I'm a huge fan of Nathan hyrdation vests overall, and this one is no exception. I use it frequently for long trail runs, hikes, and mountain biking. It performs well in all cases. I find that the vest rides very well both running and biking, with very minimal sloshing (I hated the old camelbacks for due to sloshing). In fact, I am almost as comfortable running with this pack as I am running with nothing at all, and I prefer it to carrying a bottle (except for very short runs).