Last year, my daughter [16] and I [49] did the one day Seattle to Portland ride [STP]. It's relatively flat for 200 miles and we averaged 18.5mph. The year before, my son [16] and I did the same one day ride at 16.8mph. The first 100 miles we averaged 19.5mph. It is amazing what a tail wind can do to improve your average. Our yearly average was 18mph with my daughter [who weights about 80lb lighter than my son] and 16mph with my son [who has physical complications because of his autism].

Although we never considered it a race to anywhere, we did have some spirited training rides of +20mph averages. Lots of memories on those rides.