Hi,

I use the Camelbak 100oz Unbottle and use it for all of my rides longer than 15 miles. I attack it to the back of my (recumbent) seat, so I don't carry the weight myself and I only use water in it. I adore it and find it very useful for riding in the heat

For the metric century I just (barely...) completed, I put a lot of ice in it. When I was finished 6 1/2 hours later, the water was still ice cold.

I don't know that anybody has figured out how to mount one on a bike except for recumbents; that would make it much nicer for DF bikes...

Cheers,
Charles