Just got back from NYC a few weeks ago, and spent a lot of time on my old 1974 Raleigh Competition!
I've been trying to formulate a coherent post, because so much has changed in the last 18 months that I can't even describe the situation in any way that makes any sense, but the headline is, the situation with e-bikes, bikes, and motorcycles had really devolved into utter chaos.
Here is what I observed, in order of insanity/dangerousness:
1) Motor scooters (Vespa types) driving 40 MPH (and probably faster) in dedicated bike lanes, absolutely zero enforcement. Saw this on Central Park West about five times. It's out of control, and incredibly cowardly-- like, you're using a bike lane because you're so scared of traffic, but you're okay with endangering bikers?! Probably, many of them are unlicensed, I didn't see plates on any of them, and this is by far the most dangerous behavior I saw.
2) Delivery folks riding the wrong way on one-way streets at 20-30 MPH around blind corners or cresting hills. Actually, I don't mind folks riding bikes or e-bikes just about anywhere-- wrong way, sidewalks, ramps, stairs, lobbies of buildings-- and in truth, I have done (and still do, on rare occasions) all those things on my acoustic bike, and I do them only in New York... however, I do NOT do that if I can't see what's around the next corner, over the next hill, or behind a parked truck. And when I do crazy stuff like that? I do it incredibly slowly. Like, slower than walking speed. That was the old school style: You wanted to be good enough so that you could almost come to a dead stop and stay on two wheels without your pedals hitting the ground. Well, those days are gone.
My last day, when I was worried about making my plane, I did ride down one street the wrong way very, very slowly... and as I crested a hill, there were two cop cars taking up the entire road. I slowed to walking speed, and rode between them. They didn't even blip the siren, not even a dirty look.
3) The mix of speeds on the park drives is now really too much. I hate to say it, but I really do understand the Class III distinction, and I think Central Park should be limited to Class II, or Class III bikes that are hobbled to Class II temporarily/electronically.
Yes, Roadies do go very, very fast-- it's depressing how much faster they go than me now, at my best, when I was in my 30s, I was at the lower end of the fastest 25% of riders. And the roadies are scary, and they do pass with inches to spare, and it is a little obnoxious. But I don't think it's actually dangerous-- most of those guys are really, really agile. It feels like they know what they're doing... the biggest risk is if I look over my shoulder and fail to hold my line... but those guys can anticipate that. (And I could, too, when I was one of them.)
What is dangerous is riders with no skills and little situational awareness riding bikes that are Class III or faster just ripping it up on flat sections. Even before these guys came on the scene, it was really a challenge to maneuver around little kids, people on (super slow) Citibikes, roadies doing 25-30 MPH on flat terrain, pedestrians, roller bladers, and the odd emotionally disturbed person running backwards against traffic or whatever. But the 30-45 MPH e-Bike thing-- and some of them are nearly silent-- does seem empirically dangerous.
Again, this is just my own observations and opinions, backed by absolutely zero scientific evidence.