Cycling Rule #34: A left turn is signaled by pointing your left arm to the left. A right turn is signaled by pointing your right arm to the right (what a concept). Using your left arm, elbow-out and pointed upwards was developed for motor vehicles prior to the invention of the electric turn signal since it was rather difficult for the driver to signal a right turn by reaching all the way out the passenger window from the driver-side of the vehicle. Alas, traditions (and habits) die hard. Using the left arm confuses motorists (except those born before the 1920s).