Yeah, the other thing is that normally if you're in a bunch you're pointing or shouting out hazards all the time. If i'm out on my own, i won't do that obviously. So if someone's decided to sit on my wheel and i don't know they're there, then i might swerve suddenly to avoid potholes without any indication etc in a way that i would never do in a bunch.
It's just knowing and trusting the folk you're riding with. You get a feel for how much experience different people have, or if they have a habit of dropping back a bit rather than sitting close to the wheel in front or being a bit erratic etc. And i think as well that it can catch people out a bit when you get a bit of contact in the bunch and not to panic and start wobbling about. It wasn't until i started doing a lot of group riding that i realised how often you end up so close that you're rubbing shoulders, or even bumping handlebars a little sometimes. Or it's quite common to get a hand on your back or shoulder just so someone can let you know they're there if they are passing on the inside or moving position when the bunch has got a bit cramped. It definitely takes a little while to be comfortable with all that stuff going on and stay concentrated on the road and your surroundings.
It's just knowing and trusting the folk you're riding with. You get a feel for how much experience different people have, or if they have a habit of dropping back a bit rather than sitting close to the wheel in front or being a bit erratic etc. And i think as well that it can catch people out a bit when you get a bit of contact in the bunch and not to panic and start wobbling about. It wasn't until i started doing a lot of group riding that i realised how often you end up so close that you're rubbing shoulders, or even bumping handlebars a little sometimes. Or it's quite common to get a hand on your back or shoulder just so someone can let you know they're there if they are passing on the inside or moving position when the bunch has got a bit cramped. It definitely takes a little while to be comfortable with all that stuff going on and stay concentrated on the road and your surroundings.
had a guy sit behind me for 4 miles yyesterday but he knew what he was doing! Wasn't sitting right behind me, moved to my right and that was perfect in case of any unexpected braking.. 
