same in road biking... a no drop ride means that the group stays together... and no one gets left on their own... I ride with a no drop group sometimes... what they do is ride like normal and then stop in predesignated areas to re-group... so when everyone is together they take off again... and if more than a couple minutes pass with someone still missing, a strong rider backtracks and finds the missing rider... it's a great thing to ride with a no drop group from a safety standpoint and also if you're a new rider! This ensures you get to ride with them... and typically they're not as "uptight" (for lack of a better word) as a race group!