@Alexez: I wouldn't worry too much. It's not a daily appearance that they fine for this... they probably needed some money. ;) My chinese colleague said, maybe they were fake-cops... but almost 20 guys on each side of the intersection with police-cars? C'mon! Colleague is riding a 80V bike, showed me his bike card (including the small plate on the bike) which means it got registrated with the Public vehicle and transportation guys which means it's legal to ride it. My old e-scooter bought in 2009 i got also registrated with plate (80V with a big sticker in front stating exactly that!) under my normal name. However, with the new bike they refused to issue the plate, but not because it's illegal... they just couldn't get their computersystem to swallow non-chinese characters. :)
In 2011 or 2012 i guess, there was big news that all e-bikes have to be registrated or else you couldn't drive. That news made the registration places nearly collapse with loads of people lining up in front waiting for the plate. So, not long after that they scratched the idea and since then you can carry your receipt for the bike and it should be fine.
If they really would ban all the bikes above 48V today, it will produce some big kind of public uproar i guess.
@Alexez: If you can find someone with residence address outside the 3rd ring who is willing to register the bike under his name, you can get it registered. Heard of that from other cities... but honestly, the time it's registered it is legally your friends bike and if it's not your friend anymore, that could be a bit of a problem.
@Alexez: When did you hear that? I had two motorcycles legal in KM, all two legally registered and later sold with no problems switching all the papers over to the new owner. Maybe it changed in the meantime, or it depends on engine-power. My biggest one was 250ccm, no probs. They did just hand out a list where you can't go in KM... almost every place within the 3rd ring road.