How Am I Doing?

Sounds like your on the right path, though 3 to 4 rides a week would be much better with some interval training thrown in.

I am 45, 5'10" 158lbs and can average 18MPH on 20mi rides. This
is my second season of serious cycling. I am approaching 1000 miles since April. I hope to complete 2000 before the snow flies
and the start of the ski season.

I would like to go head to head with riders my age just to see how I stack up. I got my butt kicked by a 14 year old kid this week. It was a humbling experience.

If you can manage 4 rides a week you should be able to make some rapid improvements. Don't sweat the weight - as you start to ride more and better it will go away!

Make one ride -- like your occasional weekend ride -- a longer ride of 2:30 or 3:00 hours. If you can find a local group ride you'll find that will help you to improve and you'll benefit a lot from the other riders.

Make 2 of the others moderate rides at 65 - 80% of your maximum heart rate. Stay in your seat for the hills allowing your heart rate to rise to 85% of your maximum, maintaining a climbing cadence of 60 - 70 rpm and spin on the downhills. Try for a cadence of 90 rpm on the flats if you can manage it, but at least 80 rpm or better. It looks as if your present rides are 90 minutes or so long and that's probably fine for now.

Make the 4th ride a 60 - 90- minute "spin" ride. Warm up for 20 minutes or so and keep your cadence at 90 RPM or so. During the interval --I'd suggest 5 minutes at first -- increase your cadence in an easier gear. 110 to 120 rpm or so would be great but you can work up to that. You can lengthen the interval time and add second and third intervals as you improve. The aim in the interval is to keep the pedal stroke smooth and supple and the cadence as high as you can manage without bouncing in your seat.

You can gradually increase your ride lengths. Don't add more that 10% a week and take the 4th week as an easier --less bike-time -- week.

I heartily recommend the Chris Carmichael Lance Armstrong Performance Plan book. It's great value and really sets you up for success.

Good luck!