Can someone who is good at riding bicycle automatically know how to ride a unicycle?

Personally I am good at riding bicycle. I can ride the bike hands-free while cruising/coasting (not pedaling) and turning.

I don't know about other riders. But for the first time (and second, third, fourth, fifth, sixth ... time) when I tried to ride the unicycle, I simply failed. Can't even sit on the saddle and relax and ride a few meters without falling down...

Riding unicycle require a complete set of new skills which are unique, though unicycle looks like half-bike!

While a tennis player can transfer some of his/her skill when learning to play badminton, a biker has to learn a completely new set of unique skill.

When a person is learning how to bowl, the skill can be divided into holding the ball, making a few steps forward, throwing the ball. These steps can be practice separately. But a unicyclist has to learn moving forward, turning and slowing down while balancing on a moving unicycle ALL at the same time.

Learning a whole set of new and unique skills will simply require a longer period of time.

So, is it difficult to learn to ride a unicycle?

Yes.
From day 1, I use the word "impossible" to describe every single skill that is required to ride on this dead horse. I continue to learn riding because I have nothing better to do during my free time.

No.
My body somehow learn those skills on its own without me realizing it. Quite mysterious. I guess the human body is pre-built with unicycling skill. All I need to do is bring myself to sit on the unicycle. The body can adapt and learn to balance on the unicycle on its own.

..........~*~..........

To be fair, I don't quite believe that all unicyclist can ride their bikes hands-free. And I am still quite lousy in doing wheelie on my bike. They require different skill set, so let's not mock each other and co-exist peacefully.