Among the most commonly used hand signals by riders is for stopping or doing turns, one of which is when they raise their ...

This signal involves a biker putting their left hand up with the palm facing forward ... or there's some issue with the current leader's bike, because of which they have to leave the ride in ...

but in situations where a bike's tail lights or signals are malfunctioning motorcycle hand signals are essential. Unless it's at night, in which case hand signals will be much more difficult to see.