I'm new to riding a Tandem. When riding in a group on a single bike people use hand signals when slowing or there is something in the road. Also we will say car back if there is a car back, etc. What are the different verbal or hand signals between the captain and stoker. For example if you are going to shift up or down what do you say to the stoker. If you are going to turn left or right do you say anything? How about when you start braking?