameters in the terms of the permit to best protect park resources and serve the visiting public as the primary objective and overriding responsibility of the agency."

At Public Employees For Environmental Responsibility, which not only questioned the proposed pro race at Colorado National Monument but also wondered why the Park Service hadn't required an environmental analysis of the Tour of Utah ride through Cedar Breaks and Bryce Canyon, Executive Director Jeff Ruch also noted that the RAMROD event didn't require any road closures.

However, he added that he didn't know enough about the event to say whether it nevertheless would have unacceptable impacts on the park's resources or other visitors.

"Our bottom line is that the NPS responsibly manage the assets within its care," Mr. Ruch said in an email. "With these other events, NPS is either MIA (missing in action) or delegating its responsibilities to focus groups."

At the National Parks Conservation Association, Rob Smith said a key difference between the RAMROD ride and the proposed race through Colorado National Monument is one of access.

"Basically no one (visiting Mount Rainier during the RAMROD affair) is denied access to anything. That’s different than closing the park for several hours," said Mr. Smith, NPCA's Northwest regional director. "You basically share the park, and you stay in the public areas. That's different than saying, 'Sorry, the park is closed for six hours, you can’t come through.'”

Cycling can be a great way to experience a national park. While professional racers arguably do little sightseeing as they pedal, the recreational cyclist can take her/his time, stopping at overlooks or visitor centers for information. But packs of hundreds of recreational cyclists streteched over 50 miles of park roads can have just as many, if not more, impacts on a park visit than a tightly bunched peleton of professionals.

Is an 800-rider tour "necessary and appropriate" to a park's purposes, or should recreational cyclists touring the parks be limited in size to a dozen or so? It's a question that deserves much discussion and consideration.