September 08, 2016 4 Comments
If wheel building were introduced today, but as a game, would it be popular? No VR but plenty of action: thrill of pursuit, unforeseen obstacles, counter moves by invisible players, presence of a formidable adversary, satisfaction of success.
Plus, the outcome can be ridden. Ka-ching! Wheel building has always been a game and its unpredictable challenges attract agile problem solvers. For many, the challenge of wheel building is compelling. Dependent variables exponentially increase system complexity. Tensioned wire wheels are elusive, almost intelligent, always unique competitors.
Builders select components, assembly is fairly routine, but adding tension, coaxing out instability, and getting it true is a lively, game-like process; no two sessions alike.
Success comes best by working with, not against, forces involved so minimal effort is required. Aikido, for example, depends on harnessing an adversary’s energy rather than inflicting brute force. Likewise, wheel components can be recruited to achieving a balanced, stable high energy state. A builder appreciates the forces and anticipates a changing script.
Most of us tension and finish a wheel by moving between two approaches: trueness and tension. Trueness can be seen and tension felt. Both are measurable yet a wheel may be finished without measurement of either.
Trueness and tension are interrelated but difficult to manage simultaneously. If superpowers allowed us to see both at once, a fair amount of wheel building complexity would disappear.
Most builders work primarily with trueness. Starting with slack, equal length spokes tightened down an equal distance, we then apply cycles of tighten-true-check tension (by feel at least), and repeat.
Truing corrections thrown down without appreciation of tension balance can create complicated, troubled wheels. Unravelling tension chaos, like untangling knots, can be nightmarish. Compound errors from a too-simple truing strategy create uneven tension in a structure that needs balance to be long term stable. Despair in a self-inflicted tension labyrinth brings an end to many a wheelbuilding career!
Speed up your Moves
The way to speed up building is to not lose appreciation for the tension subtleties in the spokes. It’s not only a question of length. To really accelerate building, try to watch roundness and trueness at the same time. Difficult but it directly affects speed. Roundness is a dependable indicator of tension. Three truing stand companies tried to bring this dream to their customers.
The Villum stand was everywhere in Raleigh’s postwar powerhouse factories. These Danish, cast iron behemoths offered a dial with roundness and trueness displayed over each other, like weapon targeting sights. If you tighten an already-tight spoke, you see a negative change in roundness as well as trueness. Builders are faster when forewarned if a logical correction produces negative effects (that must be sorted later).
At Wheelsmith in the early ’80’s, a Villum (imported to Palo Alto) made us suddenly fast and helped hugely to understand tension balance. No other stand compared. Var, in the same era, offered the Pérciray stand with two arrows that moved on scales giving similar insight.
Today, P&K Lie offer one of the only stands with this feature. Their dial indicators are non linear so rim movement is tracked from the earliest building stage. Standard dial indicators are too precise to use except at the finish. An untrue wheel makes them spin meaninglessly until the wheel is nearly perfect. Users of P&K knows what a huge speed boost these big, easily read clocks make. The stands are coveted for the speed they support.
Use Tension Directly
During truing, try plucking neighboring spokes for insight on local tension imbalance and use tensiometers if more precision is needed. When you find an imbalance, make your truing adjustments improve, not worsen it.
You can also build by tension and reserve truing for later. Sounds unlikely but here are two examples.
Building rear wheels from right to left is stunningly fast. First set tension, not trueness, on the entire drive side. This initial tension balance is fast to arrange when the build is young. Later truing goes quicker without tension troubles.
Zak's Clever Trick
A second example is owed to Zak Smiley of Skunkworks in Sydney. He discovered that stiff, straight rims (often carbon and more common than you think) can be brought to equal, nearly finished tension, ignoring trueness; tension verified by an accurate tensiometer.
A nearly finished wheel with even tension is, surprise, nearly true! Last step is truing, now super quick with nill effect on tension balance. Presto, a faster way to build. Experiment for yourself.
Lesson = explore strategies to bring better results. Keep refining your feel for tension and balance. All, even mundane, builds add to your skills and are opportunity for experiments. Let the Games begin!
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