I never have the expectation of being thanked or rewarded for helping someone, whether a cyclist, motorcyclist, etc. It's a karma thing. I feel good about helping. But then I've been a nurse since 91 so it's kind of in my blood.
BUT, if you help without the expectation of thanks or reward it just feels better if you do get a thanks. I always tell someone, to pay it forward, if I help them, maybe they can help someone else in the future. Just IMHO