Sorry if this has been addressed before, but I'm new here......
After a reasonably long ride (~ 100 km say), I feel strong when I get home but I soon feel terrible a bit later. My pulse shoots up, I feel dizzy and weak, sometimes I feel cold, and I usually get a headache.
I used to think this was due to dehydration - but I was drinking tons of water. Next I thought maybe I'm losing too much salt, so I switched to a special drink (e-Load). Not a whole lot of difference, so now I've decided it must be insufficient food.
This then leads me to the question on what do you folks eat, how much, and when? Let's imagine you are doing a fairly long ride (80 - 160 km, or 50 - 100 miles). Don't be shy now.