State has a Far Right as Practicable Requirement

Washington requires a bicyclist moving slower than traffic to ride as near the right side of the right through lane as is safe, with exceptions for turning, avoiding hazards, and overtaking.

Allows Two Abreast Riding

Two-abreast riding is allowed; riding more than two abreast is prohibited except on bicycle-exclusive paths or roadway sections.

Single File is Required

Washington does not require cyclists to form a single file line; riding two abreast is allowed, subject to the general duty to ride far enough right to let a faster vehicle pass on a shareable lane.

Has a Safe Passing Law

Motorists must move fully into another lane to pass a bicyclist where the road has multiple lanes; on a single-lane road, they must reduce speed and pass at a safe distance of at least three feet where practicable, or move completely into the oncoming lane if that distance isn't available.

Helmets are required on the road

Washington has no statewide law requiring a bicycle helmet for riders of any age. Helmet requirements, where they exist, have historically been set by local ordinance (for example, several King County jurisdictions), not by state law.

If Bike Lanes are present, they are required ( except when unsafe )

A cyclist may use a bike lane or shoulder where one exists, but Washington law does not require it — the cyclist may instead use the general travel lane subject to the roadway-positioning rules.

Riders may use the sidewalks

Allowed statewide; a cyclist riding on a sidewalk or in a crosswalk has the same rights and duties as a pedestrian. Local jurisdictions may further regulate or restrict sidewalk riding.

Does the Impeding Statute Apply to Bikes

Washington's bicycle-specific statute requires a cyclist in a single travel lane wide enough to share with a car to position far enough right to let faster traffic overtake, unless it's unsafe or the cyclist is turning — a narrower duty than a general motor-vehicle impeding law.

Whether cyclists may treat stop signs as yield signs (the "Idaho stop").

Washington's "Safety Stop" law lets a cyclist treat a stop sign as a yield sign: the cyclist may slow down and proceed without a full stop if it's safe, yielding to any traffic or pedestrians with the right of way, and stopping only if safety requires it. It does not apply at an active railroad grade crossing or where a school bus stop signal is displayed, and it does not extend to red traffic lights.

Restrictions exist on e-bikes and usage

Washington classifies electric-assisted bicycles into three classes and restricts where each class may operate: class 3 e-bikes are generally barred from sidewalks and shared-use paths (absent local authorization), while class 1 and 2 e-bikes may use shared-use paths and bike facilities, subject to further local restriction.

Allows the concept of Contributory Negligence that allows any contributory fault resuls in 'no fault'

Washington uses pure comparative fault: an injured cyclist's damages are reduced by their own percentage of fault, but no amount of fault — even a majority share — completely bars recovery.