Capacity
The total volume of the bike bag determines the amount of content that can be placed inside. When choosing according to this parameter, it should be borne in mind that a large capacity affects the dimensions of the bike bag. For use in the city, compact bicycle bags of a small volume are more suitable. They can carry personal items, repair kits and spare clothes. If you take a larger bag, it may well replace a backpack on a trip, which will relieve your back.
Rain cover
The presence of a raincoat in the kit - a waterproof cover worn on top of the bike bag. The specific design of raincoats can be different: in some models these are removable covers, in others they are non-removable "hoods" that hide in special compartments after hours. This feature significantly increases the bag's resistance to precipitation and splashes when cycling in rainy weather.