Knew you would.

If you are interested in increasing your speed over time and you typically ride solo I find using a bike computer that gives average speed read out is a useful tool.

I tend to ride the same circuit a lot and will set my readout to the average speed at around the halfway point. With an acquired knowledge of what my average has been and should be I'll either have to start working like hell to catch up or just maintain and try to outperform the rest of the ride. I also work on my pedal cadence and try to keep my spin between 85 and 100 rpm. I use the wired Cateye Astrale 8 to give me this information.