just returned from a 22 mile ride out. i didn't push myself too hard (just wanted to enjoy some quiet roads and the sunshine). had a protein shake an hour before i left, plus had 500ml drinks bottle on the bike. imagine my surprise when i stopped at a pedestrian crossing about 10 miles into the ride and felt like i was going to pass out i'd been drinking when i felt i needed it and didn't feel bad at all until that moment. i got off the bike and sat down on a bench in the shade for 10 minutes. drank more of my drink, managed to keep an energy gel down - i hate those things but they work - and felt normal again. got back on the bike and reversed my route - didn't feel at all bad on the way home and probably rode a little bit harder if anything. i'm not poorly so i'm wondering if i did something wrong or if it was just the heat hitting me all at once at the lights and my body struggled for a minute or two to sort itself out?