Ken, I have not tried this. I personally do not think anything but carbs in liquid form will give your muscles the fastest and most usable energy if you are racing or riding at the highest effort "above endurance" levels. This would be things like Time Trials rides/races or record attempts of greater than 90 minutes. From what I have read and experienced your body still only has the capacity of metabolizing about 300 calories per hour regardless of your activity level. Breaking down your fat for the energy your muscles need is still relatively slow, but if you are riding at a lower endurance level, then that is pretty much all you body needs. The goal for long distance time trialing (for me anyway) of stuff like 100 miles or longer, is to drink liquid fuel (mostly carbs - but a good mix of other) so that the body has to use the least amount of energy to make that fuel usable to you for your effort.