Went for a 2hr cycle on my own this evening - nice evening for it, bit slightly windy which of course meant it felt like a gale out of the flat open areas around Cambridge. I obviously had it on my back for the first 40-50 minutes (20km), where my average speed was up on 31kmph!!!
That was up to the point where I turn westwards (I'm cycling in an anti-clockwise direction) in the screenshot below. Pretty uneventful, if tough for the next section of the cycle - the section around Needingworth was particularly tough - just long, straight and slightly uphill into a headwind. At this point my average speed had dropped to 29.3kmph.
Went slightly wrong at this point (almost ended up on the dual carriageway) and was starting to tire, so pace dropped a bit despite no longer being affected by the headwind. My knee's were playing up a little as well but soldiered on, my main aim to keep up the average pace.
Made it back to the start in 2hrs 15m, total distance 65km at an average speed of 28.9kmph. I think it's safe to say this is one of my fastest cycles (a shorter time trial may have been faster) - it'd have been nice to break the 29kmph mark, but will leave that for another day.