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

22 CYCLE REPAIRING hardened. It is then as well to heat the bent part with a blowpipe, but not sufficient to discolour the plating. The crank should be removed from the machine, held in the vice jaws between lead clamps, and bent straight with a twisting wrench, the jaws of which should be lined with sheet brass to avoid damage to the plating. In Figs. 12 and 13, which show the B.S.A. disc-adjusting crank bracket and chain wheel, a and b indicate cups, and c the locking ring. Fixing Loose Pedals.—In all machines of recent make the right-hand pedal pin has a right-hand thread, and the left-hand pedal pin a left-hand thread, so that both tend to tighten up when riding. Still, there are hundreds of machines in use with old-pattern pins, both the left- and the right-side pins having right-handed threads. Various locking devices were formerly used to prevent the pins un- screwing when riding. If the pedal pin thread is a slack fit, the left pin in an old machine will unscrew in riding unless the locking device is very good. To remedy this, remove the pin, and, having heated the crank end and the screw thread until too hot to touch, well smear with Prout’s elastic glue. Then screw tight while hot, and lock securely. The pin will now be tightly fixed, and cannot be unscrewed unless heated. Hard Running Due to “Set” of Machine.—In the case of a bicycle which has been made up with a bracket of If in. and If in. hub, testing with a straightedge will show that the chain wheels are | in. out of line, and the machine will run hard, especially at first, in consequence of the chain binding on the sides of the chain-wheel teeth.