In stand dishing

Video courtesy of PSIMet Custom Wheels

Islandix customer Toby sent this video saying it helped him understand in stand dishing (centering). Thanks to PSIMet for posting it.

The first part of the video talks about inserting the wheel in the truing stand the same way each time taking special note of the axle orientation. The second part of the video demonstrates a deliberate way of using the truing stand — how the wheel is removed, flipped and re-inserted. It’s notable he doesn’t loosen the truing stand uprights at all, preferring to spread them against the builtin spring. Altogether the message is consistent measurement is important for maximum accuracy.

Islandix dishing with the Target Plot works the same way except there’s no need to adjust the indicator to zero since software takes care of it. The software is simple. It records two measurements and computes two facts: the difference between the measurements and the direction (for example the rim is dished 0.3mm to the left).

Digital dish

This video shows how Wheel Analytics can track wheel centering, also called dish. First the tool takes samples from both sides of the wheel using cues from the foot pedal. Then the visualization calculates dish at the same time as lateral and radial alignment. In the example above dish error is 0.10mm, which is a great result. In all it takes about 35 seconds to measure dish accurately and quantitatively. From this point the wheel can be adjusted and dish will be automatically recalculated without further setup (calibration stability depends on the truing stand).

In normal use perfect dish means a dish error of 0.00mm. If you’re building wheels with offset dish, then perfect dish could be some positive value. Cannondale Ai wheels, for example, have 6mm offset dish. Wheel Analytics accommodates these wheels seamlessly and is the only truing tool that can measure such wheels without adapters.

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Visual wheel centering

The Target Plot is a unified visualization of lateral and radial alignment, which helps reasoning about both dimensions at once. From version 1.2.2 it can track wheel centering too (the term centering is used because it translates better than the word dish).

How does it work? Wheel Analytics needs to learn the ideal/centered position of the rim. This can be established two ways, either (i) using a single lateral reference as you would with the Centrimaster v-block or (ii) checking two lateral references by flipping the wheel in the stand. The second method is universal so it’s the default and discussed here.

Initiate setup with the ‘c’ key on the keyboard or click/tap the scale in the bottom corner of the Target Plot. A dialog opens waiting for the first lateral reference. Rotate the wheel so the valve hole is at the lateral indicator and press the left foot pedal to record lateral position. Flip the wheel in the stand, rotate to the valve hole and press the foot pedal to record again. That’s it. Now when you snapshot the visualization, direction and magnitude of any centering error is displayed.

A good proxy for the accuracy of this method is the repeatability of position when you remove and re-install a wheel in the truing stand. Technique plays a role — tighten the wheel in the truing stand to the same degree with the same force every time. Do not overtighten. Better truing stands do a better job of resisting twist and deflection, which improves accuracy. More will be written on this topic in a future article.

The image at the top of this article depicts a real wheel built in the Islandix lab. With a bit of luck the wheel landed 0.01mm off center to the left. The wheel was built using a Park Tool TS-2.2 and Wheel Analytics 1.2.2. This result was externally verified with a digital dishing gauge.