means of a bolt 63 which passes through the holes and is secured by nut 631 bearing surfaces 51 and 52 are also provided so that a pivot is formed by which the brake cable retainer 20 can rotate relative to the mount 10 the brake cable retainer is also provided with two concentric axial holes 212 and 222 a roller 40 is held in place between holes 212 and 222 by means of a bolt 61 and nut 611 the brake cable retainer 20 is also provided with a slotted hole 23 which along with the adjustable collar 24 and hollow screw 25 forms a housing for brake cable 7 the end of brake cable guide 6 is locked to the endpiece of the hollow screw 25 the end member 71 on the end of the brake cable 7 is held in place by recess 31 located in the brake handle 30 the grip 32 on the brake handle 30 and the recess 31 are similar to those found in conventional brake handle structure however the present invention additionally provides a platekike portion 33 which extends into the brake cable retainer and has a central hole 331 together with a cam surface formed on its periphery the brake.