I'm riding 9 miles to work and 9 again home almost every weekday. I can't really take much other time for intense exercise until January or February. At that time, my twins, now 9 months old, will be ready to ride in the trailer behind the bike. I want to be strong by then! I am weak now.

I want to make the most of the ride to work and back. I like riding hard on the commute and I've got a shower at work so sweating it up is not a problem. What I don't know is what I should do as far as interval intensity, alternating fast and slow rides, etc.

I think I need to build both strength and cardio ability.

My route is mostly flat. On the way to work, I drop about 250 feet right at the start of the ride. On the way, home, that climb is all right at the end. It's New York City, after all!

So let's hear it. Point me to links, send me to the stickies, or just help me out. For what it's worth, I'm not yet equipped with a heart rate monitor, and I'm not monitoring cadence electronically. For now I've got an old Avocet 25 that only really works as a stopwatch and speedometer. When I enter my stopwatch time into mapmyride.com, I show a typical average speed of 16 mph on the way in and 15 on the way home.

I'm 37, 6 feet tall, 178 pounds. I'm riding a Salsa La Cruz with slicks, clipless pedals, and I'm always in bike shorts. I know 9 miles is really only enough to get warmed up, but that's what I've got. Later this fall I'll be able to add a couple of longer rides each week, but for now, please help me make the best of it.

Thanks in advance!