About

I'm Ger, and I've been mad about bikes for years. I'm a developer by trade, curious and largely self-taught, so I love being self-sufficient with everything my hobbies involve. Over the years, through trial and error, I've kept learning and cementing what I know. Spoke Calculator is the tool I wish I'd had when I started building wheels. Back then I had a handful of separate tools I reached for depending on the job. This calculator is my attempt to pull all those scattered tools into one place, plus new features I'd missed when I started and decided to build, to make something genuinely complete.

Where this started

My wheelbuilding started on a forum. Years ago on foromtb, deep in a thread called «ruedas endureras a la carta. EL POST» (custom enduro wheels, built to order), I read enough people lacing their own that I stopped outsourcing it and bought my first set of spokes and tools. The first wheel was hard: there were a lot of concepts I didn't know and the process was slow. With that first one done, and the satisfaction of having built it from scratch, the second followed. I've hand-built fourteen-plus wheelsets since: folders, enduro, gravel, fatbikes, rigid steel, kids' bikes. And I still get the same quiet satisfaction every time a wheel's tension lands within 5% across the whole set and it runs dead true.

Ger riding an enduro bike into a rocky descent at a viewpoint, above a sea of clouds — Above the sea of clouds, on wheels built at home.

The tool almost everyone leaned on was Freespoke (kstoerz.com/freespoke), Karl Stoerzinger's free spoke calculator with its huge community-fed database. It's still up and running, it was my reference, and it's what helped me get into lacing wheels.

What this is

I built Spoke Calculator because I wanted to bring together what you need to calculate and build a wheel without hopping from page to page: exact spoke length, multi-tensiometer tension, a truing simulator, and an open hub and rim database I validate by hand. The same free spirit as Freespoke, plus the things I always wished it had: asymmetric rims, straight-pull support, and live visualisers that help you see the wheel's current state.

Data

Hubs & rims: geometry comes from the manufacturer's official specifications wherever they exist, and every value is hand-validated before publishing. Where there's no official source, it's flagged for review.
Tension: each conversion comes from the tensiometer's own published table.

How the numbers are made

Spoke length is pure 3D trigonometry, no approximations, and the formula and the intermediate values are shown so you can check the numbers yourself. Tension conversions come from each tensiometer's own published table, verified against the manufacturer source where one exists. Those figures are estimates (devices drift, rims differ), so always re-measure as you build.

Get involved

Build wheels and spot a number that looks wrong? Missing a hub, rim or tensiometer? Tell me. Corrections to the data matter most: accuracy is the whole point, and I'd rather you catch my mistake than the next builder inherit it.