Today I ran and it was going great and I don't hold true to any real training plan I just run a lot and do a workout once a week or less and whatever but today I ran behind a stranger on a bike for a good several miles because it let me run a fair tempo pace. The man on the bike looked back at me a few times before I realized he was not comfort bale with my proximity and and relentless following. My question is how far back is it appropriate to follow people on bikes? And is it faux pas to follow bikes or runners you don't know?