I've done my share of group riding. I've seen a lot of riders grind on corners that I dont, and we are on identical bikes. I think what one of the previous posters brought up is valid, regarding rocket riders saying "when will Harley riders learn to get the weight off the bike." I call it counter balance. In a high speed corner you should be between the bike and the pavement, not on top of the bike. Im not much of an artist but heres what I mean.
Bike #1 on the left is going straight. Bike 2 and 3 are doing the same corner at the same speed but bike 2 is draging and bike 3 is not because the bike isn't at a sharp enough angle...
Another thing a lot of riders do without even knowing they are doing it...
At speed a bike doesn't turn like a car (duh). Meaning you don't try to turn the handle bars left to go left. The wheel is spinning and you use the gyroscopic force of that wheel to turn. You can either "push" the left grip to turn left or "pull" the right grip to turn left. The really good riders, like Motor Patrol guys will tell you to push into turns. The difference is what it does to your body position. Pushing left to turn left forces your body weight to go left. IE counter balancing the bike by putting your body between the bike and the pavement. MotoX riders may do it the other way, but their foot pegs are a foot off the ground and only 3 inches long. Plus they have tread on the sides of their tires. Plus they are almost coming to a stop in the middle of some of their turns. Road bikes need to keep the tread on the road and we are tryng to keep the metal off the raod, while trying to negotiate a curve and smoothly and as fast as we safely can do it.
I hope this makes sense and helps someone... I learned it the hard way.