[urq] Rear proportion valves

[Michael Williams]

In regards to the tilton and any other proportioning valves for rear brakes, they work in the same way as the stock one. They allow full pressure up to the point at which the valve is set, at which point it limits the line pressure. 

This is a BIG reason never to use them on the front brakes because when you would need them the most, they'll go away. 

Michael