Hydration: Use a small backpack that can carry 2 (or more) h2o bladders to make up the capacity you want. You'll end up with 2+ drinking tubes but you could always get a 'Y' adapter and combine them into one. You could also attach some cages & waterbottles to your bike which should be good for 1 - 1.5lt of additional capacity.

Plan your rides so as to take advantage of places to top up your water enroute, which is what I do. Unless you live in the middle of the Sahara you shouldn't have too much trouble finding a source of water before going through 2lt.

Comparison of cycling and rrunning: Try a heart rate monitor. Your body will be making the same aerobic effort at the same heart rate so you could chart how far/fast you run v's cycle at any given heart rate.