A new fleet of lighter, comfier and more manoeuvrable hire bikes is on its way to London’s streets. The upgraded Santander cycles, known as “Boris bikes”, boast smaller wheels, a lower frame, a new gear hub and an improved gel saddle. The bikes begin to appear on London's streets from next year. After that, around 500 will be introduced each year as the older models are phased out. The new bikes are being developed by Pashley Cycles.