I came off my push bike at about 12 mph and that ended up with a fractured radial head - still pays up and sticks 20 years late; I can't imagine what it must be like to come off a M/bike at speed, leather are a must as your skin just disintegrates on tarmac. UK roads are in a poor state currently and I don't think they will improve any time soon, the repairs they do are part of the problem, a lot of them are falling apart the week after they do them.