I am 5'6" 140lbs and am considering this...
I am 5'6" 140lbs and am considering this pack for biking, trail running, short hikes and just hauling basic small gear. I am wondering if I should be going with the s/m size or the m/l.
Osprey packs are based on torso length and not height, but it is safe to say that no matter your gender, a S/M is a safe way to go (unless you know you have a super long torso for your size).
I'd refer to Osprey's sizing chart on their website. And as Kate said, that is based on torso length. I'd get out the measuring tape and refer to the charts, but based on your height the S/M should work fine for you.
Actually, for the Talon 11, the S/M and M/L sizes are not based on Torso height. According to the company's website, the difference is carrying capacity.
Size cu. in.
Dimensions for both: 19.5 x 11 x 7