Hand signals

Hand signals are given by cyclists and some motorists to indicate their intentions to other traffic. Under the terms of the Vienna Convention on Traffic, bicycles are considered to be vehicles and cyclists are considered to be drivers. The traffic codes of most countries reflect this.

In some countries (such as in the Czech Republic, Canada, and the United States), hand signals are designated not only for cyclists, but for every vehicle that does not have signal lights or has damaged signal lights. For example, drivers of older cars and mopeds may be required to make hand signals.

Similar to automobile signaling, there are three primary signals: Left turn/overtaking, Right turn, and Stopping/braking.

US and Canada, (optional): Current convention for signaling right, either while cycling in traffic or cycling with other riders, is to extend the right arm perpendicularly to the body; to wit, the cyclist arm is pointing in the same direction of the intended turn. Prior to the common sense approach of extending right arm to indicate a right turn, the convention was for cyclist to extend the left upper-arm out to the left, horizontally and angle one's forearm vertically upward; this practice is no longer in use due to safety concerns. The Uniform Vehicle Code in the US recognizes both signals; although, the Code strongly encourages cyclists to use the arm to the right technique. State traffic laws generally conform to the Uniform Vehicle Code, but exceptions may exist. British Columbia (Canada) recognizes both.

Arm to the right has the advantage that it is more visible to any traffic likely to be affected, for example vehicles in the next lane to the right or also intending to turn right. It is also easier to teach to children: "point in the direction you are going to turn."

A bicycle's front brake lever is typically installed on the side of the handlebar closest to the center of the road (front-left for right-side driving). In many countries, the hand signal for stopping/braking requires that the cyclist signal with the hand used for the front brake. The front brake is the most effective method of stopping a bike under normal road conditions.

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Wikipedia