I ride up to the limited exercise capacity imposed by my health problems. This is usually about 8-11 mph average depending which direction and which bike. Depends a lot on where I am with my blood pressure meds, hydration, and blood sugar. For some reason if I eat over some threshold amount of carbs it really kills me for hours.
I used to do 16 average on my fastest road bike, but never got any faster than that. I blamed it then on my weight, but in hindsight probably also my health problems lurking.
__________________
Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."