Cycle Repairing and Adjusting
With a Chapter on building a Bicycle from a Set of Parts

138 CYCLE REPAIRING H.B. Bowden stop clip ; 228, H.B.C. top cap stop ; 229, H.B.C. bottom plate ; 230, H.B.C. lever ; 231, H.B. top cap ; 232, quadrant back plate ; 233, quadrant front plate ; 235, quadrant front-plate screw. Armstrong gears can be supplied with any chain lines from lfV in. to 2 in. The standard chain wheels are 18- and 20-tooth, fdn- pitch, and 15-tooth, f-in. pitch ; but the makers also supply 14-, 15-, 16-, 17-, 19-, and 22- tooth chain wheels, f-in. pitch, and 13-, 14-, 16-, and 17-tooth chain wheels, f-in. pitch, if required. With 1-in. pitch chain wheels from 7 to 11 teeth are supplied. The width of chain wheels is f in., XV in., and 1 in. The high gear rises by 31 per cent., the low gear descends by 23 per cent, from the normal. The handle-bar control shown in Fig. 74 is a simple device which enables the rider to change gears without removing the hands. A slight thumb pressure in a for- ward direction brings into use either the normal or the high gear, whilst by slightly raising the lever it auto- matically flies back, first into the normal and then into the low gear positions. There is the alternative of a quadrant control for the top tube, as shown in Fig. 75. The Armstrong “ Central ” top tube control (Fig. 76) has a quadrant fitted through the top tube. Stranded wire is dispensed with, plated rods being substituted. In the gent’s machine there is a bell crank on the seat- pillar tube, and in the lady’s machine two bell cranks on the curved tube. The B.S.Ä. “ Three-speed ” Hub (Fig. 77) does not include a brake, but it gives a free-wheel on all speeds,