They come in a few sizes- the standard one is 70 ounces (thats a lot of
water bottles). They offer an insulated version for hot weather. Never
freeze water in one, as it will crack the bladder. You do have to keep them
clean. Don't use soap, or you will be drinking soap forever. The best
thing is to clean them like an RV water tank. Mix some clorox bleach with
water and let it soak in the bladder for a while. Rinse it a ton to remove
the chlorine taste, and it will be fine.
Another thing to remember is the system was designed to be above the bike
riders head, (again, rider hunched down over the handlebars) so the water
would flow down hill through the drinking tube. The bike rider would just
squeeze the mouth piece with his teeth to get the water flow started. If
the thing is sitting on your back, and you are sitting upright, you have to
suck on the hose pretty hard to get the water out, while squeezing the mouth
piece at the same time.
At the AERC convention I saw something that made me laugh. A vendor was
showing a prototype "On board horse drinking system" that featured a
camelback. The hose from the water pouch ran down to a hollow bit (!) which
had holes drilled in it. The horse would then in theory be able to either
drink a little, or maybe just wet his lips while under way. (until the
water all dripped out) Interesting idea, but needs some more R&D.
You can get camelbacks at any quality bicycle store.
Nick Warhol