Hi there,
Try the Wolverine Website for a listing of group rides open to the public. I've done a couple in the past, and they are a lot of fun. The routes are generally through neighborhoods, and along main roadways with little traffic. The best part is the nice people you'll meet who have the same interests in cycling as you.
Here is the website....
http://www.lmb.org/wsc/
Click on the link above that says "rides"