Castelli Undersaddle Pack

This bag is designed for the absolute essentials. You can comfortably fit one road tube, a set of tire levers, and a CO2 cartridge with an inflator head. It will not accommodate multi-tools or larger items.

No, it is water-resistant, not waterproof. While the synthetic material will protect your gear from road spray and light showers, it will not keep contents dry during heavy downpours or sustained riding in wet conditions.

The low-profile design and dual Velcro strap system are specifically engineered to keep the pack tight against the saddle rails. This prevents the pendulum-like swinging often found with larger, bulkier saddle bags.

While it is optimized for road bikes, it will technically attach to any standard saddle rail system. However, keep in mind that the capacity is very limited and it may not fit larger mountain bike tubes.

No, it features a single, open compartment. Because the space is so compact, items are meant to be packed together tightly, which naturally keeps them from rattling around.