A few years back when I wanted to increase my average speed on a mountain bike I tried many things - magic muscle juice from the local health food store, interval training, lighter components, stiffer shoes, shaving my head, bla bla. Finally I put a little sticker on the top of my stem, so it would be the first thing I saw when I was fatiguing and I dropped my head - it read "PEADAL FASTER, STUPID!!!" - and no joke it actually worked, I have those stickers on all my bikes now.