Besides the thousands of miles, various obstacles stand in one's way when biking from the Pacific to Atlantic oceans in four weeks, as Dr. Fred Landenwitsch and his friend Joe Vonderheide did last month.

Headwinds, for example. Nothing like riding 10 hours straight into powerful headwinds, which can cut mileage by more than half with more exertion.

Or vehicles hugging highway shoulders. Is anything more intimidating than riding a bike with a speeding tractor-trailer truck at your elbow?

But worst of all -- angry canines. Who let the dogs out, when one's simply trying to pedal cross country?

"Dogs are the nemesis of bikers," said Dr. Landenwitsch, a 49-year-old South Strabane resident and partner at Claysville Family Practice. "We were chased 100 times by dogs."

To raise $70,000 to build a health facility in LaCroix, Haiti, Dr. Landenwitsch, a Cincinnati native, and Mr. Vonderheide of Lawrenceburg, Ind., started Jan. 26 in San Diego with back tires in the Pacific Ocean and traveled 3,150 miles in 28 raucous days, arriving Feb. 24 in St. Augustine, Fla., where they dipped their front tires into the Atlantic.

Pedaling 10 hours each day, they averaged more than 100 miles per day without taking any days off.

Their venture proved successful.

To date, they've raised $58,000 to build a medical center in LaCroix that will house a doctor and dentist all year round. For now, volunteer American doctors, including Dr. Landenwitsch, provide occasional healthcare for impoverished residents. The $70,000 would include enough to purchase a Jeep.

Donations still can be made at www.tourdesaints.org, or by sending a check to the TPC Haiti Mission Fund, c/o Claysville Family Practice, 1263 Route 40 West, Claysville, PA 15323.

The project Web site offers daily logs of their cross-country trek, a route map showing daily progress and photographs, among other information.

During the two-wheel journey, the two men overcame headwinds and avoided vehicles. But dogs ultimately did in one of them.

On the next to the last day, two rampaging dogs attacked Mr. Vonderheide on his bike, and sent him flying over his handlebars onto pavement. Dr. Landenwitsch patched him up with bandages and the trek continued.

The brutal schedule left little time for sightseeing. The two ate in restaurants and filled up on snacks at convenience stores to meet their daily requirement of 7,000 to 8,000 calories. Except for a few nights of camping, they stayed in motels.

"It was more work than fun," Dr. Landenwitsch said. "There was no free time. It was a hard day's work every day. The only TV channel we watched was the Weather Channel."

Stages through the Rocky Mountains were most difficult. Although they tried traveling back-country highways, they found themselves on a few busy roadways including a full day on dangerously twisting mountainous road with little room between heavy traffic and a guardrail separating them from a 100- to 200-foot drop.

"On the fourth or fifth day, I said to myself, 'This is a bad idea.' We were starting into the Rockies," Dr. Landenwitsch said. "It was important that we had a cause. If we hadn't had one, it would have been very easy to throw in the towel.

"We were held to the road by the cause."

Along the route, Dr. Landenwitsch had seven flat tires, but Mr. Vonderheide had only one. Their bikes held up well. And so did their bodies. Dr. Landenwitsch suffered sore knees, usually late each day at the 100-mile mark. He got plenty of sun and lost about 10 pounds.

Approaching the Atlantic Ocean proved emotional, Dr. Landenwitsch said. "A strange silence came over both of us. There was a feeling of accomplishment.

"To have ridden across the U.S. on an inch of rubber, to know you did it, is a very gratifying thing," he said, back in his office after a month away. "I'm amazed that a simple machine can carry a man and 40 pounds of luggage 3,000 miles with only a few flat tires."