Sorry for taking so long to respond, but I missed this. Breaking spokes at the nipple means one thing - the spoke is being bent, and that bending force is concentrated at the nipple. It happens because the rim wasn't drilled properly for the application and the angle of the spoke hole doesn't match the angle of the spoke. Or radial lacing is used where torque is being applied to the hub. The reason bicycle parts are so cheap is that they are made by the millions. It's rare (and therefore relatively expensive) to get rims custom drilled for bicycles, because normally the diameter difference between hub and rim is so large, and the variations in hub diameters and flange widths are so small that you can drill all the rims the same. (Those dimensions do become important for spoke lengths of course.) When you get to really large diameter hubs and their severe spoke angles, you can reach a point where a standard rim won't let you drill a hole at the proper angle. That's when you get into special rims like those with an inner flange, where the spoke is inserted in the rim and the nipple is in the hub. Or other, similarly unconventional rim/hub/spoke arrangements like you find on some big ADV bikes. Bottom line, spokes are meant for tension only. You don't want any bending forces at the nipple, either from incorrect drilling or torque from drive or braking forces. If you have radial lacing to a hub motor and you aren't breaking spokes, understand that the nipples are moving slightly in the rim (rotating in their seats) every time you accelerate (and brake if you have regen or a disc brake). The reason the spokes aren't breaking is that the holes have enough clearance to accommodate that rotation. So keep your eyes open for loose spokes. It's either that or you're gentle with your power and braking. High-power MTB applications with radial lacing like what started this discussion are asking for trouble.