I get an upset stomach and feel sorta sick after a long strenuous sweaty ride if i don't load up on electrolytes beforehand. I am a super salty sweater, and lose a ton of salt & minerals during a harder effort ride, especially in higher temps. My solution is to buy powdered Gatorade mix and eat the mix equivalent of 1/4 gallon of powder before the ride, along with making sure i am well hydrated beforehand. If i don't have the mix on hand, a bit of straight salt works okay. Half of my bottles will also be filled with Gatorade i mix a bit strong, the other half is water. I usually feel good afterwards, and have a white crust of salt on my face from dried sweat! I think i am an extreme case of a 'salty sweater', but this is the only way i can take a high effort ride in the hot summer and not feel sick to my stomach afterwards.