#BikeNite A3: I heard about the @cyclewr group rides from their e-mail newsletter. Unfortunately, that's one-way, individuals can't e-mail the group.
Several people who ride in the #Kitchener Sunday rides are here in the #Fediverse, but don't post much about the rides. The exception is @TrueCommunities (Hi!)
#CriticalMass used to have a website listing ride times and locations around the world (including #WaterlooRegion, but I don't know if that still exists.