Yep. The dense cities have more youngun's because cars can be so expensive and inconvenient, and there are alternatives to cars and bikes when you need them. The burbs have a different breed. Thank god for the old guys, some of them I can catch.
That's also what I see on my commute between Seattle and my home in the eastern burbs. As soon as you cross Lake Washington to the eastside, the average cyclist age jumps a decade and the ranks thin out drastically except for scattered roadies. There's a bump in the teenage bracket in the last few miles as I enter my neighborhood as the kids riding to the pool or basketball courts pop up.