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
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.
- 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
- 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
The code is hosted on github and is waiting for new issues and pull requests.
Wheelchart uses radar-chart-d3 for drawing the chart.