Cyclists are required to signal turns just as drivers are—or, rather, should. Specific turn laws vary by state, but the Uniform Vehicle Code (the UVC is a suggested set of traffic laws for states) provides a standard that helps us understand the basic requirement.
Under the UVC, cyclists must signal their intention to turn right or left continuously for the last 100 feet before the turn. If the cyclist is stopped and waiting to turn, the cyclist must signal while stopped, although that signal need not be continuous. As far as how you signal, the UVC used to require you to use the same hand signals drivers use: left arm extended for a left turn and, for a right turn, left arm extended with your forearm extended upward. But thanks to a newer, bike-friendly addition to the UVC, you now have the choice to signal a right turn with your right arm extended straight.
What about stops? Drivers signal stops with brake lights, but the UVC does not require cyclists to signal their intention to stop. Nevertheless, at least some states do require cyclists to signal stops. For example, in Oregon cyclists are required to signal continuously for 100 feet before stopping, with the left arm extended downward, as a driver would do if using hand signals. Check your state’s laws for specifics.
The obvious question about hand signals for cyclists is: What happens if you need to use your hands for braking or for maintaining control of your bike? After all, your most powerful brake is your front brake, and it is operated by your left hand—the one you are supposed to use to signal your intention to stop. If you follow the law literally, then you would never use your front brake or your left hand to help steer the bike in the 100 feet before a turn, because you would instead be signaling the turn.
Fortunately, according to the UVC, if your hand “is needed in the control or operation” of your bike, you are not legally required to signal. So, essentially, the law says you must signal only when it is safe to do so. For example, you might briefly signal your intention to turn or stop so that drivers behind you know that you will be turning or stopping, and then put your hand back on the bar so you can operate the brake lever or steer to avoid hazards. (If you want to signal turns or stops but also want to keep your hands on your bar at all times, you can buy taillight signals similar to those on cars from the American Bike Safety Company; safetybikesignals.com.) No matter how you choose to signal, the point of the law is to strike a commonsense balance between the competing safety concerns of letting others know what you are planning to do and maintaining control of your bike.
Research and drafting provided by Rick Bernardi, J.D.