Training & Nutrition - electrolytes -- how much

I am going on a 220-mile, 3-day ride in 3 weeks, and just recently have started taking training rides that exceed 3 hours / 45 miles. I've always relied mostly on water and Gatorade, but recently added Cytomax to the mix. I also have increased my calorie intake during rides, using a mix of bananas, powerbars, gels, salty nut bars, etc. It's amazing how much you can fit in those 3 back pockets!

I'm concerned about whether I'm getting enough in the way of electrolytes. How much sodium / potassium / calcium does the average rider need to take in per hour? Do I need to round that number up in light of my profuse sweating, which causes me to drink more fluids than most riders? Are there other electroylytes I should be looking at?

Thanks in advance for any input.

That depends on you, how hard, how hot, etc.

Try Enduralytes.
http://www.hammernutrition.com/za/HNT?PAGE=PRODUCT&PROD.ID=4037

And because you're splitting the ride up into 3 rides, you'll be hungry and you'll eat a bit more food than normal, which also means more electrolytes than normal, so I'd look at that too - salt your food, have some chips, eat vegetables, think about that a bit at mealtimes. Yumm.