how it's supposed to be done

How is a car supposed to make a right turn from a street with a bike lane? It's one of the most widely misunderstood traffic rules (at least in California). Most cyclists, motorists, even cops don't get it, and the DMV doesn't express the concept as clearly as they should.

A right-turning car is supposed to move into the bike lane before the intersection, anywhere from 200 to 50 feet before, first signalling the lane merge, then merging right to the curb lane, then finally making the actual turn when safe.

The guiding principle is to always make a right turn from the right lane, and a left turn from the left lane, or left turn pocket if there is one. Turning across lanes is a big no-no, since it can (and often does) result in crashes and near-crashes, especially "right hook" collisions frequently suffered by bicyclists.

It's similarly dangerous for cyclists to make left turns from a right lane, and it's the same process in reverse to do it correctly: signal a left merge, merge left when safe (yielding to any traffic already in that left lane), signal a left turn, make the turn when safe.

A bike lane is a travel lane, like a standard travel lane, it's just not meant to have motor vehicles "traveling" in it. But to make a right turn, any vehicle (bike, car, truck, etc) is supposed to be in the right lane, so a motor vehicle needs to safely merge into the bike lane (yielding to any traffic already in that bike lane), before making the turn.

In San Francisco, streets with bike lanes usually have the left sideline of the bike lane dashed and sometimes dropped altogether the last 50-100 feet or so before an intersection, but hardly anyone ever explains how it's supposed to work, or why it's supposed to work that way (actually if you go to our Bike Ed classes you'll learn this along with a lot of other useful things).

Here are the pertinent parts of the California Vehicle Code (CVC):

Motor Vehicles in Bicycle Lanes

21209. (a) No person shall drive a motor vehicle in a bicycle lane established on a roadway pursuant to Section 21207 except as follows:

(1) To park where parking is permitted.

(2) To enter or leave the roadway.

(3) To prepare for a turn within a distance of 200 feet from the intersection.

{there's more about motorized bicycles in bicycle lanes, not prohibited so long as they're operated reasonably and prudently]

Turning Across Bicycle Lanes

21717. Whenever it is necessary for the driver of a motor vehicle to cross a bicycle lane that is adjacent to his lane of travel to make a turn, the driver shall drive the motor vehicle into the bicycle lane prior to making the turn and shall make the turn pursuant to Section 22100 [general turning regulations].

San Francisco Traffic Code addresses CVC 21209 (a) (1), that bit about being legal to park in a bike lane, by prohibiting it in almost all cases (SEC. 38.N).