second end of detent spring 32 pushes against the bottom of square hole 7 a of adjust knob 7 thus detent spring 32 biases adjust knob 7 against detent block 33 in fig1 referring again to fig6 a first end of a hydraulic brake line 8 is connected to a handlebar mounted actuator 80 see fig1 and a second end of hydraulic brake line 8 is connected to brake assembly 50 in a manner that is well known in the art and is described as follows barbed fitting 30 has a barbed cylindrical portion that is received in the second end of hydraulic brake line 8 one end of a compression ring 29 abuts a tapered section of a bore in second brake arm 3 the top portion of the tapered bore is threaded and threadably receives a compression nut 31 hydraulic brake line 8 along with barbed fitting 30 is also received in the bore in second brake arm 3 compression nut 31 is tightened to a specified torque deforming compression ring 29 such that compression ring 29 hydraulic brake line 8 and barbed fitting 30 form a leak proof seal it will be understood that the connection of the hydraulic line can include any suitable connection referring to fig6 and 11 a piston 24 is received in a piston bore or cylinder 24 a formed in second brake arm 3 piston 24 has a circumferential groove in which is located a seal which may be in the form of an o ring 26 and a back up ring 25 a first end of piston 24 preferably has a tapered bore with a spherically shaped bottom against which is abutted a corresponding spherically shaped end.