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January 15, 2024
If you hang a J-bend spoke over a ruler edge it finds that point. A straight pull spoke will align itself similarly if pressed against the same edge.
Infering tension from spoke bending is the universal method. The relationship of tension and bending produces a curve whose center is the easiest to navigate—differences in tension produce similar bending change.
The chart below shows seven such curves for the WF tensiometer. These represent seven different spoke gauges. At the extremes—very low or very high tension—readings are less easy. They change either too fast or too slowly. In the center, the relationship is easier to read.
Tensiometers don't change the shape of that curve but they can determine where it sits on the chart. As you see above, the WF tensiometer makes the 40–100kgf area (shaded) most easy to read. It’s faster and easier to balance tension before a wheel is tight.
Also notice how closely bunched these curves are. No other tensiometer reads like this—nearly the same for different spokes. Bending is affected by force, material, and mass. We use a very low force, which reduces the effect of mass.
Winter is not the only playground for corrosion. Yes, there's more moisture but sunny weather's sweat, energy drinks, and lack of rinse can be just as punishing. So, what’s a smart approach to oxidation?
Read up on galvanic corrosion and minimize interfaces that are vulnerable. Also remember that corrosion, while relentless, is not explosive. The goal—minimize trouble, not eliminate it (you can’t). For example, here are rules that oversimplify—never use magnesium, never let aluminum touch carbon fiber, never use steel without paint, etc. Learn about these conditions so you can navigate safely. If you choose to ride a steel bike without paint—study measures that minimize problems. If aluminum nipples may contact carbon fiber—consider washers, use a tenacious oil coating, and favor deep anodizing.
The most common drivers of corrosion are moisture and salts. You can’t prevent getting soaked when it’s raining, but you can store your bike in a dry, warmer place. Salt on roadways and from our skin is unavoidable. But rinsing after exposure is very effective.
Conclusion: the more you know about the processes at work, the better you can be effective. Ignore simplistic solutions like:
Have you noticed the number of interesting tensiometer calibration fixtures? Most tensiometer brands offer no means to check or recalibrate. That's crazy! Below is an assortment of commercial and DIY calibrators. They carry a spoke loaded to a known tension so tensiometers can be checked.
In a perfect world, we could ditch the conversion charts that translate readings to tension. Tensiometers would be checked on a calibrator at the target tension of each build—that is all you need.
What if you cannot afford or find a personal tensiometer calibrator? There’s a simple, cheap solution—choose a wheel to make your standard and mark it . Number a few spokes, use a calibrated tensiometer to check them, and record the readings. Replace some with other gauges. The wheel’s trueness or tension balance does not matter. It will be accurate indefinitely.
In the future, when you want to check a tensiometer, take down your standard and see what the tool reads. You can use an uncalibrated tensiometer to build calibrated wheels!
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