It’s a very simple proposition. People get together with their bicycles, musical instruments and other fun stuff. Some stationary bikes are connected to an electrical generator, and a handful of folks pedal away, thus producing enough juice to power amplification for bands to play.

No fossil fuel is expended, no pollution created, and a good time is had by all on a sunny day in a city park.

But that would be too simple, wouldn’t it? After all, the parks don’t belong to the people, but to the authorities who run them.

That’s pretty much what happened last Saturday, June 20, during much (but not all) of Bicycle Music Festival 3 in San Francisco.

“The Parks and Rec people and Park Rangers were waiting for us when we arrived Saturday at Marx Meadow (in Golden Gate Park) at 10 a.m.,” one of the festival organizers told me. “They knew our whole schedule from our publicity.

“For them there was only one issue: ‘Do you have a permit?’ We’d done the same thing the past two years, with no problems. This year was different though.”

Turned away from Marx Meadow, the revelers dispersed, only to clandestinely gather later at Lindley Meadow further into the park, between the Polo Field and JFK Drive. There the party rocked out for a while, as only five stationary bikers at a time translated pedal power into electric music for the body and soul.

Until the Golden Gate Grinchies showed up again and pulled, uh, stopped the unpermitted pedaling and partying once more.

Undeterred, the festival revelers took to the streets, where you don’t need a permit to pedal and party (yet), and became a moving musical feast from GG Park to Dolores Park.

There the authorities were awaiting them again, this time in the form of the SFPD. “We were way behind schedule,” the festival organizer informed me, “thanks to the park authorities, but the cops were nice enough to hang around until we showed up.

“It was the same story, ‘Gotta permit kid?’ Meanwhile, another group was setting up to show a movie in the park later. They did have a permit, so we asked them if we could use their permit until the movie started at 8.

“They said ok, and told the cops that, so we played until about 8. The cops stayed around in their cruisers to keep us company anyway.”

Finally the festival rolled and rocked on to Pier 7, the fishing pier just north of the Ferry Building downtown, where there were no authorities present to prevent pedal power from frolicking on into the night..