Storage at the rear of the saddle, with space for larger and wider objects. It must be especially waterproof and resistant because it is subject to mud and stones from the rear wheel. 

Goodto transport smaller, narrower objects, such as documents, tools and even food, since we will have access to it when pedaling.

Bag for small objects to have them more accessible when pedaling.

Larger bag, where we can store larger items, clothing and warm clothing. In many cases, you can fit a map at the top.