February 25, 2020 5 Comments
What does it take to build like a master? How does a master juggle so many variables to make truing into a smooth process?
Unfortunately, most masters can’t illuminate their methods because truing is a wordless series of hunches based on huge experience. Many thousands of adjustments and outcomes must be witnessed before a builder has a crack at mastery.
Wheel building has been learned this way for more than a century much as foreign languages are often learned through immersion. Repetition works but it’s not the fastest way and your expertise is limited by what comes your way. Repetition, as a teacher, can also lead to bad habits and boredom.
Is there a better way to learn besides sheer repetition? Yes, by first looking closely at the two dominant building methods.
ALL BEGAN WITH LIGHT GAP
Light gap (aka, 2D) truing is the overwhelming, dominant method. Movement at the rim is monitored by watching it relative to an adjustable caliper. As the wheel turns, a light gap between the rim and caliper grows and shrinks. The gap tells a builder how the rim is positioned. One can also use sound, with rim scraping against the caliper revealing its location.
This light gap method is called “2D” because it’s done in two separate stages: lateral (left and right) and radial (up and down). Each addresses two dimensions at a time. Anyone can learn it, a thumb or brake can serve as a caliper, no instrumentation is required, and humans are particularly good at it.
AND THEN CAME NUMERICAL
The second method is numerical, where adjustments are based on quantified rim movement. Call this “3D” because all three dimensions of rim position can be managed at once. This takes some help from the stand because builders can’t use their eyes independently like chameleons.
Here are three truing stands that enable numerical truing. First—the Villum from Denmark, historically used in huge numbers at Raleigh factories in the UK.
Then there is the Preciray from Belgium.
The third, and only modern stand, is the P&K Lie from Germany.
Each of these lets a builder see lateral and radial trueness at the same time, enabling fewer, smarter adjustments. Improvements can be made to BOTH at the same time. 2D truing involves chasing lateral run out, ignoring radial, and then switching to radial but disregarding lateral. With much practice, this back and forth becomes smooth but it requires more corrections, usually more time, and certainly more experience.
NOT QUITE 3D
Many bike shops have Park TS-2.2 type stands with dial indicator attachments. However, these do not allow 3D truing. The problem with dial indicators comes from their accuracy—two revolutions of the needle on a metric indicator is only +/-1mm of travel. If a wheel is not very true, say +/- 1mm, the dial will spin more than one full revolution per wheel rotation. While this is the actual run out of the rim, it is impossible to follow and to use for truing—too much needle movement.
This setup is useful only for fine truing when you’re nearly done or for QC on a finished wheel. To use indicators early in the build, Villum and Preciray have very large readouts. P&K Lie have designed and patented non-linear clocks whose scales display large travel at the edges and fine movement in the center. Clocks must be legible with untrueness of +/-1mm, so they can be used from the earliest stage of building which, by the way, is where the most time is to be saved. Example.
THE BIG ADVANTAGE OF 3D
3D truing reduces the number of adjustments. Radial runout is great for indicating relative spoke tension—bumps come from lower and dips come from higher tensions. Noticing this when lateral truing enables more effective corrections.
For example, when a left rim wobble is at two spokes, your best correction (without tension insight) is to tighten the right spoke and loosen the left. More often the rim is high or low at this left wobble, so a single adjustment to the tight or loose spoke is a better choice—evening tension while correcting both lateral and radial runout.
This is an example of the greater efficiency that comes from 3D truing. You can also pluck or measure neighboring spokes for insight. When the process starts at the earliest stage, when the wheel is maximally untrue, huge time reduction is possible.
We began using a Villum stand in 1981 without any training. After one year, no one wanted to build any other way. Wheels were not better but builds were faster and easier. I’ve heard similar testimonials with the Preciray stand and now, as a seller of P&K Lie, I hear it all the time. They sell because they are faster and easier for most, especially the less experienced. Claims of 20-40% time savings are common.
COMING—AN ELECTRONIC SYSTEM
Ryan Kereliuk of SpokeService.ca (site of the very popular, free spoke tension utility tool) is creating a system that takes TS-2 stands with indicators all the way to 3D truing. Later in 2020, he hopes to offer it commercially. Today it is undergoing beta testing and a set is traveling with me to the 2020 CABDA Show Technical Clinics.
Replace the dial indicators on a Park stand with digital indicators, connect them to Ryan’s box, and log onto the box's WiFi network with your smart device (phone, etc). You can watch 3D trueness on screen with either side-by-side dials (above) or a graphic plot display. The system auto-recalibrates for current runout and is easily zeroed. Stay tuned as this truly disruptive and enabling tech reaches market!
THE TAKE AWAY
Whether or not you use a dedicated 3D system, use these important insights in your building. Whenever making a lateral (side-to-side) correction, look for the related tension anomaly. Even the TS-2 side calipers have a notch you can line up with the rim corner to see lateral and radial at once. Awareness of side-by-side tension anomalies is THE key insight to building like a master. Using a 3D stand helps but awareness is the true enabler. That's how expert builders have made great wheels through the ages. This is how builders of the present can describe and share the process. For the future, few will remember the manual, light gap origins of our craft.
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