Today I did an organized 50k ride. It went just fine, other than the fact I got a flat. But the SAG showed up while I was just starting to take off the wheel and they changed out the tube for me. Anyway, the ride had a long uphill at the start (category 5) and then was mostly flat, with a few minor hills. I felt great at the end and could have gone twice as far.
Initially I had planned to ride the 100k route but the ride was poorly supported and there were no porta potties supplied. I did not want a 65 mile ride with no clear potty stop so I did the short ride.
I was left at the end of the day feeling really energetic so I volunteered to take my hybrid bike to the grocery store for milk. The store is about three and a half miles away, mostly uphill, with an 8% grade about half way and total elevation increase of about 360 feet. I started riding and felt that I was a bit slow and actually wondered if my rear tire was low and stopped to check. Nope. Everything fine. I went up the 8% grade hill and was going slower and slower, feeling really whacked out. Nearing the top of the steepest grade I was feeling very jittery, like a "sugar low" but had no nutrition with me, after all this was a short ride to the grocery. The hill continued up for the final mile to the store and I was pouring sweat even though it is only in the high 60s out, and feeling like I would barely make it to the store. I got to the store and almost dropped my bike chaining it up. I staggered to the milk section, pulled out the milk and dropped it on the floor. The store was nice, I didn't have to pay for it. I went and bought a doughnut, not thinking clearly enough to know what to get and the case was right there. I ate the doughnut outside, waited a bit for the sugar to catch up, and rode/coasted to the motorhome. It took me a good hour and a half and some more food after I got back to feel mostly normal.
So, what do you folks think happened? I always think of bonking as running out of energy on a very long ride, not on a very short ride. After the morning ride I had a big lunch of burritos, chips, and salsa provided by the ride organizers. It was too much food so I skipped supper. I was going to have a small snack after I went to the grocery store.
