presure sensors in the brake lever and the thing that holds them (forget wat its called) transmit pressure signals through fiber optics to a main processor in the stem or possibly in the handle bar creat signals sent to the brake caliper which applies certain amounts of pressure. it will work in increments, feed bak would be the samw, cable could be mounted on sprigloaded spindles to provide acurat feedbak. it would work but it would be big and expensive