When building or truing a bicycle wheel, one should monitor two aspects:
- The wheel must be true.
- The spokes must be tightened equally (on each side).
It may be nontrivial to satisfy both conditions: when you
tighten all spokes equally, the wheel is not true! So you
need to balance between the two imperfections.
Folklore calls this "art". With this tool, you likely find that the term
"accuracy" is more relevant.
What does this tool do
When you input tension values, they are shown on a radar chart. This gives
you an overal picture, how much tension inequality you have and what are
the biggest "painpoints" (most overtightened or slack spokes). You'll know
better whether you should tighten or weaken something on your next spoke
wrench attempt.
What this tool does NOT do
There is no magic. This is only visualization of the data you already
have.
-
It does not measure tension. You need a tensometer for
that.
-
It does not show the deviations of the wheel. It only shows the spoke
tension.
-
It does not tell you which spoke to tighten/release. You must check the
wheel deformation (both radial and lateral) and make the decision.
Usage hints
-
Number your spokes. For rim brake wheels, marker on the braking surface
works good. For disk brake wheels, marker on white aluminium or white
corrector paste on black works kind of OK. If nothing else works, marks
on the rim tape are always possible.
-
Wheels with 2:1 lacing, with twice as many spokes on the drive side as
on the non-drive side, are listed by the spokes on each side, for
example "16:8". Number them from the first of two neighbouring drive
side spokes, so that the sides go drive, drive, non-drive, and so on.
- Do one round: measure all spokes and input tension values.
-
Rotate the wheel and record (or remember) the biggest "problem": radial
distortion (inside/outside) or side deflection (drive/non-drive). Record
approximate spoke number where it happens.
-
In case of radial distortion: deside, do you need to tighten/release the
spokes at the "problematic region" or to tighten/release all other
spokes. For example, if you have a buldge at about spoke 10, and spoke
10 is too slack, then spoke 10 should be tensioned. If spoke 10 is too
tight, then all other spokes should be released.
-
Typically radial distortions are most easily corrected
only when the wheel is not yet tightened much. When tight, even small
changes to spoke lengths - which are not enough to affect radial
bulge/pit - already result in significant left/right moving of the rim
section.
-
During each step, do only one half-turn by the spoke wrench. Repeat
until tension deviations are under 10%.
The author was able to build in practice perfect wheels: maximum tension
as allowed by the rim manufacturer, deviations under 5%, no visible rim
deflections.
Contact
The code is
hosted on github
and is waiting for new issues and pull requests.
Wheelchart uses
radar-chart-d3
for drawing the chart.