I don't do Powerade or Gatorade unless I don't have a choice... it works but it's not very natural and clean.

My personal favorite mixes are Luna Pink Grapefruit or Cliff Shot Electrolyte Drink mix in Crisp Apple. Both are natural and mostly organic. I pick them up at sports stores but you can order them online. The Luna mix has less calories that would be great for a 20 mile ride.

Or if you want something straight from nature you can drink Coconut water... I like ZICO which is flavored with a little passion fruit and orange peel. yum. but ya gotta like coconut.

And about the HR monitor... yes you will acclimate....it's weird how your body knows you are doing something different even when it's use to physical activity.