I took up quasi-serious riding about 10 weeks ago and I'm making satisifying progress, both in stamina and in speed. Whereas at the outset my rides were typically 13-18 miles with average times (including stops for lights, etc.) that amounted to about 13 MPH, now they are 20+ miles (and a few 25-40 miles) with average speeds just above 16 MPH.
I have no onboard electronics, so I know my speeds only after I come home and write down my distances and total travel times.
But here's the funny thing. For the last 3 weeks, almost all my rides (all but 2, actually) end up being between 16 and 17 MPH. If I feel like it was a fast ride, it's 16.x MPH. If I feel like it was not so fast, it's 16.x MPH. 18 miles -> 16.x MPH 38 miles-> 16.x MPH.
Make no mistake, I"m really happy about my progress, but I"m kind of wondering if there's some kind of barrier at about this speed that I"m going to need to overcome with time...