tigat, if you've never raced, you won't be going up against the open masters for a little while. You have to start as a cat 5 even if you're 58. I've never seen a masters cat 1-5 field, and even if a race offered one, it's unlikely the fast masters would go anywhere near it.

Some races might have age group cat 5 fields, like maybe a 50+ cat 5, where you can race against age group peers with similarly limited racing experience. After 10 races you can upgrade to cat 4, and by that point you will have hopefully enough experience to know whether you want to race with the big boys or not.