Miller tells his two children to drive gently and keep enough air in their tires -- he favors 35 pounds per square inch -- for the best fuel economy.

But he dodges the full brunt of record gas prices. He keeps his Subaru parked for days at a time.

Miller rides his bicycle to work, to the bank and to the store. Even on the worst winter days, he gets around on two wheels.

"It's for the exercise and also the cost of fuel, and just the wear and tear on the car," said Miller, 52. "And also your stress level. I think it's very nice to have a ride in the morning and in the afternoon."

His day starts early and, for most commuters, backward:

Ride to the office. Take a shower. See the sun rise.

He leaves his Durham home at 5:45 a.m. for the 9-mile, 30-minute commute to Research Triangle Park, where he is facilities manager for RTI International. With headlight in front and blinking red light behind, he pedals through side streets, along the American Tobacco Trail and down the bike lane on Cornwallis Road.

Lately, after the switch to daylight-saving time, Miller is on the job an hour before dawn glimmers through the hardwoods near his door.

"I've just always been a morning person," Miller said. "I like to get in early so I can get some things done. This place gets a little hectic, and all of a sudden it's 5 o'clock."

A big man with a low, unhurried voice, Miller appears unmarked by years and weather. His broad face is unlined, and his mustache a rich brown. He stands 6-foot-2 and carries about 225 pounds. If he doesn't ride his bicycle for a while, he says, he'll get up to 240.

Miller lived in North Raleigh when he started work at RTI in 2006 and then moved to Durham so he could commute by bike.

He has long experience on two wheels. Six years ago, he cycled 3,900 miles from coast to coast.

His last bike, with an aluminum frame, wore out after 25,000 miles on the road. The carbon frame of his new bike provides a springier cushion against the bumps. He replaces the rear tire every 1,500 miles or so, about three or four months of riding.

Trained as a mechanical engineer, Miller is overseeing construction of a 120,000-square-foot office building that will hold almost 500 workers at Research Triangle Institute. He met a few cycling colleagues last year when fellow RTI employee Pablo Torres organized a bike commuter challenge.

Miller won prizes for biking to work the most days in October (19) and logging the most miles (366). The new RTI Bike Commuters Group has about 30 members now. Miller is among the few who stay in the saddle through the winter.

"Jim is one of the most hard-core," said Torres, who is nursing a knee injury that has kept him off his bike this month.

Miller has more company on the road these days.

"I noticed quite a few cyclists the other day, in the warmer weather. I think we'll see a more active spring than last year, due to the gas prices," Miller said.

RTI is among a growing number of employers that offer bus passes, showers, bike lockers and other incentives for workers who do not bring their cars to work. Anyone stranded without a car can get an emergency ride home.

Miller appreciates the shower, but he hasn't asked for a ride home yet. He'll wait out a violent thunderstorm, or a downpour that would make it hard for drivers to see his bicycle.

But rain is a routine matter, and cold is measured in layers of clothing.

Seven layers is the worst. He wears thin gloves so he can handle the brakes and gears. His fingers get numb on the coldest mornings.

"When the nozzle on my water bottle freezes, I know it's below 25 degrees," Miller said one morning last week.

"I wore about four layers today. I would say it was in the upper 30s.

"Oh, it was very comfortable."