GLC, I'm about where you are at now, too. I really never did anything to improve my cycling speed, either. It just happened. I know if I start "training" it becomes a chore. I've always been more of an endurance vs. speed person, so I know to improve now, I have to do intervals. I have finally worked my way back to my cycling speed before I was sick 2 years ago, but I still have days where I am slow. I do intervals once a week on the bike, or try to keep up with DH on the flats and that helps.
All I know is that last year when I had to stop running for awhile, I was at a 10:00 or 9:45 pace and I'm still not back there, yet.