This bag fits not only a spare inner tube but also a CO2 pump and other tools. Deuters quality holds up on two wheels as wellthe brand known for its backpacks knows what its doing here too. - Front attachment wraps around the seatpost - Top attachment connects to the saddle rails - Main compartment volume: 1.1 liters, plus an additional 0.3 liters with the expandable zipper section - Outer fabric is made from recycled polyamide Some cyclists protect the bikes contact points with clear tape or protective film before using a bag like thiscertain surfaces can be quite sensitive to strap contact.