WORKSHOP

WORDS & PHOTOS: Ben Wilkins

A 3 / 8” square drive precision torque wrench with reversible ratchet head and locking preset action, offering a range of torque range of 5-25Nm.

Why is it important to get the correct torque setting? A torque wrench enables you to apply the correct amount of tension, e. g. to a bolt. Bolts are like springs: when they are tightened, they flex and become slightly longer. The bolt resists the flex and in effect becomes a spring. The tighter the bolts are( staying within corre ct limits), the greater the spring pressure they apply to the various bike parts they’ re clamping together. If the bolt’ s over-tightened, it can bend( become permanently stretched), and therefore won’ t apply the right amount of clamping pressure which could in time cause the bolt to fail( break or loosen).

What’ s the best type of wrench to buy? A micrometer or‘ click’ style spring torque wrench is the most common for general workshop use. A 3 / 8” drive with a lower torque range( e. g. 5-25Nm) is a good choice, as it’ ll cope with most of the smaller bolts and fasteners that are typically found on a bike. For larger items, such as wheels, a 1 / 2” drive with a wider torque range, e. g. 20-100Nm or 40- 200Nm), will be needed depending on the bike( particularly the rear wheel nut torque spec).

When does a wrench need re-calibrating? A good wrench comes pre-calibrated within +/- 4 % accuracy, and a dated certificate to prove it. Under frequent operating

KIWI RIDER 93