I recently purchased a Timbuk2 Red Hook Crit backpack, and it is fantastic except for the length of the shoulder and sternum straps. When biking, they flap around and are an annoyance, so I designed these incredibly simple clips to keep the straps together.

The clips were designed to fit the 15 mm sternum strap and the 20 mm shoulder straps on the Timbuk2 Red Hook Crit backpack, however it was designed in OpenSCAD so it should be easily customizable​ to fit your needs.

The clip was designed in OpenSCAD and printed on a Makerbot Replicator 2 with 100% infill.