Here is the list of (May 2010) Seattle bicycle laws pertaining to bicycles and bicyclists in traffic.
Section 11.44.010 WHERE REGULATIONS APPLY. These regulations applicable to bicycles shall apply whenever a bicycle is operated upon any street, alley or way open to the public, subject to those exceptions stated herein.
Section 11.44.020 RIGHTS AND DUTIES OF RIDER. Every person operating a bicycle upon a roadway shall be granted all of the rights and shall be subject to all of the duties applicable to a driver of a vehicle, except as to the special regulation of this chapter and except as to those provisions of the Traffic Code which by their nature can have no application.
Section 11.58.050 OPENING AND CLOSING VEHICLE DOORS. No person shall enter, leave, or open the door of a motor vehicle on the side adjacent to moving traffic unless and until it is reasonably safe to do so, and can be done without interfering with the movement of other traffic, nor shall any person leave a door open on the side of a vehicle adjacent to moving traffic for a period of time longer than necessary to load or unload passengers.
Section 11.58.310 REGARD FOR PEDESTRIANS. Every operator of a vehicle shall exercise due care to avoid colliding with any pedestrian or person riding a bicycle upon any roadway and shall give warning by sounding the horn when necessary.
Section 11.52.020 GENERAL SPEED STATED. No person shall drive a vehicle on a street, alley or way open to the public at a speed greater than is reasonable and prudent under the conditions and having regard for the actual and potential hazards then existing. In every event speed shall be so controlled as may be necessary to avoid colliding with any person, vehicle or other conveyance on or entering the street, alley or way open to the public in compliance with legal requirements and the duty of all persons to use due care.
The driver of every vehicle shall, consistent with the requirements of this section, drive at an appropriate reduced speed when approaching and crossing an intersection or railway grade crossing, when approaching and going around a curve, when approaching a hill crest, when traveling upon any narrow or winding roadway, and when special hazard exists with respect to pedestrians or other traffic or by reason of weather or roadway conditions.
Section 11.53.190 DRIVING IN A BICYCLE LANE. The operator of a motor vehicle shall not drive in a bicycle lane except to execute a turning maneuver, yielding to all persons riding bicycles thereon.
Section 11.53.200 OVERTAKING A VEHICLE ON THE LEFT. The operator of a vehicle overtaking another vehicle proceeding in the same direction shall pass to the left of such overtaken vehicle at a safe distance and shall not again drive to the right side of the roadway until safely clear of the overtaken vehicle.
Section 11.44.040 RIDING ON ROADWAYS. Every person operating a bicycle upon a roadway at a speed slower than the normal and reasonable flow of motor vehicle traffic thereon shall ride as near to the right side of the right through lane as is safe, except as may be appropriate while preparing to make or while making turning movements, or while overtaking and passing another bicycle or vehicle proceeding in the same direction. A person operating a bicycle upon a roadway that carries traffic in one direction only and that has two or more marked traffic lanes may ride as near to the left side of the left through lane as is safe. A person operating a bicycle upon a roadway may utilize the shoulder of the roadway or any specifically designated bicycle lane if such exists.
Section 11.44.060 RIDING MORE THAN TWO ABREAST PROHIBITED. Persons operating bicycles upon a roadway or sidewalk shall not ride more than two abreast except on paths or parts of roadways set aside for the exclusive use of bicycles.
Section 11.44.140 HAND SIGNALS. All required hand signals shall be given in the following manner:
Left turn: left hand and arm extended horizontally beyond the side of the bicycle.
Right Turn: left hand and arm extended upward beyond the side of the bicycle, or right hand and arm extended horizontally to the right side of the bicycle.
Stop or decrease speed: Left hand and arm extended downward beyond the side of the bicycle.
Such hand signals shall be given continuously during the last one hundred feet traveled by the bicycle before initiation of a turn, unless during the last one hundred feet both hands are needed to control or operate the bicycle.
Section 11.44.240 CLINGING TO VEHICLES. No person operating any bicycle shall attach the same or himself to any vehicle.
Section 11.44.260 CONTROL. No person operating a bicycle shall carry any package, bundle or article which prevents him from keeping at least one hand upon the handlebars, nor shall he operate the bicycle at any time without keeping at least one hand upon the handlebars.
Section 11.44.160 LAMPS AND REFLECTORS ON BICYCLES. Every bicycle, when in use during the hours of darkness, shall be equipped with a lamp on the front, which shall emit a white light visible from a distance of at least five hundred feet to the front, and with a red reflector on the seat of a type approved by the State Commission on Equipment, which shall be visible at all distances up to six hundred feet to the rear when directly in front of lawful lower beams of head lamps on a motor vehicle. A lamp emitting a red light visible from a distance of five hundred feet to the rear may be used in addition to the red reflector.
Section 11.44.200 BRAKES. Every bicycle shall be equipped with a brake which will enable the operator to make the braked wheels skid on dry, level, clean pavement.
Section 11.44.210 MUST RIDE ON SEAT. A person operating a bicycle shall not ride other than upon or astride a permanent and regular seat attached thereto.
Section 11.44.220 PASSENGERS. No person shall use a bicycle to carry more persons at one time than the number for which it is designed and equipped, except that a person eighteen years of age or older may carry a child securely attached to his person.
Section 11.44.100 RIGHT-OF-WAY IN CROSSWALK. A person operating a bicycle across a roadway upon and along a crosswalk shall have all the rights and duties applicable to a pedestrian under the same circumstances, but shall yield to pedestrians upon and along a crosswalk. No person operating a bicycle shall suddenly enter a crosswalk into the path of a vehicle which is so close that the driver cannot yield safely.
Section 11.44.120 RIDING ON A SIDEWALK OR PUBLIC PATH. Every person operating a bicycle upon any sidewalk or public path shall operate the same in a careful and prudent manner and a rate of speed no greater than is reasonable and proper under the conditions existing at the point of operation, taking into account the amount and character of pedestrian traffic, grade and width of sidewalk or public path, and condition of surface, and shall obey all traffic control devices. Every person operating a bicycle upon a sidewalk or public path shall yield the right-of-way to any pedestrian thereon, and shall give an audible signal before overtaking and passing any pedestrian.
For more information about the Seattle Bicycle & Pedestrian Program, call (206) 684-7583.
Other helpful local bicycle information is on our bicycle resources page