I recommend that you consult a doctor first because knee problems can be very serious. Regarding the electric bike – you just want to ride on it? There are models where you have to pedal, there are models where you can just sit. My husband has a model where he can pedal, he likes it, but he doesn’t use it for sports. If you mean an exercise bike, then that’s a good thing, where you can control the speed, the power, the type of trail – I’d love to get one to train at home. But of course, you shouldn’t forget about regular bikes like these, which in my opinion are the most useful, because you can breathe fresh air.