The usual way to carry bikes on a bus is on a shared horizontal rack at the front. The problem is when someone gets off, their bike is invariably at the back,

The usual way to carry bikes on a bus is on a shared horizontal rack at the front. The problem is when someone gets off, their bike is invariably at the back, and so they have to remove all the bikes stored later, get their bike off, and put all the others back on. This takes many minutes, which makes it infeasibly slow for commuters. A better rack design (hanging vertically on the rear?) could solve this.