Wheel Build spoke length
To answer this question, you need some measurements.
The rim ERD, from the Ryde website.
The centre-to flange (left and right) measurements of the hub and the spoke hole circle diameter. These you may need to measure yourself as they are not always published.
This information is then entered into software (or a website) that performs the spoke length calculation for you. You could do this manually if you prefer but I often use the EDD spoke calculator or the one at kstoerz.com
Would you like any help making the measurements?