Originally Posted by lynnef
When I took Traffic Skills 101 (League of American Bicyclists course), they recommended 3 seconds and BIG motions. None of this casual little signal thing
Absolutely; back upright, for right and left turns: arms up and away from the body, straight out on a line parallel to the ground if possible.
Riding a road bike, signaling with the left arm, have the bar-hand on the right brake hood, feathering the rear brake, being ready to drop the left hand down on the left brake hood in the event the need for a shorter stop arises. There is a certain skill developed from practice that's required for being able to safely and effectively brake a bike with one hand on the bar...certain types of bikes more than others.
It's not overly hard to do though, and most people should be able to manage. This is the encouragement I'd hope they get if they have doubts.