Wheelbuilding glossary

The terms and jargon used across this calculator, explained in plain language. If a tool field or article ever loses you, it is probably defined here.

Spoke length & rim geometry

Spoke length: The length you cut or order, measured from the inside of a J-bend elbow to the threaded tip, or from the specified head reference for straight-pull. The calculator estimates it per side from flange diameter, centre-to-flange, ERD, spoke count and cross, with the relevant head correction. Left and right can differ, so they are calculated independently and never averaged.
ERD (Effective Rim Diameter): The diameter of the circle the spoke ends actually reach, measured to where the spoke seats inside the nipple, not the rim's outer or bead-seat diameter. It depends on the rim AND the nipples you use, which is why you should measure it yourself. ERD is the most common source of spoke-length error: a 1 mm ERD error moves each side by nearly 0.5 mm.
Offset / OSB (offset spoke bed): On an asymmetric rim the spoke holes sit off the rim centreline towards one side. With the appropriate orientation, that offset (OSB) can reduce the left/right tension difference; it does not necessarily make tensions equal. Check the offset and orientation so each side uses the correct flange-to-spoke-bed distance.
Dish: The lateral position of the rim relative to the hub, usually centred between the locknuts unless the frame or fork requires an offset. Unequal flange positions can require different spoke lengths and tensions, but rim offset, flange diameter and lacing also matter. Do not assume symmetry from the brake type or wheel position; check the dimensions.
Cross (lacing pattern): How many spokes from the same flange each spoke crosses on its way to the rim: radial (0x), 1-cross, 2-cross, 3-cross. The cross count changes spoke direction and length. Crossed patterns carry drive or hub-braking torque, but the pattern must suit the hub and rim and leave enough clearance. A rim-brake front may use radial only if the hub maker permits it.
Radial lacing: A zero-cross pattern where spokes run outwards from the hub without crossing other spokes. It is not a general choice for a flange carrying drive or braking torque. Use it only where the hub and wheel design permit it; a rim-brake front still needs hub-maker approval.
Rim channel (bed): The well down the centre of the rim where the tyre bead drops in to mount. A shallow channel on a wide rim helps a tubeless tyre hold air but makes it harder to fit.
Eyelet: A metal ferrule fitted into a spoke hole to spread the nipple load into the rim. An eyelet alone does not establish a higher allowable tension. Use the rim maker's limit and any specified washers, whether or not the rim has eyelets.
Hookless rim: A rim with no bead hook, just a straight inner wall. Common on modern carbon: the bead seats with an audible pop and the edge is stronger, but it caps tyre pressure and needs a tubeless tyre rated for hookless.

Hub

Hub: The centre of the wheel: the axle, bearings and the two flanges the spokes anchor to. Its geometry (flange diameter, centre-to-flange, width) drives the length and tension maths.
Flange: The part of the hub that anchors the spokes. Flange diameter is measured to the spoke-hole circle (the PCD), not the outer edge. Its effect on spoke length and bracing angle depends on the rest of the geometry and the lacing pattern.
PCD (pitch circle diameter): The diameter of the circle the spoke holes sit on, centre to centre, on a flange. It is the flange diameter the calculator actually wants, so measure to the hole centres, not the outer rim of the flange. Getting it right matters because it feeds straight into the length and bracing-angle maths.
Centre-to-flange: The distance from the hub centreline to each flange. The two sides usually differ, and that is what creates dish, so each is entered separately.
Bracing angle: The angle a spoke leans sideways from the wheel plane as it runs from flange to rim, shown per side (γ). It depends on flange-to-spoke-bed distance, ERD, flange diameter and lacing. With equal spoke counts on both sides, the side with the smaller angle needs higher tension for lateral balance; that is not always the drive side.
OLN (over-locknut dimension): The hub width across the locknuts, e.g. 100, 142, 148 mm. It locates the hub centre plane, but does not tell you the flange positions by itself; those dimensions are needed separately.
J-bend spoke: A spoke with a 90° elbow and a head that hooks through a round flange hole. It is the most common type and the easiest to replace. The elbow can flex and the head settles into the flange, part of why de-stressing matters.
Straight-pull spoke: A spoke without a J-bend elbow, designed for a matching hub seat. The lack of an elbow does not by itself make the wheel stiffer or eliminate settling and twist. This calculator replaces the J-bend hole correction with the maker's additive spoke offset for each side: positive means longer. A 1 mm change in that offset changes length by 1 mm; other dimensions do not share that 1:1 sensitivity. Check the maker's dimensions and offset convention.
Drive side / non-drive side: Drive side is where the cassette/freehub lives, normally right on a rear wheel; non-drive is the opposite side. The higher-tension side is commonly the drive side on a rear or the rotor side on a disc front, but check the actual geometry and spoke counts rather than choosing it from the name alone.
Freehub body: The part of the rear hub the cassette slides onto, with the ratchet or pawls inside (HG, SRAM XD and similar). Alloy freehub bodies get their splines chewed up by the cassette over time.
Points of engagement (POE): How many positions per wheel turn the freehub can catch the drive. More POE means a smaller dead angle, the free play before the hub bites when you pedal.
Pawls / star ratchet: The mechanism inside the freehub that catches the drive: spring-loaded pawls clicking on a toothed ring, or the pawl-less DT Swiss Star Ratchet (two toothed rings pushed together). More teeth gives more points of engagement. It changes the drive feel, not the spoke maths.
Centerlock / 6-bolt: The two ways a disc rotor mounts to the hub: Centerlock uses a splined interface and a lockring (fitted with a cassette tool), 6-bolt uses six Torx bolts. It changes the rotor and the tool, not the spoke length.

Spokes & nipples

Spoke: The wire under tension that ties hub to rim. Wheel stiffness depends on the rim, spokes and geometry. Adequate tension helps keep spokes from going slack under load; increasing tension is not a general way to make the wheel stiffer and can damage components.
Nipple: The small threaded nut at the rim end you turn to tension the spoke. Turning it onto the spoke raises tension. Nipples come in brass (durable) and alloy (light).
Butted spoke: A spoke thinned in its middle (double-butted = thinner centre, thicker ends). Lighter and more elastic, which actually helps a wheel hold tension. The thin centre is the section a tensiometer measures.
Bladed / aero spoke: A spoke flattened into a blade to reduce drag. It can still twist while tensioning; the flat section lets you hold it with a suitable tool. Measured by thickness × width (e.g. 0.9 × 2.2 mm); pick the matching material and profile on the tension table.
Spoke gauge: The spoke diameter, in mm (e.g. 2.0 / 1.8 / 1.5) or the old gauge numbers. It sets which tensiometer conversion column to use and barely affects length.
Leading spoke (ES: de tensión): On a crossed wheel, the spoke that leads from the hub in the direction of rotation (leans forward at the top). It stays relatively static under power and mainly carries braking torque. In Spanish we call it "de tensión".
Trailing spoke (ES: de tracción): The spoke that trails backward from the hub. It tightens under pedalling and carries the drive torque from hub to rim (the "pulling" spoke). In Spanish, "de tracción". Bringing leading then trailing up evenly avoids a localised hop.
Nipple washer: A small washer under the nipple head where it seats on the rim. It spreads the load on eyeletless rims and can cut galvanic corrosion, but it adds to how much spoke the nipple needs (often about 1 mm per side), so account for it when you set length.
Spoke prep / anti-seize: A thread treatment on the nipple. A dab of light oil or wax lets the nipple turn smoothly while you tension; anti-seize paste stops alloy nipples welding themselves to the rim by galvanic corrosion, which is what cracks them later. It is not grease and not thread-lock.
Thread-lock nipple: A nipple that resists loosening on the spoke thread. Sapim Secure Lock uses mechanical thread interference; DT Pro Lock uses adhesive. Mechanical locking does not bond the parts together. Follow the maker's instructions for lubrication, curing and reuse as applicable; neither system replaces correct tension or checks for spoke twist.

Tension

Spoke tension: The tensile force in a spoke, in kgf or newtons (1 kgf ≈ 9.81 N). Too little can let spokes go slack under load, encouraging loosening and fatigue; too much can damage the rim, spokes or nipples. The calculator's value is an estimate from a conversion table, not a safety certificate. Check the tool's calibration, use the matching spoke profile and follow the component makers' limits.
kgf (kilogram-force): Kilogram-force, a unit of force used for spoke tension, not a mass in kilograms. There is no universal target tension: use the specifications for your rim and other components. A maximum permitted tension is a limit, not automatically the build target.
Tensiometer: The tool that estimates tension. It does not read tension directly: it measures how far the spoke deflects under a fixed load, and a per-(device × spoke) table converts that to kgf.
Deflection: The tiny amount a tensiometer bends the spoke sideways. The raw reading is deflection (or a dial number), not tension, hence the conversion table.
Conversion table: A table relating readings to tension for a particular tensiometer and spoke profile. Some tables here are manufacturer-published; others come from third-party compilations, with source and version shown. The calculator interpolates between points and never extrapolates outside the table. Matching dimensions alone do not establish that a table suits your spoke or that your tool is calibrated.
Tension ratio: The lower-tension side as a percentage of the higher (e.g. 55%). With equal spoke counts on each side, the bracing angles set the ratio needed for lateral balance: the smaller-angle side needs higher tension. Unequal spoke counts change that relationship. The ratio alone does not establish a safe target tension.
Tension balance: Getting every spoke on a side close to the same tension, and the two sides in the right ratio for the dish. An even, on-target wheel stays true far longer than a tight but uneven one.
Tension log: A written record of every spoke tension reading on a wheel, so the outliers stand out and you can even it up.
Bottoming out: When a spoke runs out of thread inside the nipple before it reaches target tension. It means the spoke is too long.

Truing & building

Truing: Adjusting spoke tensions so the rim runs straight. Three things are trued: lateral (side-to-side), radial (up-and-down) and dish (centred between the locknuts).
Lateral true: Side-to-side straightness; a wobble is fixed by tightening spokes from the opposite flange where the rim pulls out.
Radial true (hop): Roundness; a high spot (hop) is pulled down by tightening the spokes there on both sides, a low spot by loosening.
Wind-up: The twist a spoke takes on as you tension it, because the nipple turns the whole spoke a little. Left in, it unwinds on the road and the wheel loses tension, so you relieve it as you build.
De-stress: Controlled loading of spokes during the build to help their contact points settle, followed by checks for twist, tension, true and dish. Follow a method suited to the components rather than bending the wheel forcefully. Settling contacts, removing wind-up and relieving residual stresses are related workshop tasks, not guarantees that the wheel will stay true.
Markling Method: In Reserve's "The Art of Wheel Building" (24 May 2023), John Petricciani credits Sam Markling with popularising this sequence: engage the threads on the outboard high-tension spokes, bring the inboard high-tension spokes to roughly two-thirds of finished tension, then work through inboard low-tension, outboard low-tension and finally outboard high-tension. It is a described workshop method, not a required sequence or a substitute for checking tension, true and dish.
Quarter-turn: The unit of fine tensioning: a 90° turn of the nipple. The tension tool plans in quarter-turns, but turns are estimates, so re-measure as you go.
Figure-8 (taco): A wheel knocked so far out of true sideways that the rim bends into an S (a figure-8), or folds flat (tacos).
Tie-and-solder: Wrapping fine wire around each outer crossing and soldering it, so the two spokes act as one at the cross. A traditional way to stiffen a wheel and limit tension loss at the crossing; mostly a tandem and track habit now, rarely needed on a well-built modern wheel.
Building by ear / by eye: Judging tension by plucking a spoke and listening to its pitch, or trueness by eye, instead of a tensiometer and stand. Experienced hands get close this way, but pitch depends on spoke length and section, so it is a feel, not a number. Use it to spot the outliers, not to set a target.