HATFIELD – This year, for the fourth time, a group – mostly men, mostly in their mid-30s to early-50s – will converge in town for a celebration of reclaimed youth and uncovered treasure, a celebration of BMX bikes.

The Hatfield BMX Show and Swap Meet, founded in 2013 by BMX enthusiast Steve Holloway, gives these people a chance to trade parts, win prizes and meet other hobbyists. On Aug. 20, the show returns for its fourth iteration, at the Lion’s Club Pavilion.

Holloway is 41, and he said collecting and restoring these bikes is particularly popular among men his age, especially those settling down with families. They need a hobby, and instead of playing golf, they restore bikes.

“It’s the same thing as baseball cards or stamps, but the good thing about bikes is you can take them out and ride them,” Holloway said.

People are attracted to the hobby for several reasons, he said. Some men – especially those in their 50s – grew up riding after the sport became popular in the 1970s. Most are enamored by the possible finds, the idea of discovering an exciting bike or part buried in the back of someone’s garage.

In the years since Holloway started the Hatfield event, he said, it’s attracted larger and larger crowds. He took a break from running the event last year, but a couple of his friends took over, and he said it brought in about 40 collectors and more than 200 bikes.

As one of the only such events in the area, he said, it’s also drawn people from farther reaches each year. People come from all over Massachusetts, as well as Delaware, New York, New Jersey and Rhode Island. Last year, one collector and his family drove in from Ohio.

“It’s kind of an ‘If you build it, they will come’ thing,” Holloway said.

He can also measure the event’s pull in weight – not of bikes, but of food. The show has no cost of admission, and the organizers only ask attendees to bring a nonperishable food item for donation to the Food Bank of Western Massachusetts. Last year the show raised 134 pounds of food.

“I try not to make money a focus of my life,” Holloway said. “I just want people to go there, have a good time and maybe help people out. I have friends who use the food bank, and that’s always in the back of my mind.”

The BMX show has some new features this year, like a competition category for kids up to age 13. Holloway has seen an uptick in the number of young people interested in building and collecting bikes, he said. Some of them are children of collectors, like his 10-year-old daughter, for whom he just built a first bike.

Most of the features are constants, like the swap meet, which Holloway said is perhaps the most exciting part of the day, as collectors find new parts and take on whole new projects.

“It’s an end of summer thing, and they can pick up their projects for the winter,” he said.

And then, next year, they’ll come back around.