I am trying to gauge myself for a group ride. I ride 15.4-15.7 mph on my computer, but that is with a lot of stop and go traffic lights, losing big momentum to traffic lights, basically lots of traffic. I handle flats in 18-23 mph comfortably and can hang on hills. I am in shape and will try to make strides on 25 mile rides and still keep ending up in the 15.x range.
The questions is this: what do the posted averages really refer to? Average speed on flats, overall ride average?