In a nutshell: In Arkel's ongoing effort to provide the best innovations to our customers, we've created a Randonneur® rack adaptor for Brooks’ most popular  saddles. The challenge with Brooks saddles is the width between the seat rails. We've solved this with an adaptor that is much wider at the quick release point, where it attaches to the seat rails. The adaptor can be positioned vertically along the upper back part of the seat rails, or horizontally and closer to the seat post for when riders want to position the saddle further back (in the direction of the rear wheel.) This adaptor will fit all Brooks saddles that do not have coil springs suspension.