I've bought a couple pre-owned saddle bags and a trunk bag system this year for my hybrid and touring bike, but so far nothing seems to fit right on my Dolce.

I'm looking for a under-saddle bag (or maybe a frame bag?) that I could use to carry a few tools and a spare tube. My goal is to outfit each bike with its own equipment so that I can just pump tires and go for a ride without readjusting bags. Any suggestions?