Principles of Traffic Law

by League of American Bicyclists

Understanding the basic principles of traffic law will help you understand how to ride your bicycle in any traffic situation. All road users expect each other to act in accordance with these principles to avoid conflicts and collisions. Complying with traffic laws will decrease the likelihood of a crash by making your actions predictable, and make your ride more enjoyable. As a bicycle rider, in all states, you are accorded all the rights and assume all the duties of a vehicle driver. Therefore, drive your bicycle as you would any vehicle. Although a bicycle is very maneuverable, this does not mean that cyclists should violate traffic laws.

First Come, First Served

Operators of vehicles, including cyclists, are entitled to the lane width they need, with reasonable clearance behind and to each side, and reasonable stopping distance in front of them. Drivers must yield before moving into space occupied by vehicles that are there first.

Drive on the Right-Hand Side of the Road

Drivers of vehicles, including bicyclists, must drive on the right-hand side of the roadway. Traveling against traffic puts you in positions on the road where other drivers do not expect you, and makes it impossible for you to read signs and signals. To be predictable to motorists and other road users, never be a wrong-way rider. Many common crash types result from going against the flow.

Yielding to Crossing Traffic

Drivers on minor roads, including driveways and alleys, yield to traffic on more major roads. Yielding means proceeding onto a roadway only when it is safe to do so and obeying all traffic control devices (e. g. signs, signals and markings).

Yielding when Changing Lanes

Drivers who want to move into a new lane on the road must yield to traffic in their new lane of travel. Yielding means moving only after looking behind you to see that no traffic is coming and looking in front to see that the way ahead is clear. This is a special case of first come, first served.

Speed Positioning

In general, stopped or parked vehicles are next to the curb, slower moving vehicles are to the left of them, and faster moving vehicles are closest to the centerline. Overtaking on the right violates this principle and therefore is more risky that overtaking on the left.

Lane Position Rules

Ride three feet to the right of the motorized traffic when the lane is wide enough (about 14 feet) to share safely. When lanes are too narrow to share safely, control the lane by riding the center of the lane or just to the right of the center in the right hand tire track. This is legal in all states.

If traveling at the speed of traffic, a bicyclist should control the lane unless it is a very wide lane. If traveling faster than other traffic, overtake on the left, keeping a safe distance from slower traffic.

Intersection Positioning

At intersections, drivers position their vehicles so as to avoid conflicts with the movement of other drivers. Right turners are to the right of center, left turners are to the left of center and straight-through cyclists are between these positions.

Reprinted from League of American Bicyclists "Smart Cycling/Traffic Skills 101". For more information on good cycling tips, see How You Can Ride Better.
For more information about the League of American Bicyclists, visit their web site,, or e-mail them at

Serving the Pacific Northwest for over 12 years.

Home | Clubhouse | Sponsors | Links | Webmaster

©1998-2010 Seattle Bicycle Club, Inc.