VeloChampion Sonic Bike Seat Pack - Black The VeloChampion Sonic seat pack is a classic design to fit under the saddle but with the added feature of a detachable strap should you wish to store it in your jacket rear pocket. Its dimensions are have been developed to perfectly hold a 700c Inner tube, 3 tyre levers and multi tool. 1 Main compartment, Detachable Strap Matt Finish with carbon look PU PVC 130cm x 70cm x 40cm