other things you can do include using your head to indicate your intentions. meaning if I'm behind you in a car and I see you looking to the right ofetn then I might think you are turning right. you can also use body posture, like getting up out of the saddle and coast while using some other body posturing to indicate you will be changing direction such as looking behind yourself to see any oncoming traffic, etc. sometimes I will exaggerate my body posture such as by leaning back while braking (hard to describe).