I'm looking for a recommendation for carrying a 29" tube, multi-tool, CO2 inflator and a couple of cartridges on my XC bike when I don't use a hydration pack. I currently use a Lezyne seat bag but it bounces around on rough terrain. I don't want a seat bag that uses Velcro around the seatpost because it will rub on my shorts. I've thought about a bottle cage mounted storage device. Anyone have a good solution?