When I first started riding and was too nervous to reach for a bottle while riding, I tried riding with my Camelbak a few times. It didn't work out very well for me at all. In a road position, the Camelbak ended up making my hunch up my shoulders, leading to tension and discomfort. This may have been just a personal quirk, it may work well for other people, but I didn't like it at all (and I have no problem taking my Camelbak on long runs).