Too many decaleurs accidentally release their bags when the road gets bumpy. C. S. Hirose developed a simple locking mechanism that prevents this from happening. Push and hold the button to release the bag. Then simply pull the bag upward, attach your shoulder strap, and take it with you when you lock your bike. Installing the bag is equally simple: Slide the rear strap over the backstop of your rack. Push and hold the button, then insert the two pins on the bag attachment into the tubes on the stem mount. Once the bag is in place, release the button to lock the bag. No other attachments are needed, yet the bag is held securely.
Note: The decaleur does not replace a rack: the bag still needs to be supported from below.