Substitutes the backpack. This big version allows to carry up to 4kg of weight at the seatpost. A little zippered inner compartment allows a save storage of important documents. Everything that needs to have a fast access can be packed into the zippered top-pocket or the two small side pockets. Furthermore it is possible to fix a small sleeping bag on the bag. A removeable shoulder belt allows to carry the bag in a comfortable way before and after cyling. It is suitable for a seatpost diameter between 25-36mm.