I have two camelbak type rigs, which don't hold much, & generally use an REI Flash 18

minimal pack, but it is sweaty & shapeless. Looking for a pack that can hold a day's worth of stuff including a pair of shoes

has mesh/ airflow back panel, rides well on the bike, & is reasonably aerodynamic.

Maybe something like this: https://www.deuter.com/AU/ae/bike/ra...7318-blue.html

Suggestions?