On his railcycle, Dr. Richard Smart, a 37-year-old dentist who lives in Coeur d'Alene, Idaho, is riding out of the 19th century.

The modified two-wheeler was called a railroad velocipede when it was invented in the early days of steam to inspect the tracks or go for help when a train broke down. Smart's modern version improves on the original: It converts into a regular bicycle off the tracks, adjusts to various widths of rail and can be ridden through switches. A net attached to the outrigger bar allows the cyclist to carry up to 40 pounds of, say, camping equipment. Onrushing trains are no problem since the 75-pound vehicle can be lifted off the track in a few seconds. In six years of railcycling Smart has never had a close call, partly because he stays off heavily traveled routes. "I feel safer on the tracks than riding my bike on the street," he says.

Inspired by an old photograph (left), Smart set out to design his own version of the velocipede in 1975. After six months of tinkering in his garage workshop, he was ready to test it. The standard bicycle wheels ride on top of the track. Attached just ahead of the front wheel are four guides that straddle the track and keep the bicycle upright. A set of metal bars on the side of the bike folds out and extends a small wheel to the opposite rail. Smart patented his railcycle in 1980.

Today he has five railcycles in working order. They have only one drawback: Every time he takes to the rails, Smart is technically trespassing on private property. Undaunted, he is trying to sell his railcycles (for $600 to $800) to owners of small railroads who could rent them to tourists for use on their lines. Until then the North Carolinaborn father of four will continue to hop aboard his railcycle after work and on weekends. In 1979 he even rode it on an 11-day vacation through the Canadian wilderness.

"The United States has thousands of miles of abandoned railroad tracks," Smart notes. "A whole system of bike paths is out there ready and waiting."