cc-
i've found youre only limited by your saddle (and the parts that contact it). i still get real pain after about 85 miles, where you just cant find a comfortable place on the seat.
for distance, i worked up to it, did my first 34-miler when i didnt think i could, then did my first 70-miler when i had never before ridden that far, then did my first true century when i'd never gone more than 70 miles, then did four centuries last year and hope to do at least six this year.
i'm still looking for that magical saddle that is lightweight, long/narrow for racing, but still comfy for the long rides.
i know its out there . . . .
and my suggestion to you is to Just Do It, you'll be surprised what you can accomplish. good luck.
laurie
Brand New Orbea Diva | Pink | Specialized Ruby
2005 Trek Madone Road | Pink | Ruby
1998 Trek 5200 Road | Blue | Specialized Jett
???? Litespeed Catalyst Road | Silver | Terry Firefly