I'm trying to increase my average speed. For a couple of years now I've been achieving about 18mph ave speed over say 25 miles on rolling terrain, only for this speed to disappear over the Winter.

However warmer weather is on it's way so I really want to get closer to 20 mph this Summer - but how do I go faster? Every week I do a couple of 40 mile rides and three 25 mile rides over rolling terrain - as fast as I possibly can.

Anyone got a training routine that they would like to share?