I conduct cycling merit badge for my son's troop. Over 3 years I've learned that the boys need to ride all of the shorter distances with the troop before attempting the longer group rides. I'll pass on a lesson I learned the hard way - one boy showed up for a 25 mile ride and he had previously attended the Intro/Safety, Bike Inspection, and Repair sessions, but had done none of the group rides. I told him he would have to ride with the group on shorter routes before he could go 25miles. His mother raised a big commotion and wanted to see in writing where he was required to do the shorter routes. Two other Dads urged me to include him as he was strong enough to finish. The result was that he unexpectedly stopped suddenly with boys behind causing 3 crashes, luckily everyone continued but our "newcomer", who had enough road rash to justify being taken home. My process now calls for written sign-off of all shorter group rides before stepping up to more distance.