Not impressed at all.
If any of these tubes is aluminum (I'm 90% sure the seat down tube is), a battery powered grinder can cut through it in less than 1 min. Even a handsaw would need only a few minutes.
I don't think it would be useless, you'd just have to deal with the locked-in part - probably easy to pick - and then replace the seat tube.
So, first: I don't really know anything about stealing bikes. I've just built a couple from parts, and read articles about bike theft.
AFAICT bike theft prevention is really about deterrence. It's about slowing down a thief to up the risk of them getting caught in the act. If it turns out that these bikes are desirable (which, they don't look that way to me), and it's viable to cut the seat tube then deal with the locked part in a safe place? These bikes will get stolen.
What I don't understand is where a stolen bike like this one goes to get resold. There was an article here several months ago where a group in the US was tracking stolen bikes to a shop in Mexico, and it was especially upsetting because the guy was running his stolen bike shop in plain sight on Facebook. But they were all rare, customized, or otherwise high-end mountain bikes, multi-thousand-dollar bikes that enthusiasts dream about having.
This Yerka bike is not that, it's a boring commuter bike. 'Chromoly' steel can be a great material for a bike frame, but welded steel frames have been out of fashion for a long time. If this was using high end tubing, they'd be talking about the brand of it (i.e. Reynolds 853, not 'chromoly steel'). Most of the rest of the parts are standard low/mid grade stuff that are likewise not going to excite anyone.
The wheel locks are are also a gimmick. Not because they are easy to defeat - although probably are - but because the 3-speed integrated gear hub is going to be difficult to mate to most bikes, meaning this Yerka rear wheel is not going to be in demand. The front wheel is just a front wheel, not special, so maybe if those get stolen a lot then the Yerka ones are at risk? IDK.
This is not to say the Yerka bike is not a good bike, I just wonder if the nature of the bike is as much or more a deterrent as the frame lock and special wheel nuts.
Do you think the kind of people who steal bikes are smart, rationale and business savvy? That they are educated about this very brand of bike?
I've lived on 3 continents, and one of the sad common denominators is the stupidity and lack of respect for the values of things from low-life burglars. Music instruments thieves and bike thieves are the worst.
Sadly, there is one quality they often share and that is persistence.
If you know the specific value of even a single component on your bike you are in a tiny tiny minority of bike users already. That's cool me too. Just we should keep that in mind in this context probably.
It's actually pretty relevant. I got fed up of my bike being stolen in London so I bought a fancy anti-theft bike and a serious lock. The result was that instead of my bike being stolen in one piece all of the components were stripped off it, which wasn't really any better.
But the "use for themselves" thief is deterred with even the cheapest U lock (even with a moderately strong cable) as long as it's not trivially pickable.
First, if you saw through the frame then this bike becomes a lot less useful.
Second, essentially every bike lock can be defeated quickly by somebody who’s motivated with the right tools. Bike locks are theft deterrent, not theft prevention. Make it harder to steal than the bike next to yours and you’re generally good. Leave a bike locked up overnight in a high-theft area and you’re asking for trouble regardless of how it’s locked up.