London Spokes

Helpful Tips

Below are a bunch of things that may help you with calculating spoke lengths and other wheel related tips. If you have something to share please let us know and we can add it to the list.

Spokes are measured from inside the J bend to the very end of the threads, see the image below:

Spoke length illustration

ERD is the effective rim diameter in millimetres which is required to calculate spoke lengths.
Often a wheel rim will state the ERD on its label or it may be available on the company’s website. More often than not the ERD needs to be measured and we recommended that you do, since often the listed ERD can be incorrect.

Essentially, ERD is the furthest distance you want the opposing spoke ends to be within the rim, when the spoke threads have full engagement inside the nipples.
The following two YouTube videos can be very handy to understand what ERD is and some clever and simple ways of working it out.

Measuring Effective Rim Diameter

Measure Effective Rim Diameter (ERD) With Homemade Tools

Both of the above are quick methods that are highly likely to give you enough to get an accurate ERD measurement without much difficulty. There are loads of other handy videos available although they can become quite technical and lose the viewer quickly!
Let us know if you find some better content which we can share for others visiting this site.

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