Калькулятор длины спиц

Wheelpro spoke length calculator

Wheel data

This table shows the information used by the calculation. It is the same data you entered, but presented in a clear and easy to read table. You are advised to check it and make sure it represents the wheel you intend to build.

Print help

Print the spoke table

You need to calculate a spoke table first.

Any text you enter here will appear on the print.

Warning, hub and rim names are incomplete.

Print help

This will print a reference document for use while you build your wheel.

On the print write down the spoke lengths you intend to use (my choice). When you build the wheel examine how good your spoke length choice was, and you may decide that something better is required if building the same wheel again (the ideal length). The alternative length is another length that would still build the wheel. The end result is that for this particular wheel you have two definitive spoke lengths. Keep the print for future reference.

If you want to adjust the margins on the print, then use your browsers Page Setup option, but do not use the browsers print function. When printing always use the Print button in the calculator because it formats the print content before printing.

How to round the spoke lengths

Always round the fractional spoke lengths up and never down.

The calculated spoke length will reach the point where you measured the rim erd, and you are advised to measure the erd using the technique shown in this guide. The calculated lengths are therefore the recommended minimum, so always round the fractional spoke lengths up. You can round up by up to 2mm, which means you can always find an even or odd size spoke length.

Here are some examples of how you would select an even or odd size based on the calculated length.

261260 on the even side is the absolute minimum, still okay, but 262 will be easier to build.
260.4262261Do not choose 260 for the even size because it will be too short.
261 on the odd side is the absolute minimum, still okay, but 263 will be easier to build.
261.2262263Do not choose 261 for the odd size because it will be too short.

Radial lacing

You should lace a radial wheel with the spoke heads out (elbows in), doing it the other way (heads in) puts more stress on the hub flange as the spoke is pulled over it. With all the spokes lying on the inside, the hub flange offset distance is reduced, and for radial lacing the calculator will subtract 2mm from your flange offset dimension. You can see this is the calculation log.

The biggest influence on spoke length accuracy is the accuracy of the hub and rim measurements, particularly the rim erd. If you use data found on the Internet, then there's a good chance it will be wrong, and so will the resulting spoke lengths. You should always measure your own components exactly as shown in the guide (click the headings in the data entry form).

Spoke head clearance

The distance between the spoke and the head of the adjacent spoke.

As the number of crosses increases, the spoke moves closer to the head of the adjacent spoke until it touches (clearance zero), then overlaps it (clearance negative). The overlap should be avoided because it puts an unnecessary bend in the spoke close to the elbow, and it also interferes when placing the spokes in the hub.

Spoke head clearance touching
Spoke head clearance overlapping

If the spoke head clearance is a small amount (say 0.5mm), then it still should be okay. Anything more than this then it's not advisable.

Note - the calculation uses a spoke head diameter of 4mm.

Spoke entry angle

The angle the spoke makes when entering the rim.

Spoke line entry angle

Standard nipples can swivel about 6 or 7 degrees. Nipples with a spherical design such as the Sapim Polyax and DT ProHead can swivel more (9 degrees for the Polyax).

For your hub, rim and spoke count, choose a cross pattern that results in a spoke entry angle of no more than 8 degrees, otherwise the stress on the spoke threads can result in fatigue failures (the spoke could snap at the threads).

Some rims are drilled at an angle to allow the spoke to follow the natural spoke line, in which case the spoke entry angle is not an issue. Examples of this are the WTB rims with 4D angled drilling.

Tension ratio

This is the ratio between the left and right side spoke tensions. For example, if the spoke tension on the 100% side of the wheel is 120kg and the other side is 60%, then the tension in that side would be 72kg.

This is for information only. When you build your wheel, this is how it will turn out. Tension ratio is calculated using the hub flange offsets and the spoke lengths. There is nothing you can do during building that will affect this ratio.

Left and right is from the perspective of the rider.

Left side

Sometimes referred to as the non drive side. For disc brake wheels, the disc rotor is located on the left side.

Right side

Sometimes referred to as the drive side (where the chain and sprockets are).

Triplet wheel

There's no calculator help for this option. Triplet lacing will be described in the next update of the wheelbuilding book.

Triplet wheel

There's no calculator help for this option. Triplet lacing will be described in the next update of the wheelbuilding book.






Save your data

Select the data, then copy and paste it into a word processing document or spreadsheet. A good choice is Google Docs or Google Sheets using a browser based on the Chromium source, for example Google Chrome, Opera and the latest version of Microsoft Edge. Other browsers may copy the data using a basic unformatted layout.

When you build your wheel, open the saved document and add any information that will prove useful if building the same wheel in the future, such as the type and length of spokes used. Do not edit the calculated spoke lengths, you need these as a reference to what the calculator recommended and what you actually used.

All output is shown below the data entry form.

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