If you can run a marathon I'm sure you could ride 100k!
I was hoping to but it was always going to be a big ask to get fit enough starting at Christmas, and when that date turned into mid Feb due to poxy flamin' couriers it became impossible. Would still love to do it though - next year!
Good luck and have fun
I'm not really aware of any other big bike events except Taupo. Can anyone recommend other good ones, pref in the South Island?