50 miles in a day. . . call it a 10 hour day, 5 miles per hour -- I run a 10K in about an hour, a little over 6 MPH. 5 MPH on a bike would be fairly easy, just a matter of mind over miles. Don't know how much water that would take, quite a bit I spose -- quart an hour sound right? More? Food, figure a few thousand calories, but if you go Austin's cycling calculator you can get a better estimate. CYCLING PERFORMANCE TIPS is another good read re energy output.