Have you looked into the Naragansett Bay Wheelmen at all? They have group rides pretty often and have route maps up on their website. I've never ridden with them, but I think the crowd is pretty heavily skewed towards lycra'd roadies. Providence Bicycle on Branch Ave also sometimes has rides and caters to the road biking set.

If you're interested in learning more about the biking scene in Providence, tune into a bike culture talk / call-in show I co-host on BSR, a student-community non-commercial station. Our show airs every Monday at 9:30 on 88.1fm or bsrlive.com.