It will come as little surprise to anyone who's seen the river of riders flowing along Market Street during commute hours that an annual census shows bicycling continues to boom in San Francisco.

The number of people riding bikes has increased 14 percent since 2011 and 96 percent since 2006. That's the conclusion of the 2013 bicycle count taken by the Municipal Transportation Agency in September and released Thursday.

"We are seeing more and more people riding a bicycle in San Francisco every day," Mayor Ed Lee said in a statement, "and the latest bicycle count data confirms what we are seeing on our streets."

The sharp increase in transportation by bike coincides with a surge in improvements - from parking "corrals" to bike lanes, sometimes with green pavement and protective barriers - around the city. It's all part of an effort to boost the percentage of trips taken by bike to reduce driving, pollution and crowding on Muni.

As part of the transportation agency's plan to get half of San Francisco's travelers to rely on something other than cars to get around, the city is counting on a continuing surge in cycling. A draft version of the bicycling strategy calls for increasing the 2012 estimate of bicycles accounting for 3.5 percent of all trips taken to a 2018 goal of 8 to 10 percent. A separate citywide survey is being conducted to calculate how people take trips around the city.

Commute-hour tally

The bike counts were taken on weekdays between Sept. 10 and 19 during the 4:30-to-6:30 p.m. peak of the evening commute. The MTA used volunteers and automated in-pavement meters to count bicyclists at 51 intersections around the city. Twenty-one of those intersections have been included since the counts began in 2006 and are used as the baseline for comparisons.

The highest counts came at intersections in the downtown core and the Mission District. Market and Valencia streets recorded the highest volume, at 1,365 daily bike trips during the evening commute, followed by Valencia and 17th streets with 1,337, and Fifth and Market streets with 1,267.

Streets experiencing the most growth in riders since the 2011 count were Townsend Street, which saw a 36 percent increase; Second Street, 35 percent; and Polk Street, 34 percent.

According to the report, bicyclists' travel patterns were similar to those of drivers and transit riders. Most people used busy streets or corridors such as Market Street; the Embarcadero; Fell Street; Oak Street; the Wiggle, a popular route between Market Street and Golden Gate Park; Alemany Boulevard; and Valencia Street; as well as Polk Street to travel to the city's northeastern quadrant.

Kristin Smith, a spokeswoman for the San Francisco Bicycle Coalition, pointed out that big increases in bike riding were seen in areas where bicycle improvements had been made. They ranged from markings that encourage drivers to share the road, to intersection and signal changes that accommodate cyclists, to new bike lanes, some physically separated from traffic.

Huge increase

At Portola Drive and O'Shaughnessy Boulevard, a new bike lane coincided with an 83 percent increase over 2011. At Page and Stanyan streets, bike-friendly traffic-signal changes were followed by a 78 percent rise. And 24 percent more bike riders passed through the intersection of 17th, Castro and Market streets after a new bike lane opened.

"Almost everywhere bike improvements were made, the counts went up," Smith said. "If you build it, people will ride there."

The coalition, which has become influential in San Francisco politics and transportation planning, advocates for a much more aggressive investment in bike improvements and notes that the city's gains have come despite what it considers minimal investment.

More bikeways

"The city spends just one-half of 1 percent of its transportation budget on bicycle facilities," Smith said. "We're excited to see what would happen if the city makes more substantial investments in more connected bikeways all across the city."

Whether that happens will be a big issue in 2014. Drivers, and sometimes merchants and residents, have objected to bike projects in their neighborhoods, especially those that take away parking or lanes of traffic. Yet city officials say they remain committed to boosting the number of bike riders.

"As bicycling becomes even more commonplace in our city," the mayor said in a statement, "we must meet and support the rising demand for better bikeways."