Originally Posted by roadcrankr

Nothing wrong with gauging average mph, especially as we advance in age.
My average began dipping at fifty. Typical rides cover almost 50 feet of climbing per mile.
This equates to climbing gradients in the 2%-4% range over my rolling terrain.
I cover nearly all my excursions as a soloist. The occasional groups only slightly improve my overall speed.
So, at sixty-four, I tend to average in the mid-15s on a forty-miler, with 2,000 feet elevation gain.
My area includes tons of over fifty beastly cyclists that can likely complete a flat 40k TT in under an hour. Sheesh.