When the ride begins, so does the fun.

Two nights a week, bicyclists gather at Pat’s Bike Shop on Wilson Street in Brewer, form a loosely aligned convoy, and head out on a long ride — somewhere, anywhere, as long as it’s a long ride. Leaderless by design, the nameless cycling group may travel up to 40 miles before returning to Brewer by dark.

David Rudnicki of Bangor has ridden with the group since the 1990s. He enjoys “just being with the people. They’re a great group of guys.”

“I like to get out and ride,” says Scott Seymour, who owns Pat’s Bike Shop.

The bike shop’s founder, Pat Pelletier, initiated the rides in the 1970s, according to Seymour, who joined the rides after Pelletier hired him in 1986. Seymour purchased the Brewer shop in 1997.

The rides take place Mondays and Wednesdays, starting with the “spring-ahead” time change and ending as the retreating sun eliminates sufficient late-day riding time in mid-September. Some riders are out year-round, albeit after trading the narrow tires of summer for the wide tires of winter as snow covers the roads and trails.

Seymour never knows who will show up for a particular ride. Many cyclists are “regulars” who ride at every opportunity; one evening a Minnesota cyclist vacationing at Branch Lake in Ellsworth joined the group for a fast-paced tour of the lower Penobscot Valley.

Demographically, these road warriors tend toward the not-so-young at heart. Ages range through the 30s, 40s, and 50s; “we have several that are 55, 60, 65,” Seymour says, mentioning one cyclist in his mid-60s who averages several thousand miles a year.

Except for the semiweekly rides originating at Pat’s Bike Shop, most cyclists have little or no other social contact. “Some of the guys will ride in smaller groups,” Seymour says. He mentions “one small group” that occasionally takes nighttime “century rides” somewhere in Maine; clad in reflective clothing and pedaling bikes equipped with head- and taillights, these cyclists ride throughout the night and often conclude the event with breakfast somewhere in the Bangor area.

By 5:45 p.m. on this particular Monday, appropriately attired bicyclists are already spinning their wheels in the parking lot. Rudnicki, who was “ready to ride” when he arrived a few minutes earlier, swaps stories with another bicyclist:

• Rudnicki describes how a motorist nailed him on Hammond Street a while back.

• The other rider sports elbow-and-knee bandages; within the last 48 hours he has taken a bad spill on a gravel road near Phillips Lake in Dedham.

These die-hard bicyclists ride when hurt, scarred, and bleeding. Tonight they’re simply going to ride.

Rudnicki has already ridden today. Employed as a mechanic at Greenway Equipment Sales on Outer Hammond Street in Bangor, he rides his Specialized S Works M4 “to work every day I can.

“I don’t have to pay that $3.50 [per gallon] for gas,” he says.

Before each ride, attorney Arthur Greif usually suggests a destination and the routes “there and back,” Rudnicki says. Tonight the target is Kenduskeag; as soon as Seymour turns off the shop lights and locks the front door, the cyclists will zoom northwest on Wilson Street, cross the Chamberlain Bridge, and hook a right onto High Street.

Observing the traffic laws, they will pedal a good 40 miles through Brewer, Bangor, Levant, Kenduskeag, Glenburn, and Hermon before crossing the Queen City boundary on the inbound leg.

The cycling group varies its route and intensity with the particular weekday. The typical Monday evening ride “is what we call ‘moderate,’” Seymour explains. “We try to keep it at 18 miles per hour [in average speed], go maybe 30 to 40 miles.”

He describes the typical Wednesday ride as “faster, more aggressive in speed and distance,” with riders averaging 22-23 miles per hour and pedaling 30-40 miles.

The longest evening ride ever undertaken from Pat’s Bike Shop occurred near the summer solstice and covered 50 miles from Brewer through Orrington and Bucksport to Verona Island and across the Penobscot River. Then the bicyclists turned right onto Route 174 and rode past Fort Knox while en route to Route 1A in Prospect and then north to Bangor.

Even on a 30-to-40-mile ride, “you’ve got to hope for no flat tires or chain complications,” Seymour says. Besides inattentive drivers, slotted catch basins, and the occasional loose dog, road hazards abound; “glass or little shards of metal, debris in the road can cause flats,” he says.

“There’s a lot of stuff on the roads around here,” he says.

Although riders should return with at least a bit of twilight left, “we’ve been out in the dark before,” Seymour admits. During one epic mid-September ride, the cyclists pedaled up Center Drive in Orrington and headed toward Route 46 in Bucksport via the East Bucksport Road.

About the time they reached Dedham Village on Route 46, “we stopped to wait for one of the guys to catch up,” Seymour remembers. Some time passed; eventually a Dedham-bound motorist stopped to report a bicyclist struggling with a flat tire well south on Route 46.

So his companions backtracked to find the cyclist near the Church Road intersection, Seymour recalls. With darkness descending, “the shortest route [home] was back the way we’d come” through Orrington, he says.

The Monday and Wednesday rides are open to other cyclists; simply “be here ready to ride at 6 [p.m.],” Seymour says.

He means it; every Monday and Wednesday, Seymour promptly turns out the store’s lights and locks the front door at 6 p.m., hops onto his bike seat, and joins the fun.

And he stresses that the Pat’s Bike Shop rides are “by no means” the only such rides in Maine. “Most [bike] shops throughout the state offer a group ride of some sort,” Seymour says.

For more information about such rides, log onto http://www.bikemaine.org/events/weekly-rides-in-maine.