You are passing cyclists. Blinking serves two purposes: you are letting them know that you have noticed them (so they know you're not just going to plow right through them) and you are letting them know you are going to pass them (so they don't do stupid shit like decide to turn left at exactly this moment).
If a car behind me, in the same lane, was passing me without blinking, I would highly suspect a drunk or overtired driver.
You are passing cyclists. Blinking serves two purposes: you are letting them know that you have noticed them (so they know you're not just going to plow right through them) and you are letting them know you are going to pass them (so they don't do stupid shit like decide to turn left at exactly this moment).
If a car behind me, in the same lane, was passing me without blinking, I would highly suspect a drunk or overtired driver.