Glad you had a positive first experience.
For the benefit of any other juniors that might come across this, there are a number of ways group rides work.
One of the groups I ride with is an organized club. For these rides, everyone must have signed a waiver and in the case of minors, their parent(s).
Another group I ride with is nothing more than a bunch of riders who show up in a parking lot at the appointed time each week. We've had juniors show up or get dropped off by their parents who were not old enough to be home alone, without parental supervision. It's generally held that such instances place an undue burdon on the participants for someone to assume or accept reasponsibility for a minor we do not know. However, we have a few juniors who regularly ride in that same group with their parents. And, its been no problem for them to show up without their parent, even though they aren't legally old enough to be considered responsible for themselves. The difference is, that in these instances, one or more of us have a personal relationship with the junior rider's parent(s), have their folks phone numbers on our cell phones, know the riding abilities of the junior in question and whether they'll be able to keep up with the group they intend to join and whether they are familiar with the route, alternative roads back in the event they get seperated and generally have confidence in knowing a bit about them.
If you're an aspiring junior don't hesitate to show up at any group ride. But, don't be surprised if you or your parents are required to sign a waiver. Make sure to introduce yourself around and make new aquaintances. If you aren't yet old enough to be legally responsible for yourself respect that some riders may not want to place themselves in a position where they'll feel responsible for you or may be considered as having been such.
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Birth Certificate, Passport, Marriage License Driver's License and Residency Permit all say I'm a Fred. I guess there's no denying it.