Kryptonite New York Standard Bike U-Lock, Heavy Duty Anti-Theft, 16mm Shackle with Mounting Bracket and Keys, Ultimate Security…

Across the reviewers we read, the Kryptonite New York Standard is the lock people graduate to when they've either had a bike stolen or live somewhere they're worried they will. outdoorgearlab.com's testing reports that the 16mm shackle refused to bend or pull apart even under heavy hammer blows after an initial cut, and rates it virtually impervious to hand tools, cordless drills, and even car jacks, with the angle grinder as the only consistent defeat. Kryptonite's own 9/10 security rating is corroborated by that independent finding.

Specialist communities tell a consistent story. Multiple r/bicycling and r/BikeLA threads call it the absolute best lock they've used, while in the same breath complaining that it's heavy, bulky, and awkward to mount, one commenter joked it feels heavier than the road bike it protects. r/BikeLA users specifically note that the thicker shackle makes frame-mount brackets difficult to use, so many owners end up carrying it in a pannier or backpack.

The synthesis: if your threat model is professional thieves with bolt cutters and pry bars, this is the lock the consensus points to. If you're a recreational rider doing short coffee stops in a low-theft suburb, reviewers broadly agree it's overkill, and a lighter Mini-7 or folding lock will serve you better day to day.