All good advise, but whatever you do, don't use the Elite VIP bottle cage mounts. They fall apart, typically dropping your bottle in front of your mates, and throwing the cage into the rear wheel. You might as well use cable ties (which BTW is also a seriously bad idea). I'd use a jubilee clip or just customise something from a strip of metal with a hole in each end and a bolt. Use a piece of innertube under it, to keep from scratching the frame.