I find Strava helpful for this. Especially when I've done a big block of training and little racing. I can compare Strava segment times with people quicker and slower and then check our clubs race results to see where they sitting. That way I can get a rough idea of any fitness gains from my training. Strava can be a very powerful training tool.
I am also known to google my competition and try to cross reference them with strava to get an idea of my chances, or how much I need to improve my fitness before the event. This has tactical benefits by knowing what your key opponents are capable of