Hi newbie here, very brief history, have been riding for 4 weeks, in that time I have ridden over 650 km.. I love this sport!! I'm 44yr 69 kg and overall pretty fit, however today feel like bad all over!! I had a day off, and family were off somewhere else for the day, and I had decided that I really wanted to try a 100km ride, had been slowly extending the length of my rides, with today being the longest ride, prior to this was 60km.. For nutrition, I had 8 Weetbix and 3 bits of toast, plenty of water before hand, approx. 2 hours before ride.. I took with me 3 bananas, which I ate at 20km, 45 km and 70 km and plenty of water, and everything was going fine, till I hit 80km, wow, it was like a sledgehammer hit me..I finally made it home, immediately had 2 pieces of bread and butter, a mars bar, then baked beans on 2 slices of toast, accompanied with lots of water.. I did my last 20 km in about 1.18 hour really struggling, and feeling that my concentration and skills very dropping. I was literally out of gas, nearly falling off bike when I had to stop at crossing paths or roads... Made it home, ate/hydrated and went to bed feeling rather ordinary, and have woken up feeling similar.. My aims were too complete 100km and keep pace above 20kph, which I did (so happy with what I have achieved), not the fastest times, but have to stop at quite a lot of lights, as I ride on a bike path that croses roads, several decent hills, and a very meandering bike trail.. Did I fuel up well enough? or is this too far too soon? Any thoughts or suggestons on what I perhaps could have done better, or not have done are most appreciated. Cheers guys.