Google on Monday launched its largest-ever collection of Street View images taken by a humble but versatile vehicle — the tricycle — as the Internet giant greatly expands the reach of the popular but controversial program beyond public streets into hiking trails, amusement parks, historical landmarks, parks and gardens.

Google’s Street View service has mostly been limited to places where cars mounted with cameras can drive. But now, Street View increasingly will include images of public and private sites ranging from selected hiking trails of the Rancho San Antonio Open Space Preserve near Los Altos to Sea World Orlando to Kew Gardens in London.

To extend Street View to places beyond the reach of its ubiquitous Toyota Prius fleet, Google is using ungainly, 250-pound, 9-foot-long, human-powered trikes with a 7-foot stalk of cameras on the back. The trikes were the brainchild of Google engineer Daniel Ratner, who visited cobblestone alleys impassible to cars in Barcelona, Spain, and realized Google needed something to record universities, parks, trails and other places, many of them private, where cars can’t go.

“I feel like we’re just scratching the surface of what sorts of images our users want to see,” said Ratner, as he showed off one of the trikes that he helped develop at Google’s headquarters in Mountain View. “We don’t compare the trikes to the cars. We see them as being complementary vehicles.”

Google now has Street View imagery for almost every major metro area in the U.S., as well as in 27 other countries. The program does not earn Google revenue directly, but the company considers it a valuable component of Google Maps, which does have a large and growing advertising element, said Deanna Yick, a Google spokeswoman.

Since it launched in 2007, Street View has also caused what may be Google’s biggest privacy problem, when its cars scooped up data from unsecured Wi-Fi networks in Europe and North America. Google said the breach was inadvertent and has pledged never to use any of the data it collected. One British village was so angry about Street View, viewing it as an invasion of privacy, that residents blocked Google cars from cruising their town.

But as he pedaled the Street View trike in places like Legoland and the Santa Monica Pier in Southern California, Ratner said, the reception was friendly. The Midpeninsula Regional Open Space District, which granted Google a permit to photograph trails in Rancho San Antonio and four other local preserves, hopes Street View will boost its visibility.

“It’s exciting. We’re trying to get the word out to the Bay Area and to the community about the open space preserves and the trails that are available to them,” said Leigh Ann Gessner, a spokeswoman for the district.

Google often hires soccer players and other athletes to pedal the heavy trikes, which have special gearing but are extremely heavy for a human-powered vehicle. The most common public reaction to the odd-looking trikes? “This is not tongue in cheek. They literally want to know whether we have ice cream,” Ratner said. A boxy unit on the back of the Street View trikes holds a generator and other electronic gear. But to a lot of people, it apparently looks like a freezer.

The trikes will increasingly allow Google to extend Street View beyond the public streets onto private property, if an owner requests being added to the partner program. Google lets private partners post Street View images on their websites at no cost.

After he returned from Barcelona in 2007, Ratner was visiting the Ferry Building in San Francisco with his wife when he noticed the pedicabs outside carrying up to four people. A senior mechanical engineer who normally works with Street View cars, he realized those trikes could be adapted for Street View. Ratner and a group of other engineers began to work on the trikes during their “20 percent time” — the aspect of Google’s culture that allows its workers to spend one-fifth of their time working on their own ideas.

Their first prototype had a single gear, and for the electronics “we just, like, duct-taped all this stuff on,” Ratner said. But by 2009, Ratner and his team were able to post the first non-car images on Street View. The number of available trike images greatly expanded Monday, as Google posted images from Europe, Asia and many U.S. sites, including the Bay Area parks.

“It’s been really exciting for me to see this thing go international, and have users have fun with it,” Ratner said.

Contact Mike Swift at 408-271-3648. Follow him at Twitter.com/swiftstories.