I measured the temperature of my homemade battery 21700. The temperature is only 25 degrees. It was 8 degrees outside. The battery was insulated with foam.
Look at how beautiful it is. These guys have a lot of experience in creating bicycles. Such a light and modern frame could be made by real professionals.
I didn't notice the difference between the M820 and the M510. I liked the way the M820 rides. For the last six months I have been driving the M510 with reduced power up to 70%. I had to get used to the new motor :-)
The M820 engine is noisier than the M510 engine. The noise of the motor is very clearly audible. The M820 motor is about 30% weaker than the M510. I didn't understand how to turn on boost 95N mode. I drove 29 km on a 360W battery at 100% power.
I am sure that the manufacturers of CEF50 frames have extensive experience in the production of frames. The factory produces well-known brands. And the most important thing for a light bike is the frame weight of 2450g. We spend a lot of money on light parts, and we have to buy a heavy frame.