99% solo. That way I ride when I want, where i want and as fast as I want.
1% group for the social interaction. i'm a bit fast for a "B" ride and a bit slow for a "A". So i go on "B" rides and hang in the back to help sweep and take my turn at the front doing pulls.
BTW, there's not many people that are willing to ride when it's 20* outside.
