If you feel unsafe riding a bicycle on a San Francisco street, there's a good reason.
It's not safe -- and it's for expert riders only.
Only about 10 percent of San Francisco's bicycle routes are safe for riders of all ages and abilities, according to the San Francisco Examiner.
Routes are rated on a scale of 1 to 4, with 4 being the hardest, "experts-only" routes, the newspaper reported. That means only "strong and fearless riders" should attempt to pedal on places like Market Street.
It would take about $600 million to make all the routes safe for all riders, the newspaper reported. About $30 million is available.
Riders from "8 to 80" can ride safely in Golden Gate Park and the Presidio, according to the Examiner.