>>20 yard gap? 50 yard gap? at 30mph, anything over 1 bike length means you should start paying attention and perhaps go around the guy whos letting it open up. Once it hits 2 or 3 BL's get it closed<<
On paper. In reality it doesn't take much time before some dude just in front of you has allowed such a gap to open up - before you've noticed. It has happened to me plenty of times. And honestly, once it's over 50 feet and 30mph it's not always a closeable gap to be sure. But in those instances when I can't close it, I realize that the 30mph ride - while not 'over' my head that day - was probably sufficiently close to the edge of my envelope that maybe I deserved to get blown out - if not through sheer lack of strength then due to my own inattentiveness.
All part of Hammer University. I've been getting banged over the head by the faculty there since 1989 : ). The part of the original post that I found dopey was blaming this on some guy who's too slow to be on the ride. Wrong. It's YOUR job to watch for that like a hawk - and don't ALLOW that gap to form in the first place. Does anyone really think riders in these pacelines let this happen because they're lazy? That's not typically what I've observed. More like you need X horsepower to keep up and God gave you X-n horsepower, or that person may still be developing the power/experience to hang in the faster pacelines.
Oh yes, this 'don't ride with groups that are too fast for you' advice? Here's a newsflash: that's HOW we get faster, but riding with FASTER RIDERS. Which inevitably involves getting blown out the back door from time to time. So what? Ask any big time pro if they've ever gotten dropped. I think you'll find it's a typical bike racing experience for anyone learning the sport.