I lead a urban mountain biking group every Tuesday (Advanced) and Thursday (Beginner). If anyone is interested, it's 6:30 from Retro City Cycles. Tuesday is a fast paced ride (avg speed is 18mph) that's roughly 25 miles, while Thursday is a much more tame 15 miles distance and 13mph avg. Mountain bikes are encouraged for Thursday and required for Tuesday (unless you want to break your bike.) Helmet and lights are REQUIRED. No exceptions.