There is a very special prize for anyone that does it all in one ride.
There are a few Audaxes that cover close to 8,800m climbing in one ride (Bryan Chapman 600 and Kernow & South West 600 are both ~8,300m climbing and I've done both of them in under 40 hours) but if you definitely want to smash that total then this starts on the 21st (but is sold out):-
There are a few Audaxes that cover close to 8,800m climbing in one ride (Bryan Chapman 600 and Kernow & South West 600 are both ~8,300m climbing and I've done both of them in under 40 hours) but if you definitely want to smash that total then this starts on the 21st (but is sold out):-
http://www.aukweb.net/events/detail/14-393/
17,950m climbing over 1300km and 2.6 billion midges.