Good times flow freely in Milwaukee. Millions of hangovers owe their existence to Brewtown, as do countless decibels of V-twin fun. It stands to reason that Harley-Davidson’s birthplace also has one of the oldest motorcycle police units in America.

The Milwaukee Police Motorcycle Unit formed in 1910, just seven years after H-D’s founding. Its first Harley had one cylinder, displaced 30ci, and had white rubber tires. They must have liked it. Today, 109 years later, nothing but Harleys have rumbled underneath motor-unit officers. What would it take to switch to another bike?

“An act of God,” officer Dave Lemanczyk says.

Someone floated the idea 20 years ago, albeit briefly. The motor unit tested a BMW, but when city hall found out, the idea was quickly quashed. The fate of the test bike is unknown.

Today the 55-bike fleet calls a facility on West Vliet Street home. It shares space with the SWAT unit. The building dates to the early 1900s and is the oldest functioning police building in Milwaukee. Prohibition-era arrestees were dropped off and processed here. Notable alumni? Try John Dillinger.

The Milwaukee Police Motorcycle Unit counts 44 officers in its ranks, including one current female officer. Some are second-generation. Officer John Kulmann’s father was a motor-unit officer in Milwaukee, while Sgt. Roberto Colon’s uncle was a motor-unit officer in Puerto Rico. Kulmann vividly remembers the sight of his dad’s bike in the garage.

“It was just something you were born and raised with,” he says.

Kulmann’s father backed up one of Colon’s first foot chases, and Colon still remembers the thundering Harley as it cornered the suspect in a south-side alley. He entered the motor-unit program shortly thereafter.

Remarkably, officers are responsible for all motorcycle maintenance, and some repairs are even done by officers, led by Lemanczyk. It’s partly for budget reasons. Less money spent on repairs means more money for safety gear. But it’s also the pride of ownership. Unlike picking a random Crown Vic from the station lot, each motorcycle belongs to an officer. Each is outfitted and optimized for an officer’s physique and taste. Do they lend their bikes out to other officers?

“We don’t like to do that,” Lemanczyk says.

Salt is a big problem. The bikes get routinely washed in the heated garage. Motor-unit bikes live on city streets, not highways, so wheel bearings are frequent victims of potholes and winter-scarred pavement. Not fork seals, though. The Harley units are good for about six years. Bikes are typically kept in service for about three to five years before being traded in for newer models. The 2012 models make up most of the fleet, but are due for replacement this year.

“Three or four years is the magic number. After that, they start eating through the budget,” Lemanczyk says.

Officers wire the bikes for police radios, sirens, and auxiliary power for laptops. They regularly devise their own systems for luggage hardware. Gear designers learn from the motor unit. The laptops in the trunk are attached with a “Milwaukee mount.” Other gear is timeless, with some sirens dating back to the 1950s.

“If they’re still good, we keep using them,” Lemanczyk says.

Winter duties are light for the motor unit, with officers reverting to cars, or “cages,” for duty. But even in winter, traffic detail for bigger events such as Bucks games put bikes on the road. Some enjoy time out of the saddle, but for others the itch to ride won’t wait till spring.

“In February I start getting requests to take bikes out on a daily basis,” Colon says. Californians, take note.

The garage is surgically clean, with a lone SWAT vehicle keeping the bikes company. A tiny office on the southwest corner of the building is where suspects were once unloaded from police vans. Now it’s an unofficial lounge. Government-issue furniture sits next to officers’ snapshots, souvenirs, and a framed photo of a 1968 riot arrest. These walls have absorbed thousands of stories from opposite sides of the law.

Milwaukee has more than its fair share of crime and challenges. But motor-unit officers see themselves as more than just cops. They also provide community outreach.

“You’re much more approachable,” Lemanczyk says. “You’ll be at a red light, and someone will roll their windows down and joke, ‘Hey, wanna trade?’ ”

Asked if the unit had a message for trouble-minded visitors, he simply smiles and says, “Go back to Chicago.”