I give this bag five stars because it exceeded my expectations. I've used this bag for a few weeks and these are my observations. First off it's a nice looking bag. It appears to be well made. Good quality zippers and multiple d rings to attach things to the bag and it holds its shape even when empty. I do not have a sissy bar or a rack so I was a little concerned about attaching it to the bike. Not an issue . The supplied straps work very well and give the bag a nice clean look. I do have a grab rail on my seat but I think even with out the rail I could have figured something out. You have several options.Storage: I would consider this to be a day bag or a light overnight bag. It would be more than adequate to double as a gym bag and the straps make it very easy to remove from the bike. Maybe too easy lol. That is why I bought a retractable cable lock. It only takes a minute to secure the bag by running the cable through a d ring or two and secure it to the rail or frame. This will keep mostly honest people honest. Storage wise You have an expandable main compartment and two smaller compartments on either side. All three have pockets to keep things organized. The side compartments are not big but you can fit a lot of small things and keep them organized. For example in one side pocket I put two cell phones. a wallet , small flashlight , some keys, a leather man multi tool ,cable lock, insurance and registration cards and owners manual. The main compartment has a large mesh bag designed to hold the rain cover but you can put a few other things in there too without really compromising the storage of the main compartment. The main storage compartment when Not expanded will hold a light jacket or hoodie, a large half helmet , sun glasses and gloves with room to stick in some small stuff here and there. When expanded it will hold more but here is my only criticism. Even expanded you are limited by what can fit through the opening of the bag. So you may be able to fit six pairs of shoes or a twenty cans of beer but you probably won't get your full helmet in there. If they designed the bag so you could access the main compartment from the side as well it would have been better. That said I'm very happy with the bag. It looks good on my bike. Appears to be great quality for the money, and If you need to carry a heavy jacket or a sleeping bag there are multiple d rings and other place to strap a cargo net or bungee cords.