Nantes to Palermo tour 2009

It is totally flat against your back i have ridden well over a century with a camel back and had no problems it weighs nothing at all
and in terms of cleaning dont be stupid and put something sweet in and i have used mine for over 3 months with out a problem only filing and refilling it with water it will be fine

I cant reccomend them enough!

I only ever use water in mine and it still needs cleaning at least once a week.