How to use and navigate through SpokeCalc spoke calculator app.

SpokeCalc has been designed to simplify the use of a spoke calculator to a common, first time user as you will find it in the following tutorial. So let’s see what features are available in SpokeCalc.

Measuring the hub for wheelbuilding process. Bike hub dimensions.
SpokeCalc in action. Mobile friendly app for getting the right spoke length.


First step is to navigate to the proper wheel you are trying to get spoke calculations for. If you are calculating for the front wheel, make sure you enter measurements under appropriate section. On desktop you have separate sections for each wheel side by side while on smaller, mobile screens you will notice tabbed menu like one on the image below. This is important as the calculator’s algorithm differs between front and rear wheel when including measurement of OSB (for asymmetric rims).

Spoke calculator mobile menu. Switching the wheels
Mobile menu for switching the wheels.


The very next thing, that is important, is to specify the type of the hub you will be using by selecting it from the checkbox like shown below. Classic hubs use J-bend spokes, while the straight pull hubs like the name suggests use completely straight spokes.

Switching between wheels for calculating the correct spoke length.
The very first thing is to specify the hub type.

Now we come to the most interesting part, entering measurements. I have prepared some great features to help you here. First of all, by all means, do use tooltips (the white icon with character “i” in it) to trigger popup window with helpful imagery. Under these tooltip images, you will here and there find also ‘’Note: “ with some useful advice regarding this particular measurement.

In each input window you will also find appropriate unit reference. In general all sizes should be in millimetres! When entering decimals, please note that you must use DOT (.) and not comma. If in doubt about how to take measurements, please refer to my article on this subject. Precise calculation always depends on precise measurements you take of your wheel setup. You will find that sometimes you cannot only depend on data, found on the internet.

Input fields in spoke calculator
Example of input fields for front classic hub.


While we are covering filling out the inputs, it is normal for mistakes to happen. Therefore I have implemented two types of validation. One is non-intrusive and happens immediately after you enter a value. You will be warned as you go if you enter wrong value for example text, number that is out of range or you just forget to fill it out. Something like that:

Validating inputs before spoke calculation
Validating inputs before spoke calculation.

See the difference? Rim ERD’s obviously isn’t in the expected range and so the input will be styled with white bottom border and a little saturated background. Other type of validation is much more noticeable and appears after the click on Calculate button. You will get popup window with the problem input stated:

Popup for input errors in spokecalc
Popup will notify you of any input errors before the calculation.


Once you enter measurements and move to the last accordion, where you choose lacing pattern, the "CALCULATE" button should appear on your mobile screen. Before that you won’t notice that button whatsoever.

Calculate spoke length. Agree with disclaimer first.
To proceed and calculate spoke length you must agree with disclaimer.

In order to invoke a calculation, you must beforehand agree with terms of use. This step is mandatory so please read the disclaimer carefully and proceed when ready.

When you click on calculate button, you should notice calculations for left (non-drive side) and right (drive side). Right side is the one where your drivetrain is mounted. On your mobile these two fields should just pop up from the bottom. These are initial calculations, but there is more information available when you click on the graph icon below.

Calculate spoke length. Agree with disclaimer first.
After initial spoke length output, clicking on graph icon will take you to a more detailed section.

Once you do a calculation for one wheel you can easily calculate the second wheel without the risk of losing any data about the first one. In that way you can preview the whole wheelset setup and tweek the data to get different values or compare it with other setups.

You will also notice a RESET button underneath the main calculator section. When in need of a new calculation and you want to delete previously used values, just press this button and it will leave you with empty inputs.

Reset inputs of spoke calculator and start a new spoke calculation
Reset inputs of spoke calculator and start a new spoke calculation.


Most of you will probably end with the initial calculations as arguably it is the most important output of this spoke calculator. However you can continue by clicking on this graph icon and your wheel’s setup will show with in great detail.

Specifications of your wheel setup.
At the end take a look at your wheel setup. Give it a try!

Here you will find your input data stored in a table, spoke length for both sides and below even some tensioning references. Compare different setups' specifications by mixing and matching different components or by just printing out the wheel setup sheet. Give it a try!

Do you have any more questions? Please refer to my FAQ page in the main menu or leave me a comment on [email protected]

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NEW!!! We've just released a total wheelbuilding tool. Calculate spoke length, save components, calibrate tension meter and use tension app.