Wayne Ross was bicycling from one end of the Earth to the other to fight multiple sclerosis when he crashed. Now, it is he who faces a lifetime in a wheelchair.

Ross broke his neck last week when he crashed into the back of a bus in Guatemala. He is now in a Boston hospital, paralyzed from the chest down and needing all his strength just to press a button on his television remote control."I was riding to raise money for people in wheelchairs," Ross said Sunday night. "It's kind of ironic that I end up in a wheelchair."

A former Air Force officer, Ross has run, walked and ridden for numerous charities since leaving the service for a teaching career. After breaking his neck, Ross, 30, will probably never walk again, doctors said.

On June 12, Ross and Christopher "Spike" Ramsden, 31, both of Scituate, set off from Prudhoe Bay, Alaska, on a 16,000-mile bicycle trek to benefit the Multiple Sclerosis Foundation. They also wanted to make the record books.

Covering about 70 miles a day, they hoped to arrive at the tip of South America, Cape Horn, by St. Patrick's Day and set a world record for the longest continuous bicycle ride.

The men became celebrities in the countries they rode through, even dining with Guatemalan President Alvaro Arzu on Tuesday night. The following day, Ross was pedaling on the crowded streets of Guatemala City when the bus in front of him stopped abruptly.

Ross smashed head-on into the back of the bus, fracturing three of his vertebrae.

"I threw my hands up over my head," he said. "But it was too late. I speared the back of the bus with my head. I rebounded and hit the pavement, and I knew right away my neck was broken, because my head was twisted around in a strange way."

Guatemalan doctors operated on his neck and he was flown Saturday to Boston University Hospital to begin three months of rehabilitation.