At minus degrees temperature my rear brake on my Radrhino 5 got stuck. This obviously is caused by the break cable hull ends upwards at the rear brake without a sealant. So water enters the hull and freezes at minus degrees within minutes.
Quite dangerous.
I solved this by funneling some defreezer into the hull and and sealed the enpoint with a chunk of lubricant.
This morning at minus 5 degrees breaks worked flawless.
I don't now if this same flaw exists at the new Radrhino / Radrover 6.

Thanks for all your suggestions. I wanted to use it in a very, very hilly area (alpine region). So without gears, regardless of torqu you have a bad time uphill and also downhill. So I don't think about it anymore.

Currently RadRunner is available with big reduction. The drawback of this bike is: It has no gears. What do you think, is it realistic to install a Shimano 7-gears or equivalent on a RadRunner?