# Wheelwright

Software for tensioning bicycle wheels

Installing

# Using Wheelwright¶

Units

Tensions are reported in kilograms-force (kgf), a non-SI unit of force common in the bicycle industry.

1 kgf = 9.81 N

## Starting Wheelwright¶

Click on the Wheelwright icon or use the wheelwright command to start the application.

• Spoke Type: Find your spokes in the pull-down menu. For butted spokes, use the smallest diameter.
• Target Tension: Ideally, this number should come from the rim manufacturer. For most rims 110 kgf is a good target. Some manufacturers recommend slightly tighter spokes for the rear wheel, for example, 115 kgf.
• Target Accuracy: This is the accuracy you choose for your wheel. For a target tension of 100 kgf, an accuracy of 0.10 means that tensions between 90–110 kgf will be considered in-spec. (This in-spec region is shown as a green band in the plots.)
• Number of Spokes: This is the number of spokes on each side of the wheel. Wheelwright assumes this is the same on each side.

## Entering spoke tensions¶

Now you are ready to enter the tension of each spoke.

Pick a spoke and go around entering the deflection reading from Park Tool’s TM-1 tension meter. Wheelwright does the conversion to kilograms-force.

Interpolation accuracy

Wheelwright interpolates to find the tension (in kgf) for a given TM-1 deflection reading. Like all interpolations, this can be quite poor outside of the calibration range. Especially for small deflection readings (less than 10), the interpolated tension shouldn’t be trusted.

Which spokes you choose to call the right and left doesn’t really matter, although you might as well choose the drive- and non-drive-side spokes, respectively. Also, where you start (spoke #1) isn’t important, but starting at the valve hole is a convenient way to keep the spokes straight.

For a dished wheel — such as a rear wheel or a front wheel with a disc-brake hub — the tension will be higher on one side. You want the higher tension side to be within spec. Whatever tension the non-dished side ends up at isn’t important as long as it’s roughly uniform and the wheel is trued and dished.

## Spoke tension plot¶

The primary result Wheelwright produces is the spoke tension plot in the main window.

The spoke tension is shown for both the right (in blue) and left (maroon) spokes on the wheel. The spoke are numbered counter-clockwise. If you started with spoke #1 at the valve hole, it’s easy to locate a particular spoke.

Spokes that are in-spec (within the chosen target accuracy) are inside the green region. Out-of-spec spokes are also marked by a red square.

The dashed lines designate the average tension. The dished side of the wheel should be close to the target tension, and it’s pretty close in this example.

For this wheel, the left spokes are higher in tension than those on the right. This is typical of a front wheel with a disc-brake hub. The opposite is true for rear wheels, where the right (drive-side) spokes have the higher tension.

Five spokes are out-of-spec in this example; there are five red squares along the maroon curve. The largest errors appear to come from the spokes #13 (at low tension) and #15 (high tension). Radial truing will usually reign these in, so there is clearly more work that can be done on this wheel.

## Tension meter calibration plot¶

From the View menu select Show Tension Meter Calibration to open a window showing the TM-1’s calibration data for the chosen spokes.

The vertical green line is the deflect reading corresponding to the target tension. This is what you are aiming for on the TM-1 tension meter. In this case, a reading of 21.5 would be perfect, and anything between 19.5 and 23 is within the chosen accuracy. (Round the numbers to the nearest half, which is about as good as you can read off the TM-1.)

Notice the curve is non-linear. As your spokes get higher in tension, small turns of your spoke wrench can really increase the tension rapidly!

## Generating a report¶

From the Tools menu select Generate Report to save a PDF report of the wheel.

Here is an example report.

This could be given to a customer to quantify the quality of the wheel you built, or just hung on your refrigerator for giggles.

The first page shows the spoke tension plot, and the second page has a table with numerical tensions for each spoke.

### Customizing the report¶

You can add a header to the report by creating a configuration file named wheelwright.cfg or .wheelwright in your home directory.

Modify the header variable in the Report section, as in the following example.

# Wheelwright configuration

[Report]
header = **Main Street Cycles**, 123 Main St, Springfield, VA 22301