In reply to sammiKrogers:
Yes it will be busy but the bustle and vibrancy of the occasion is all part of the experience. If you want to hire a bike any time in October its best to reserve one before you go but there are still plenty of other options for getting around and away from the crowds if you want to. I was there throughout the festival period last year and even entered the open 2 day competition, all great fun, and for the 20 euro entry fee we got a goody bag with around 60 euro's worth of tee shirts, hats, chalk bags etc, plus a free meal and several free beers. If you want total peace and mountain solitude Kalymnos won't be for you at this time of year.