Five radlers the taste-testers liked: From left, South Street’s Lemon Shandy, Boulevard Ginger Lemon Radler, Stiegl Grapefruit Radler, Bitburger Lemon Radler and Great Divide Roadie Grapefruit Radler. (Goran Kosanovic/For The Washington Post)

The radler is designed for summertime imbibing: Half beer, half fruit soda and all refreshment, with a bright fruit taste and less alcohol.

The creation of the radler is usually ascribed to a Bavarian innkeeper in 1922, who found himself confronted by hordes of thirsty cyclists looking for some mid-ride refreshment. He mixed his dwindling supplies of lager with lemon soda, and a new drink called the “radlermass” was born. (“Radler” is German for “cyclist,” while “mass” is the Bavarian term for a liter of beer.)

The idea of cutting beer with nonalcoholic drinks predates the early 20th century: The English were mixing ale and ginger beer to make “Shandygaff” in the mid-19th century, though the term “shandy” has devolved to stand for any mix of beer and soda. And in 21st-century America, beer drinkers are rediscovering shandies and radlers, two terms often used interchangeably, thanks to craft breweries and European imports.

This year, Colorado’s Great Divide and Maryland’s Flying Dog released radlers as their summer seasonals, joining offerings from Boulevard, Victory, Narragansett and Leinenkugel, among others, and a growing number of canned German and Austrian radlers found on beer store shelves.

Aaron McGovern, the co-owner of D.C.’s Biergarten Haus, introduced Schöfferhofer Grapefruit, a 50-50 mix of hefeweizen and grapefruit soda, to the city’s largest German-style beer garden two weeks before the 2014 World Cup, and sales have never slowed down. “It takes over a pretty substantial portion of our sales in the summer,” he says. “We have 12 beers on tap, and it’s probably 15 percent of sales alone.” (Biergarten Haus also offers Bitburger’s Lemon Radler in 16-ounce cans, and it’s another top-seller.)

Sure, it’s easy to drink on a hot day, but McGovern thinks a secret to the style’s success is that both of the radlers sold at Biergarten Haus are just 2.5 percent alcohol by volume, less than half of the other beers on the menu. “Spend the afternoon in a beer garden, and it’s easy to go sideways after three or four hours,” he says. “It’s nearly impossible to do that with radlers.”

Bitburger, one of the biggest breweries in Germany, spent more than a year working on its radler recipe — a 50-50 split between Bitburger Pils, the top-selling draft beer in Germany, and lemonade — before it debuted in test markets in last fall. A full-scale American release followed this year, timed to warm weather. Tobias Lehmen, the American brand manager for Bitburger Braugruppe, says in an email that “it was always clear that the brewery would go with the traditional lemon radler to give our consumers the most authentic German experience,” instead of a grapefruit version like those from Stiegl and Schöfferhofer. “The grapefruit radler segment seems a little saturated at this point.”

That traditional formula is being followed at South Street Brewing in Charlottesville, albeit with a nod to American preferences. To create its Lemon Shandy, the brewery makes an ale with Cascade hops and California ale yeasts, and blends it with Maine Root Lemonade after fermentation. The 50-50 split knocks the alcohol by volume down from 8 percent to 5 percent, which is lower than most beers at South Street, but still double what you would find in a German version.

“Shandy is fun,” says owner Taylor Smack. “It’s not deep, it’s not complex; it’s just kick-back beer, and there is a time and place for every beer under the sun.”

Other brewers are taking it a step further and making their own sodas just to mix into their beer. Boulevard, which introduced Ginger Lemon Radler in 2014 and unveiled a Cranberry-Orange variant last fall, spent extensive time blending flavor combinations into the Kansas City brewery’s popular Unfiltered Wheat Beer, a process that ambassador brewer Jeremy Danner calls “sort of a controlled trial and error.” The result: A de-aerated ginger-lemon soda is blended into the beer between fermentation and packaging, creating a crisp and refreshing — there’s that word again — beverage that’s just 4.1 percent ABV.

“I think that beer fans have embraced [the style] because radler or shandy offers something quite different than any other style,” Danner says. “Sure, well-made Pilseners can be crazy delightful on a hot day, but it’s fun to drink beer that doesn’t necessarily taste like beer.”

The radlers from Boulevard and South Street are somewhat traditional in their composition, but the newest craft radlers actually veer away from a beer-and-soda mix. Flying Dog’s Summer Rental is brewed with grapefruit peel and natural pomegranate, period. “We do not do a beer/soda blend like a traditional German radler,” says senior director of communications Erin Weston. “It’s 100 percent beer, brewed to mimic that flavor profile.”

When Great Divide was developing Roadie Grapefruit Radler, which hit shelves in April, owner Brian Dunn says brewers experimented with a blend of beer and grapefruit soda. “We didn’t like the way it tasted,” he explains. “The problem with grapefruit soda is that the extracts they use tend not to have that pithiness,” a flavor that really comes through in the finish of Roadie. Instead, brewers hit on a recipe using “lots and lots” of grapefruit puree, which provides bright citrus aromas. “It’s something really different for us,” says Dunn, a fan of radlers who has been racing bicycles since college.

The question, then, is when a radler is no longer a radler. If you had handed me a glass of Roadie and told me it was Great Divide’s new grapefruit pale ale, I would have believed it. And that’s a pretty important difference. During a tasting of nine shandys and radlers at The Post, colleagues and I unanimously gave top ratings to Bitburger Lemon and to Stiegl Grapefruit, an Austrian radler that’s 40 percent lager, 60 percent grapefruit soda, and 2 percent ABV. Fizzy and effervescent as fountain drinks, their carbonation made them more refreshing, almost like a San Pellegrino soda, and underlined the bright fruit flavors.

The American craft beers, on the other hand, had noticeably less carbonation, like a “normal” beer, and their fruit flavors seemed soft and tentative, especially given the humidity the day we were tasting. Boulevard Ginger-Lemon and Great Divide’s “bitter grapefruit soda” did much better than Flying Dog or Victory’s light Cage Radler; the best we could say about Narragansett’s Del’s Shandy, which smelled vaguely of lemon Pledge, was that it would be easy to crush after a round of golf or mowing the lawn. In the middle of the pack: South Street’s Lemon Shandy, which lacked the oomph and verve of the Bitburger.

Ultimately, an old-school radler — an invigorating beer to consume after a bike ride — was what we really wanted, even though we were just sitting still.