I’m with chapaking.
I’m currently using a terra Nova thing that’s smaller (carries a co2 inflator and bottle only).
Been perfect for my spins, under 3 hours and near enough to home/car that I can walk back if it’s anything a co2 can’t fix. Phone and car blipper in shorts pocket.
Hoping that the camelbac will mean nothing in the pockets and I can pack a jic gilet in there to extend when I can use it. I only wear xc/roadie tops when I’m racing xc, rest of the time it’s baggier MTB tops (only the older ones have pockets and I don’t trust them on rough ground). The roadie wicking and lack of flapping is pretty useless on a slow moving MTB that’s only moving at speed for half the time (if at all).
I have a full pack for adventure spins, but it’s so nice just being out without a load of shite with me.