mattj

i personally would go for a 26", especially as you say gapping etc is your sort of thing. As mentioned above, some people find getting a 26" under control difficult to start with, but through perservernace you will get there and reap the rewards. Also by the fact you ride a 24" you're obviously into your street riding, i'd expect you will be able to ride the street stuff you do at the moment (if you want to continue to do so) a lot more competently on a 26 than a 20, though i'm sure there are people who would argue the opposite. Having said all that it is a very personal thing. I know people who swear by their 20", however whenever i tried one i just couldn't get into it at all. If you can i would definitely try and ride friend's different bikes to get a feel and see what feels most comfortable to you, and what you feel will be most appropriate for the riding you aspire to do.

i was 14 and rode a mission trialsmaster. I haven't been able to bring myself to get rid of the frame, it still hangs proudly in my shed.

i did mine at an accountancy firm, it was mind numbingly boring