California's 3-foot rule for cars passing bikes to take effect

California's new "Three Feet for Safety Act" is about to take effect.

Who knows what will happen at flash point on the Bay Area's two-laners in the foothills, so popular with road bikers, fast cars and motorcycles.

The law Gov. Jerry Brown signed a year ago requires cars to keep at least 3 feet from cyclists when passing.

I've been on all the Bay Area's back-road two-laners, both with four wheels and two, and I cringe every time there's a showdown over space.

When the showdown is between two indignant principle-of-the-thing drivers, one in a car and the other on a bike, the close calls and collisions I've seen makes me lock my jaw and hold my breath.

One time I saw a car pass so close to a bike that its side-view mirror clipped the rider.

Another time I saw a group of cyclists ride four across to block a car, and after he blared his horn, give the driver the finger. The car driver then crossed over a double-yellow line to get astride of them and then slowly moved to the right to force them off the road or into single file.

So much time has passed since the law was signed a year ago, after five vetoes in previous years, that some drivers might have forgotten about it, especially a key component. It becomes law Sept. 16.

The version that will take effect does not allow drivers to cross a double-yellow line to pass. If they can't abide by the new 3-foot rule, they must slow to "a safe and reasonable speed" when passing. Vetoed versions of the bill allowed drivers to cross double-yellow lines to pass bikes at a safe difference.

California will be the 23rd state to enact the 3-foot rule. One Chronicle reader, Dave Meyers, tested the rule on the roads of Colorado.

"Colorado has had the law and when narrow road riding there last year, I was very impressed with how well the law was observed by motorists passing me," Meyers said.