E Bike Wheels
I get a lot of E bikes with broken spokes in my workshop, sometimes with less than 1000km of use. My advice is to get your spoke tension checked at 6 monthly intervals or make it a regular job when you're cleaning your bike to just feel the spokes so you can spot any loose ones before they break.
Why do they break so often? Well my view on it is that the motors that drives the wheel produces high amounts of torque which puts a lot of energy from the hub through the spokes to drive the wheel forwards.
A number of factors on E bike wheels will magnify this wear:
Poor quality spokes is the most obvious one; good quality spokes from reputable companies such as Sapim & DT Swiss will perform more consistently and have more rigorous quality control.
Tyre pressure is a vastly under estimated thing with E bikes! If your Tyre is under inflated it will have a big impact on the battery life and distance you will be able to travel as the motor will have to overcome the rolling resistance that comes with a flat Tyre.
There are also other things to consider when choosing your E bike wheel and Tyre combination. If you have a nice wide rim with big volume Tyres fitted then any bumps and potholes that you ride over are nicely absorbed giving the wheel and spokes a much easier time.
Conversely if you have low volume race Tyres pumped up to 120psi or flat Tyres fitted then the spokes and wheel rim are taking all the shock from the bumps and potholes working the wheel extremely hard. I come across a lot of run flat solid Tyres fitted to E bikes because its the ultimate convenience right? No punctures, no checking pressures..... well guess what happens when you have a solid lump of hard rubber to absorb any road imperfections? It's pretty much like riding without a Tyre at all offering hardly any noticeable cushioning from the road.
Take care of your E bike wheels and Tyres!