Doubt the cagers will see a turn signal on a bicycle. I would go with the standard hand signals. I run my brakes motorcycle fashion with front on left. This allows me to use my left hand for signals. The front brake will do about 70% of the work in stopping a bike. Same as a motorcycle. The weight transfer to the front wheel during a stop creates more friction and shorter stops. MTB brakes will allow you to do stoppies easily.