It sounds like a dream for cycling fans: For the first time, a leg of America's most prestigious bike race will snake all the way up Mount Diablo, headed to a grueling finish on its 3,849-foot summit.

But there are a few problems for those planning to watch the May 18 leg of the Amgen Tour of California on this scenic peak. How, exactly, will the many thousands of them get here? Where will they park? And, er, what happens when they need to go the bathroom?

Eager fans snapped up every available camping spot at Mt. Diablo State Park weeks ago, but already state park officials say they may need to cancel some of those reservations to keep private cars off the upper half of the 11-mile, dead-end road up the mountain, or to reallocate campsites to race workers.

From left, Adam Switters, of Citrus Heights, Nick Newcomb, of Santa Cruz, and Marcus Smith, of Berkeley, all members of the Northern California-based
From left, Adam Switters, of Citrus Heights, Nick Newcomb, of Santa Cruz, and Marcus Smith, of Berkeley, all members of the Northern California-based Mike's Bikes presented by Incase bicycle team, joke around as they easily crest the top of Mount Diablo during a training camp workout on Mount Diablo onFeb. 1, 2013. The last steep 200 yards of Mount Diablo's narrow Summit Road will be the finish line for Stage 7 of the Amgen Tour of California. The race, held on May 18, will start in Livermore. (Doug Duran/Staff)

Organizers have decided to bar fans on race day from driving farther uphill than the junction ranger station halfway up the mountain. That means the public will have to hike or pedal at least 4.6 miles uphill to see the finish amid a rugged park setting where water faucets and restrooms are few. And the trek could be much farther if lower parking spaces go as fast as expected.

"We know it's a challenge to stage a race to a mountaintop with one road leading in and one road leading out," said Dan Stefanisko, the chief ranger of Mt. Diablo State Park. "We know it will be a popular event, and we're working with the Amgen people to prepare. First and foremost, safety will be our top priority."

Space is limited

Many details are yet to be worked out between race organizers and government officials.

Access to the park will be a matter of big demand for limited space along narrow roads.

The park has a North Gate Road entrance from Walnut Creek and a South Gate Road entrance near Danville -- which merge into Summit Road leading to a parking lot with space for about 15 to 20 cars.

The summit and the last ultra-steep 250 yards leading to it will be in high demand among fans anxious to witness the end of an endurance duel featuring some of the world's top cyclists.

"Experienced cycling fans know that the best place to see a race is an uphill part," said Roland Gaebert, a former amateur racer and recently retired Mt. Diablo State Park superintendent. "The riders don't go by so fast. On the flat and downhill, they're gone in an instant."

But the limited space near the top also will be in demand by race organizers, members of the media and others.

Gaebert suggested fans should be prepared to ride or hike up the mountain early in the day, and carry water, food, sunscreen, umbrellas and seat cushions for the wait to see the race.

In Europe, fan preparations like these are common for Tour de France stages in the Alps and Pyrenees.

Park officials said their biggest concern is getting people safely down the mountain after the race, when drivers in cars and vans and people on bicycles and foot will converge on narrow roads.

Park officials estimated that 7,000 to 10,000 people came to or near Mt. Diablo State Park on a weekday last year to see Tour of California racers ride halfway up the mountain and then descend out of the park.

Bigger crowds are expected this year for the summit finish on a Saturday, when many people are off work.

'A challenge'

Eric Smith, the Tour of California course director, said races to summits have been staged safely and orderly.

"Diablo presents a challenge, but we have encountered similar situations and similar geologies for races," he said.

Other mountain races have attracted upward of 20,000 people willing to walk or pedal miles uphill to get to a good vantage point, Smith said.

The eight-day Tour of California begins in Escondido on May 12. A time trial will be in San Jose on May 17.

The Livermore start and Mount Diablo summit finish have been announced, but other course details have not.

The route is expected to go up South Gate Road as it did last year, but Smith said the full route will be not be announced until later this month.

Contact Denis Cuff at 925-943-8267. Follow him at Twitter.com/deniscuff.

Online extras
Watch a video of Mount Diablo from a cyclist's view at http://bit.ly/WSqSRA.
Check for race updates at www.amgentourofcalifornia.com or www.parks.ca.gov.