Road racing / crit racing unwritten rules

[Dr Teeth and The Electric Mayhem]

Hi
I am a MTB XC racer at heart (not very good and finish last though) but I also enjoy watching road racing on YouTube. A few things that I don't really understand though, is there seems a lot of rules and unwritten rules, etiquette that go on that doesn't seem to happen in XC MTB (perhaps it does at the pointy end).
Could someone run me through those and why they are important? I have watched a few clips where they aren't followed and it seems to cause friction, why don't the riders just go hell for leather, why is there rotation?

https://www.youtube.com/watch?v=67_u_roqViI

https://www.youtube.com/watch?v=UQVVg98fdfs

https://www.youtube.com/watch?v=fpVKGPKhT6U

I don't seem to see this in MTB at the races I go to, or the clips from those races, so just wondered why it happens on the road.
Don't want to start any MTB v road debate, just genuinely curious.

[Soloman Dodd]

Aerodynamics.
The lead rider is expending more energy than the following riders, so rotate till near the end.

[speedking31]

But if your team's sprinter is in the pack, don't rotate so that the lead group is disrupted and s/he can catch up for the finish.

[Dr Teeth and The Electric Mayhem]

So basically the pack have to take it in turns to lead the race and drag the others around? Do they have to do that, what’s to stop someone being a wheel sucker right till the end then sprints past?

[Ladders]

Dr Teeth and The Electric Mayhem said:

So basically the pack have to take it in turns to lead the race and drag the others around? Do they have to do that, what s to stop someone being a wheel sucker right till the end then sprints past?

No, no one has to take it in turns.

It’s a balance of being near the front of the bunch so you can move with any breaks that may occur and not left behind. Plus the further back you are the more you suffer from the concertina effect when you enter corners, which can mean your sprinting to keep up with the rest of the bunch.

IMO the best place to sit is in the top 10 of the bunch. Try to do as little on the front as you can get away with.

You also need to find out what kind of rider you are. Sprinter? Breakaway specialist etc. this will also determine where your best in the bunch and how you ride.