Lisa beat me to it, but I was going to mention the kid thing as well. Where I live, EVERYONE has kids. It is extremely family oriented around here. When we go on group rides, the men are mid-30s and up and the women are mid-40's and up.

DH and I discovered from many, many conversations with these recreational/club riders that these are the 'dads' and the 'moms' are at home with the kids. In fact, more than a few times I hear "she used to ride with me, but now she stays home with our children." The women who are out there with us, are usually past the age where their children are young. And, a couple riding together? Very, very few of us...I could count them on 1 hand and I have yet to see any other couples our age (late 30's).

That might skew the numbers a bit.