Can I enter the raw number from my tension meter?

Only if that number is already kgf. Raw deflection readings are instrument- and spoke-specific. Convert them with the official chart for your exact meter, spoke material, diameter, or blade dimensions before using this calculator.

Why are the left and right sides analyzed separately?

Rear wheels and disc-brake front wheels are often dished. Their flange geometry produces different average tension on each side, so comparing every spoke to one wheel-wide average can be misleading.

What target tension should I use?

Use the rim or wheel manufacturer’s maximum or recommended tension. This calculator does not invent a universal target because rims, spokes, nipples, hubs, and lacing patterns differ.

How much spoke tension variation is acceptable?

Park Tool treats spokes within ±20% of the average tension as acceptable. Because rear and disc wheels are meant to run lower tension on one side, compare each spoke with the average for its own side. DT Swiss aims to keep tension as close to the rim maximum as possible with the smallest possible deviation, so a tighter band such as ±10% is a stricter target. Choose the allowed variation in the calculator and it flags any spoke outside that band.

Does this calculator convert tension meter readings to kgf?

No. It has no built-in tension chart, because the conversion depends on the exact meter and the spoke gauge or blade size. Convert readings with the chart supplied for your meter, then paste the kgf values here.

What does coefficient of variation mean?

It is the standard deviation divided by the average, expressed as a percentage. A smaller value means the readings on that side are more uniform.

Does equal tension guarantee a true wheel?

No. Tension balance, lateral trueness, radial trueness, dish, and stress relief must be considered together. If you are unsure, have the wheel checked by an experienced wheel builder.

What is ERD when calculating spoke length?

Effective rim diameter is the diameter at the seated ends of the spokes or nipples. It is not the tire bead-seat diameter or the outside diameter of the rim. Measuring your actual rim and nipples can be safer than assuming a catalog value.

Why can left and right spoke lengths differ?

The two hub flanges can have different pitch-circle diameters or distances from the wheel centerline. Rim offset also changes the lateral distance to each flange, so the two sides should be calculated independently.

Spoke Tension Calculator

Analyze left/right tension balance, calculate spoke lengths from ERD and hub geometry, and see how measurement error changes the result.

Convert each tension meter reading to kgf with the chart for your meter and spoke, then compare every spoke with the average of its own side.

Wheel readings

Enter converted kgf values—not raw meter deflection numbers.

Left / non-drive side (kgf) Right / drive side (kgf)

Manufacturer limit (kgf)

Allowed variation

Important: use the rim/wheel maker’s limit. A generic meter conversion or target can be unsafe.

Paste at least three readings for one side to analyze the wheel.

Quick spoke length check

Calculate each side independently from measured rim and hub geometry. Dimensions are in millimeters. For the formula, rounding advice and a step-by-step guide to measuring ERD, use the full spoke length calculator.

Effective rim diameter (ERD)

Total spokes in wheel

Hub spoke-hole diameter

Rim offset, + = holes toward left / non-drive

Left / non-drive Flange PCD Center to flange Crosses

Right / drive Flange PCD Center to flange Crosses

Enter the measured geometry to see exact lengths, common rounding options, and ERD sensitivity.

Measure ERD with two spokes

Seat two spokes with nipples in opposite holes, pull them taut, and measure the gap between their ends.

Spoke A

Spoke B

End gap

ERD = spoke A + spoke B + gap.

Quick answer

Convert each tension meter reading to kgf with the chart for your meter and spoke, then compare every spoke with the average of its own side. Park Tool’s guideline is to keep every spoke within ±20% of the average; on a dished wheel, apply it to each side’s own average, and never exceed the rim maker’s maximum. Dished rear and disc wheels run lower tension on the left side by design.

Example: Left 105, 108, 103, 110, 106 kgf: average 106.4 kgf, every spoke within ±3.4%. Right 120, 118, 122, 119, 121 kgf: average 120.0 kgf, every spoke within ±1.7%.

Paste your kgf readings to check each side.

Summary

This wheel builder toolkit covers two connected jobs. The tension analyzer accepts kilograms-force (kgf) values converted with the chart for your exact meter and spoke profile, then reports variation and outliers separately for each side. The spoke length calculator uses rim ERD, spoke count, cross pattern, flange pitch-circle diameters, center-to-flange distances, rim offset, and spoke-hole diameter to calculate left and right lengths. Everything runs in your browser.

How it works

Use the conversion table supplied for your exact tension meter and spoke profile to convert each reading to kgf.
Paste the left-side and right-side kgf values in wheel order, separated by spaces, commas, or new lines.
Enter the maximum tension specified by the rim or wheel manufacturer, if known.
Choose an allowed percentage variation from each side average.
Calculate to see the average, range, coefficient of variation, and per-spoke status.
Investigate flagged spokes gradually and remeasure after every adjustment.
For spoke length, measure ERD and both hub flanges, choose the lacing pattern, then compare exact and rounded lengths.

Use cases

Balance spoke tension while building a bicycle wheel.
Document a wheel before and after truing.
Find unusually loose or tight spokes on either side.
Compare drive-side and non-drive-side average tension.
Check converted readings without uploading wheel data.
Calculate different left and right spoke lengths for a dished rear or disc-brake wheel.

Frequently Asked Questions

Last updated: 2026-09-14 · Reviewed by Nham Vu