Jul 3, 2026 · Ger

Build a wheel from start to finish with Spoke Calculator

This site has three tools, two databases and a glossary, and they’re meant to be used in a particular order — the order a wheel actually gets built in. This guide walks that path once, end to end: from a hub and a rim on the bench to a tensioned, de-stressed wheel and a saved build you can reuse. Each step links the tool it happens in.

0 · What you need

• A hub, a rim, and nipples (the exact ones you’ll build with — they matter for ERD).
• Calipers, a spoke wrench, and ideally a tensiometer — any brand, not just Park Tool.
• Twenty minutes the first time. If any term below is new, the glossary has all of them, in plain words.

1 · Get the numbers

The calculator is only as good as what you feed it, and two numbers dominate everything:

• Hub geometry. Check the hub database first — every record there is hand-validated against the maker’s specifications, and opening one drops it straight into the calculator. Not listed, or listed as unofficial? Measure it yourself with calipers: flange diameter (centre of hole to centre of hole), centre-to-flange per side, over-locknut width.
• ERD. The rim database gives you a starting point, but ERD depends on your nipples as well as your rim, and it is the number one source of wrong spoke lengths. Measure your own. It takes two old spokes and five minutes: how to measure ERD.

If your rim is asymmetric, note its offset (OSB) too — the spoke bed sits to one side, and each side’s length changes because of it.

2 · Calculate both lengths

Open the length calculator. Search your hub and rim — the pickers filter as you type — or leave them on manual entry and type the numbers you measured:

Everything a picker fills in stays editable, so overwrite the database ERD with the one you measured. Straight-pull hub? Flip the J-bend/straight-pull toggle and enter the maker’s per-side spoke offset (DT Swiss publishes it). The result updates as you type:

Two things to notice:

• Each side is calculated on its own. On a dished wheel the raw left and right lengths differ, though after rounding to 2 mm steps they sometimes land on the same size. And on a symmetric wheel (a rim-brake front, say) they come out equal. Use the two numbers the calculator gives you; never average them yourself.
• The result rounds down by default. A spoke that sits a touch deep in the nipple beats one that runs out of thread. The raw value stays on screen, and «Show math» opens the formula with your numbers in it — this is not a black box.

Before you order: name the build, hit Save, and Copy link. The link carries the whole wheel in the URL, so it works in any browser, and you’ll want it again in step 6.

3 · Order the spokes

Spokes come in 2 mm steps, some ranges in 1 mm. Cross-check against a second calculator if it’s your first build — Freespoke is the classic — and treat the first practical build as the final judge. The bench terms that follow (de-stressing, leading vs trailing and the rest) are all in the glossary.

4 · Lace, then tension with whatever meter you own

Lace the wheel (the calculator’s lacing view shows the pattern to scale, valve window and all), thread every nipple to equal depth, and bring the wheel up gradually — leading spokes, then trailing, never one section at a time.

Now the part where wheels are won or lost: tension. Hit «Tension this wheel» in the length calculator and it hands your exact dish ratio to the tension tool, so the left/right targets are already right for your wheel (on an undished rim-brake front, both sides share the same target). Pick your tensiometer — Park TM-1, DT Tensio 2, Unior, Super B, Wheel Fanatyk, Hozan, Birzman and more — and your spoke, then switch to measure mode: type a reading, press Enter, and the cursor walks the wheel for you while the radar fills in:

The rim sets your ceiling — use the rim maker’s published maximum for the higher-tension side and don’t exceed it. Evenness matters as much as the average: the tuning plan at the bottom tells you which nipples to turn and by how much, a quarter turn at a time. Re-measure between passes.

5 · De-stress, re-true, repeat

Grab pairs of spokes and squeeze hard, or flex the wheel against the floor. Tension will drop and the wheel will go slightly out of true — that’s the point: wind-up and seating you force out on the bench can’t undo your wheel on the road. Re-true, re-tension, repeat until the wheel stops giving anything back.

Want to understand why truing behaves the way it does before touching your own wheel? The truing simulator is a sandbox wheel: select a spoke, turn its nipple a quarter turn, and watch the neighbours, the dish and the trueness react live:

Knock one spoke loose and true the wheel back — it’s the most common real-world repair, and ten minutes in the simulator makes the real thing much calmer.

6 · Save it — future you says thanks

Wheels come back: a broken spoke two seasons on, a matching front, a friend with the same hubs. Everything on this site stores builds locally in your browser — nothing is sent to a server. Save the build by name, keep the share link with your order confirmation, or export the JSON file. When the wheel returns to the stand, one click restores geometry, lengths, targets and readings.

That’s the whole loop: measure → calculate → order → lace → tension → de-stress → save. The math is on screen at every step, and if a number looks wrong anywhere along the way, tell me — corrections to the data are the most valuable contribution this project gets.