I've had this bike bag for about a month now on my mountain bike and it has been great. It's big enough to fit a bike tool, spare tube, set of tire levers, and phone inside. It is also quite waterproof. It has gotten covered in mud, and used during a brief downpour, and the contents inside remained perfectly dry. The attachment point on the back for a bike light is also a great additional feature.My favorite aspect of this bike bag is the buckle attachment system. There's enough slack in the strap that I can cram a lightweight wind shell under the buckle, which normally wouldn't fit inside the bag. It makes it easy to get to and stash away if the temperature changes while out on the trail. This bag has been perfect for me. Super easy to take on and off, big enough to carry everything I need, yet not so large it gets in the way. I also love the ability to strap clothing to the outside of it. I will definitely get another if I ever need one.