A spoke wrench or spoke key is a small

wrench A wrench or spanner is a tool used to provide grip and mechanical advantage in applying torque to turn objects—usually rotary fasteners, such as nuts and bolts—or keep them from turning. In the UK, Ireland, Australia, and New Zealan ...

or tool used to adjust the

tension Tension may refer to: Science * Psychological stress * Tension (physics), a force related to the stretching of an object (the opposite of compression) * Tension (geology), a stress which stretches rocks in two opposite directions * Voltage or el ...

in the

spoke A spoke is one of some number of rods radiating from the center of a wheel (the hub where the axle connects), connecting the hub with the round traction surface. The term originally referred to portions of a log that had been riven (split l ...

s of a

tension-spoked wheel Wire wheels, wire-spoked wheels, tension-spoked wheels, or "suspension" wheels are wheels whose rims connect to their hubs by wire spokes. Although these wires are generally stiffer than a typical wire rope, they function mechanically the same ...

. A spoke wrench is sometimes called a nipple wrench, as it is the

spoke nipple A spoke nipple holds a bicycle wheel's rim to each spoke. The spoke nipple is a headed cylinder with threading on the inside through part of its length (there is an unthreaded lead-in nearest the "flats"). Traditionally, the nipples fit in hol ...

– not the spoke – that is turned in the process of changing the tension of a spoke.

Overview

Spoke nipples are typically T-shaped in

cross section Cross section may refer to: * Cross section (geometry) ** Cross-sectional views in architecture & engineering 3D *Cross section (geology) * Cross section (electronics) * Radar cross section, measure of detectability * Cross section (physics) **Abs ...

, with an internal thread running part of the way through the hole that runs along the spoke nipple's principal axis. A spoke nipple rests in a hole drilled radially through the wheel's rim, and the nipple is threaded onto the external thread of a spoke. The spoke itself is fixed, at its other end, through a hole in the hub. The spoke and nipple are functionally equivalent to a bolt and a nut. However, unlike a typical nut-and-bolt pair, a spoke and nipple do not join two parts (the rim and the hub) so much as bridge them, under tension. The area of the nipple around which the spoke wrench, or key, is fitted is generally square in cross-section. The tool grips the square of the nipple on either 3 or 4 sides; the latter type has a small cutout to enable it to be fitted over a spoke, after which it may be slid along to engage all four flats of the nipple. Gripping all four sides of the nipple results in less chance of rounding off the nipple than the 3-sided type, but is slower to use.

Sizes

Use

A spoke wrench is used during the assembly, maintenance, or repair of

bicycle wheel A bicycle wheel is a wheel, most commonly a wire wheel, designed for a bicycle. A pair is often called a wheelset, especially in the context of ready built "off the shelf" performance-oriented wheels. Bicycle wheels are typically designed ...

s to adjust the tension of the

s. The goal common to these activities is to bring the wheel (nearer) to the state of true — namely, a wheel in which the rim is: 1) a perfect circle concentric with the axis of the axle in the hub, and 2) planar, such that the plane of the rim is centered laterally between the two extremes of the axle where it is supported in a frame. A further goal it is to adjust the tension of the spokes so that they are brought as close to equal tension on each side of a wheel as is possible given the initial properties of the wheel's rim. This act of equalizing tension is called ''tension balancing'' and results in a stronger wheel. On modern bicycles, considerable space is needed for multi-speed clusters of gears as well as disc brakes; this means that there are usually two lengths of spokes on each wheel, one length per side. The act of shifting over the centerline of the rim between axle locknuts is referred to as ''dishing the wheel''. A wheel calibrated so that the planar centerline of the rim corresponds the vertical centerline of the finished bicycle is referred to as ''properly dished''. By increasing or decreasing the tension of individual spokes, or groups of spokes, around the circumference, a

wheelbuilder Wheelbuilding is the process of assembling wire wheels (generally a bicycle wheel, but including wheelchairs, and some cars). The components of a wire wheel are the rim, spokes, nipples, and hub. Goals The wheelwright must ensure that the wh ...

bicycle mechanic A bicycle mechanic or bike mechanic is a mechanic who can perform a wide range of repairs on bicycles. Bicycle mechanics can be employed in various types of stores, ranging from large department stores to small local bike shops; cycling teams, or ...

can correct for local deviations from true – e.g. wobbles, or hops.

Gallery

File:Kluc na spice.jpg File:Key for spokes.png File:Fahrrad-Speichenschlüssel 1792.JPG File:Speichenschluessel 01 KMJ.jpg File:0219-fahrradsammlung-RalfR.jpg

References

* Brandt, Jobst; ''The Bicycle Wheel'' {{Bicycle tools Wrenches Bicycle tools