How to get information about the spoke size for an e-bike?

[psicopunk_]

Hi.

I have one a 29er ebike with a rear hub motor (Bafang RM G20 48V500W) and recently some spokes broke.
I am wondering if there is a table or something else that could help me find the specs of the spokes that I should buy.
I tried the vendor but they work mostly as a import/export company and are not really helpful on these technical issues.

I saw some sites with Spokes calculator but I thought that maybe there is some information already available.
Is this the only way to calculate the spoke size?

 

[docw009]

Spoke calculators figure the length for building a wheel. If you already have one, here's how the length is measured, although I believe the "G" dimension is measured at the threaded end, as you need the same gauge nipple there. The better spokes are thicker at the elbow, and thinner at the end.

Also, the spokes on one side of the motor may be a little longer than the opposite side. This is needed when the rim is not located in the center, which is what happens with a rear hub motor. It probably will not matter, but if you want to be accurate, use a spoke from the same side.