Originally Posted by DAL1955 .
I started riding again after a long absence, so I was effectively starting from scratch. I rode for about a month alone and was doing pretty well I thought, an average just about 15mph (24kph). I located a local no drop group and on my first ride with them struggled through 35 miles at that speed. They were loafing and basically it was a recovery ride for them. Their advice, ride the big ring, pedal faster. Aerobic fitness was my issue so I started taking cycling classes at the local gym, wearing a HR monitor, and tracking my fitness. Once I started the classes (3x/week), and worked my a$$ off during them, every week I got a little faster. The weekend rides became measures of improvement, longer periods at higher speeds, recovery intervals and some hills. Fast forward to 3 months later, I completed a 62.5 mile group ride at an average of 29kph. My shorter weekend rides now average 30+. Its really a matter of how fast you want to go and putting in the work to get there. My goal is to be able to ride comfortably with the A group in our larger weekend local groups which average 23+mph. Best advice I got was to ride as hard as I could for as long as I could, slow down, recover, and do it again, and again, and again.
Also, if lactic acid build up is an issue, spin faster, but try not to slow down. Try to keep your cadence above 85-90 rpm. This works your aerobic systems and lets your legs flush out the lactic acid. You will find that you will gradually be doing 90+ and can shift to a smaller cog and go faster.
DAL