End of the day, locking your bike outside is a losing battle. Whether it matches up to an angle grinder or not is not really the point, it just prevents opportunist theft.
The goal of locking your bike is to ensure bits don't go missing. However, what you're really trying to do is protect your investment. Locks stop bits going missing, but they don't protect the investment. My bicycle was locked overnight at Bristol Temple Meads train station (which I wrongly assumed was a secure-ish location). The thieves didn't manage to break the lock, so instead they just vandalized the bike so that I couldn't use it either. I sort of wish the lock had just given way, at least that way the bike might have provided some value to someone, somewhere.
True - In Toronto downtown, locks don't do anything. Thieves come fully outfitted in hex key sets and pedal wrenches - and they steal everything - from rims to forks to pedals to front shocks, and chains (who steals chains??? - apparently the thief had a chain tool handy to break the chain).
Anything less than encasing the whole bike + lock + secure post in a steel case (like a bike locker) won't ensure that your bike will stay in tact.
The answer is to have a shitty bike with a good lock, been using a $200 beater for 4 years and it still got everything except the saddle got stolen once
>who steals chains??? - apparently the thief had a chain tool handy to break the chain).
Reusable joining link? No tools required. As to the point of doing it, well, I had the QR skewers stolen off my bike once. Stealing a chain makes at least as much sense.
I've been locking my bike up at Temple Meads for years without any problems - I (cynically) always try to lock it up next to a much more expensive looking one, or one with a weaker lock. Failing that, as deep into the centre of the mass as possible.
> "how heavy does the lock look" to "how expensive does your bike look"
Bingo. For around town, your best bet is a an old, anonymous looking city bike. Faded paint and maybe even a bit if rust can be plusses. No gearing is a plus too (I don't mean fixed gear bikes though). Many of the fancy locks listed in the guy's comment above cost more than my town bike itself.
One of the sayings I find amusing is that "Your lock gets heavier as your bike gets lighter", an acknowledgement that lighter bikes cost more and require heavier locks.
I lock my (very expensive) bikes out on the street fairly often, though never overnight. I only ever use 1 lock and a component protection system.
I use the Kryptonite New York Fahgettaboudit it secure the frame to some fixed street object of equal strength (newish iron railings are good, otherwise some London lamp-posts will fill this lock so perfectly that there's no leftover space for a leverage tool).
I'd be curious to see how this lock holds up to similar testing. It's probably not going to compare favorably to much heavier/thicker U-locks, unfortunately, though it does have some advantages...I use a U-lock through the rear wheel plus a rope cable to attach the front wheel. The front wheel would be easy pickings if it had significant value and a thief with a bolt cutter happened upon it. I've seen people use two U-locks, but that's a lot of hassle.
Anyway, it's a cool idea, but I have to agree I wouldn't trust it without some evidence of its abilities to withstand modern bike thieves with power tools.
I'm an avid cyclist, but I wouldn't touch this lock.
Here's what I would use: http://www.lfgss.com/thread17938.html
And sure, this one is lighter, but stopping my bike being stolen is far more important to me than how much it weighs.