Wheel build for hub motors require unique considerations. Not only the rim needs to be built for extraordinary distribution of riding force dynamics but also the hub motor needs to have strong enough flanges to take the pull and push dynamics of the spokes.
Falco has continually evolved the wheel build. When we started we were using Buechel (www.buechel-online.com) rims from Germany back in 2012. They had angled spokes which allowed for straight angles for spokes. However, rims proved to be not as strong as we would have liked for hub motors. After continuous testing and riding, the rim had the tendency to split.
The second evolution of the wheel involved using Sapim strong spokes (https://www.sapim.be/spokes/butted/strong) which helped with the movement of spokes inside the spoke holes of the Hx motor.
In the third evolution, We used Rhyno Lite rims from Sun Ringle. These are extraordinarily strong rims. However, we could see further improvements possible.
In the fourth and recent evolution, we transitioned to Velocity rims and more specifically Cliffhanger rims (http://www.velocityusa.com/product/rims/cliff-hanger-559). We are also using Velocity Dyad rims upon request for narrower tyres (http://www.velocityusa.com/product/rims/dyad-622).