Most of my races are in the 50-65 mile range and for me it really just depends on how hard of an effort I am putting out and weather conditions. I really focus on taking in a steady amount of calories and fluids leading up to the race, which can be somewhat difficult if the race falls at an odd time (10-noon seems to be difficult for me). I have done plenty of races on nothing more than a good steady intake of calories and fluids prior and 2 water bottles during and finished quite well, others I have to take a shot or 2 of gel (I always at least have a squeeze bottle with 2-3 shots). I would say that the majority of the time I do need at least 1 good shot of gel.
When I train it really depends on what my goals are, if I have some hard efforts towards the end and/or if the effort is hard the entire time then I usually take a bar or something in addition to 2 bottles of water and again fuel well before training. There are rides that I will intentionally push my body to actively rely on fat storage by not eating during a training ride, I have always felt that this allows my body to be better prepared to utilize all forms of fuel storage during a race event vs. relying on me to constantly fuel it, so I will sometimes go on nothing more than a pre-ride meal. Although these times are rare and those rides are typically less than 50-60 miles, but I have gone that long.
I did 100 miles not to long ago on breakfast before, took 2 bottles of water and then stopped briefly at 60 miles to fill both bottles with Gator-aid, and grabbed a breakfast cookie, a fig bar, another bar of some sort (I think a Payday), and some peanuts. I ate on the bike from 60-100 and never even opened the peanuts. I was hungry when I got done, but felt fine, and this was a pretty steady tempo the entire time (I think something like a 21-22mph average).