Surly Dummy Bags are designed to work with the Big Dummy cargo bike and other cargo bikes using the Xtracycle Longtail Standard. They were designed to provide the functionality and reliability you expect from Surly products. All materials, from fabric to thread to hardware, were chosen specifically for their given applications — as light or as heavy as they need to be to survive the battle against the elements and daily wear and tear. The 840d nylon exterior provides abrasion-resistance, while the tarp liner keeps cargo dry. Dummy Bags feature a roll-up rain flap, an expandable cargo flap, and a water-resistant inner pocket with an optional divider. Surly also included little details like stainless steel drainage and cinch cord grommets, replaceable cinch cords, and replaceable wear patches at the disc caliper and derailleur contact points. Dummy Bags work best with Surly Dummy Rails and Dummy Deck. Each piece will work with older parts — your Dummy Bags will play well with Xtracycle rails, for example — but fit and use of all features will not be ideal.