running is bad for you
I am pretty sure mine is Nathan - I have been meaning to check for you.
But something like this I think will work well and not bounce (even though it's still a larger bladder): http://www.nathansports.com/hydration/race-vests/minimist
YAYpril - B-Plus
Do you know that Baboon character? I heard he also runs and bikes. You should PM him.
Mine is a Nathan women's one. Last year's version of this one: http://www.runningwarehouse.com/descpage-NIRV13.html It doesn't bounce at all. I love it.
I do like that one - I can throw my co2 pump in it......