Restrap City Loader Handlebar Bag – Fits Brompton Mount 20L Black. The Restrap City Loader Brompton Handlebar Bag offers huge storage capacity and is packed with practical features. Two fully waterproof fold-closure compartments offer up to 20 liters of internal storage. The main compartment is secured by an adjustable fastening strap with a Fidlock buckle which offers additional external storage for the likes of a jacket or dry bag.