SAN FRANCISCO — Plans to put the brakes on bicyclists riding across the Golden Gate Bridge has cycling enthusiasts crying foul in this urban center of two-wheeled activism.

Thousands of commuters, residents and tourists ride the bridge’s stately span each day, and occasionally there is a smash-up when bikers collide with tourists drinking in the views or run into each other.

Still, the city was taken by surprise this week when bridge officials proposed speed limits as a way to lower the accident rate on San Francisco’s signature landmark.

The initial plan would hit riders with a $100 fine if they don’t slow to 5 mph around the bridge’s iron towers, or 10 mph along the bulk of the 4,200 span. There is currently no speed limit, and authorities say some riders have been clocked going over 20 mph.

But after groups of pedallers protested, the bridge’s board of directors decided to postpone a vote on the limits to allow public debate.

“Five miles per hour is definitely slower than I would ever go,” said Uri Friedman, a manager at Pedal Revolution, a non-profit bike shop near the hip cafes of San Francisco’s Mission District. “This just kind of penalizes someone who knows how to ride their bike. As it is already, having to navigate through the tourists as you’re trying to get out of town on a ride makes for a potentially frustrating experience.”

On Saturday, as busloads of tourists snapped photos using the stately span as a backdrop, Frances Denner was recovering from a near wreck on her rental bicycle. Pausing to admire the sailboats and surfers near the bridge’s base, she said she thought speed limits sounded wise.

“This person wearing full bike gear came around me and I wasn’t expecting it. It was a little scary,” said Denner, who was visiting from Wisconsin.

A committee of the Golden Gate Bridge, Highway and Transportation District first proposed the limits after commissioning consultants to do a cycling safety.

According to the Berkeley, Calif.-based firm Alta Planning + Design, there were 164 bicycle crashes from 2000-2009, and speed was cited as a factor in 39 percent of those accidents. Over that same time period, there were 235 reported vehicle incidents, including anything from a fender-bender to a more serious collision, said bridge district spokeswoman Mary Currie.

Cycling activists questioned how many crashes involved tourists on rental bikes, and said it was misguided to craft a safety policy to address speed, if that was not a problem in a majority of the accidents.

“There is poor visibility, and there are surfaces on the bridge that when the fogs rolls in can get really slippery or catch a cyclist’s tire,” said Kim Baenisch, executive director of the Marin County Bicycle Coalition, which opposes the limits. “To be ticketed for going 11 mph because you have some tailwind behind you seems really unreasonable.”

Completed in 1937, the Golden Gate Bridge is one of the world’s great engineering feats. Riding its narrow paths requires a keen sense of how to navigate the gusty winds, fog and storms that blow into the San Francisco Bay.

Scott Klimo, who bicycle commutes from his home in Marin County to San Francisco’s financial district, said he and his fellow commuters know how to ride at safe speeds because they do it every day. In his 10 years bicycle commuting, he has seen one accident, he added.

“It’s not that the tourists are bad people, but riding a bike safely isn’t their first priority. It’s enjoying the view,” he said. “A little bit better education or orientation from the bicycle rental companies would be a far more effective safety measure than imposing some sort of random speed limit on all of us.”

Bridge officials will have to balance a host of competing considerations as they consider future safety proposals. Space is one: this summer, bridge authorities plan to close the bridge’s west side, which serves as an afternoon bike lane, to complete a long-needed seismic retrofit. Tourism is another. In 2009, more than 15 million people visited the city, pumping nearly $8 billion into its economy, according to the city’s Convention and Visitors Bureau.

Bicycle ridership and the clout of local cycle advocacy organizations are also growing. According to the San Francisco transportation agency, ridership has increased by 58 percent since 2006.

The bridge and the adjacent coastal parklands also often play host to organized bicycle tours. And even the once-monthly Critical Mass bicycling movement sometimes rolls its way through Friday rush-hour traffic all the way to the bridge.

“Local riders and bicycle commuters need to recognize that part of their commute is an international tourist destination,” said Nina Barker, a visitor from Charlottesville, Va., who was preparing for her first bridge ride Saturday afternoon. “Why can’t they just make two lanes: one for commuters and one for all the people who come to visit this beautiful place?”