BELFAST, Maine — One year ago, ripples of shock and sadness spread out across Maine and beyond after David LeClair, a 23-year-old Trek Across Maine cyclist from Massachusetts, was killed in an accident just 10 miles after the start of the event.

On Thursday, LeClair’s co-workers at athenahealth will hold a private ceremony to remember the young man they described as having an unquenchable zest for life. On Friday morning, they’ll hop on their bicycles to join the American Lung Association’s 30th annual charity ride and support the cause he loved. So far, 225 people have signed up to ride with the athenahealth team — nearly double the number that rode with LeClair last year.

“People are really excited about being there together and being there for David,” Leslie Brunner, the athenahealth “chief people officer,” said Wednesday in a telephone interview from Watertown, Massachusetts. “It’ll be an emotional ride for us every year.”

All the riders will see some changes as they use muscles and willpower to pedal 180 miles from Sunday River in Newry to the Belfast waterfront over the course of three days, including biking the same stretch of roadway where LeClair was killed. An official from the American Lung Association said Wednesday that the Maine Department of Motor Vehicles has placed more signs on the roads to alert motorists about the event, and more police and emergency officials are planning to be out on the route of the trek.

“We do think that this year there will be an increase in visibility,” Michael Seilback, the vice president for public policy and communications at American Lung Association, said.

Another change is the new state law that went into effect in September that gives cyclists the right to determine for themselves the safest place to travel within a roadway. It is intended to add teeth to the state’s 3-foot rule, which stipulates that motorists must give at least 3 feet of clearance when passing bicyclists. Under the law, any accident involving a motor vehicle and a bicyclist is automatically considered evidence the driver violated the 3-foot rule.

Police said after the accident that LeClair grabbed his water bottle for a drink while cycling on Route 2 in Hanover when a tractor-trailer truck passed him. The big rig was 3 ½ feet to 4 feet from the cyclist when it passed, witnesses told police, but the draft caused LeClair to lose his balance and fall over. The cyclist hit his head and was partially run over by the truck, whose driver had not noticed anything unusual and did not stop until police pulled him over six miles down the road.

The driver, who was from Quebec City, was not charged.

Over the 30 years, the Trek Across Maine has grown from 106 riders to about 2,000 this year and last, Seilback said. It is the biggest American Lung Association fundraising event and has raised about $22 million over 29 years. Seilback said that the organization hopes this weekend’s event will bring around $2 million, which will help fund the organizations’ research, advocacy and education efforts.

“The money raised from this event is integral to the work we do,” he said.

James Tasse of the Bicycle Coalition of Maine said that his organization will coordinate a safety patrol during the event. He said patrollers will act as first responders and road ambassadors who will issue gentle reminders to participants about Trek conduct. The event is not a race, he said, and the patrollers will encourage riders to “calm down and enjoy the tour.”

Tasse said he had heard there may be more outreach to trucking companies about the Trek, including outreach to Canadian truckers at the border.

“My expectation is that this is going to feel like a pretty safe trek following last year’s tragedy. I think everyone’s going to be a little bit more on their guard. I hope that’s the reality,” he said. “In an event this size, there’s always some sort of minor mishap. People do crash and break collar bones. But there’s never been a fatality before. It’s a grim reminder that when bikes are on the road, [drivers of] motor vehicles need to be a little extra cautious when being near them.”