Calculating spoke lengths for new wheels


Staff member
I got an email question about the optimal spoke lengths for a new wheel build.
Listing the Rim and front & rear hub models.

I tried to reply by explaining all the how and why, not just giving the lenghts.
For calculating the optimal spoke length, we need the following info:
1) ERD (link to my article explaining how to measure it, in case the factory info is not 100% exact).
2) Hub dimensions (article explaining how to measure the important hub dimensions).
3) Spoke diameter (swagged 1.8 mm, or same-thickness 2 mm, or something third) - because thinner spokes elongate more, so you need shorter.
4) Number of crosses.

For the ERD, factory says: 583 mm

For hubs - this is my datasheet for the ones I've written down:

This is a decent online source that is often quite accurate:

Cross checked that with Shimano data:

And enter the most likely correct info into the spoke calculator, assuming 2mm spokes will be used, with 12 mm nipples.
Calculator used:

The results are attached as PDF files.

You can check the measurements yourself by following the instructions in the articles I've sent - I made some videos showing the procedure too.
I've done the calculations based on the publicly available data.

Based on those measures, and the calculation results, I would get:
Front spokes - same length for left, and right: 285 mm (if available) - if only even lengths are available, then 286 mm for 2mm spokes, or 284 mm for swagged (2mm - 1.8 mm - 2 mm - thinner in the mid-section) spokes
Rear spokes
Rear Left: 284 mm
Rear Right: 282 mm

This should start my Wheelbuilding playlist, with videos showing every step (long, slow, but in detail):

Let me know if you need any more info or explanations,


  • front-spoke-calculation.pdf
    178.3 KB · Views: 6
  • rear-spoke-calculation.pdf
    176.1 KB · Views: 5


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