I don't race but I ride at a performance pace for long distances, My daily milage is always at least 50, most days more, on weekends I do long rides, every weekend includes 1 century, my longest day in the saddle 15.5 hours 218 miles in the hills of new england. I have 2 road bikes, a Raleigh technium, ultegra double (39 - 53), and a dura-ace cassette, ( 11 - 23) when I ride relatively flat land and (12 - 27) when I hit the hills, This bike has a relatively long wheelbase and I ride a 15 degree stem, this works well on long rides, my other and newer bike is a Bridgestone RB-T, which has a longer wheelbase and is more comfortable on long rides. The Bridgestone is my touring bike, the one I load up and go on, I built it using the new dura-ace tripple, (30 - 39 -53) and an XTR (12 - 34) rear. I find this gearing to be a great all purpose gearing, It likes to be loaded and it freights down the road when I travel light. Tires make a big difference, I find Continetal ultra 2000, 700-28C inflated to 110 psi to have good load carrying ability and low rolling resistance, straight wheels help also, I build my own wheels, I use ultegra hubs for durability, Mavic t-519 or 520 rims 36 hole for durability and wheelsmith 14/15 db spokes because I have never broken one. I have one wheelset with over 20,000 miles on it.
Oh, one more thing, Cycling is a very personal thing, ride what you want, go where you go, and wear what you what to wear, when you get to mile 100, the only one who will suffer or be uncomfortable with your equipment is you. what others think doesn't matter, it's all about the ride, and the ride starts at 100 miles.
Keep crankin