KryptoniteNew York Standard Bike U-Lock, Heavy Duty Anti-Theft, 16mm Shackle with Mounting Bracket and Keys, Ultimate Security for Bicycles E-Bikes Scooters

For the price and the level of security of this u-lock (9 out of 10 rating), I recommend this for every bike rider even if you believe you ride in a safe environment. It has a 16mm hardened MAX-Performance shackle and double deadbolt locking mechanism. It just looks, feels and is a high quality tough u-lock. However it is an 8 inch shackle rather than a 9 inch shackle so that is either a good thing or bad thing. A slightly smaller shackle means more security as thieves would have more difficulty in using pry bars or jacks and it means less weight for you to carry (4.35 pounds). It is also means you may have difficulty to lock your bike on certain poles, bike racks or your locking method. If I try to use the u-lock through frame's seat tube, rear tire and post, it is possible depending on a small post but it is real tight. It may not work on some posts though. Here is another method that I like and would give more clearance for the shackle to a post... Use the u-lock through chain stay, rear tire and post. 3rd option? You could use the sheldon brown method and use the u-lock just on the rear wheel to post if the other methods don't work as it protects the frame and rear wheel. I still get nervous with the sheldon brown method because it doesn't take much time and effort to saw through a rear wheel with a handsaw and the thief could take the rest of your bike. Just try to fill the shackle so thief would have trouble with pry bar or jack. You should think about what bike racks and posts you use. As for the flexframe bracket... The lock is 8 inches and 4 pounds so it is pretty big and heavy. I can't even fit it on my bike because I have a water bottle cage connected on. I would rather just put the u-lock in a backpack. Maybe I would connect a Kryptonite evolution mini-5 if I had one as it much smaller and weighs a tad over 2 pounds? If you can use the kryptonite new york u-lock in a CORRECT, good locking method that protects your frame and rear wheel at same time, I would highly recommend it because it is a great u-lock. Also you could use a kryptoflex cable attached to the u-lock like I do and protect your front wheel. You can't be too safe.Update: I ditched the backpack and I installed the u-lock and the flexframe bracket on my topeak rear bike rack. Getting rid of the backpack with the locks and using a bike rack is making my bike trips much faster. I do recommend the flexframe bracket. I put it on a thin tube and it is tight. I also added nite ize rubber twist (thicker 24 inch twist) to bracket to add extra holding security. Those twists are really strong. The bracket won't be moving at all.

This is the most Kryptonite of Kryptonite locks, thick, strong, difficult to pick or cut through. Not impossible to defeat, used correctly, but about the best you'll get. Also, because of that: very heavy.What I don't like is the frame mount. No matter how it's mounted or adjusted, the mount (& lock) slides and pivots, often into the way of your pedaling, and with the size of the lock and the way the lock fits into the mount makes it difficult to impossible to mount out of the way (e.g., in the seat/cross/down post triangle).

I feel that my bike is super secure. This thing is heavy duty. It’s known far and wide to be a really good luck and when I went to lock my bike up my E bike that cost a lot of money I noticed that the bike right next to my bike had the same brand it was a lot older model, but it looked just as tough back then.

Great lock but boy is it heavy.

I did heavy research on all types of locks and ultimately went with a BELL 16mm U-Lock from Walmart for $24. worked OK for a month, then took me 20m to get it unlocked and it had not been exposed to anything harsh (snow, rain, dust...) during that time. There is no worse feeling than wondering if you're ever going to get home (or in my case back to the office from a lunch errand) when you simply can't get the tumblers to open up and you're being super gentle to not bend or break the key off. Spending an extra $45 hurt my pride and ego since I thought I'd be fine with the BELL lock, but the past 2+ months using this has been surreal.Lock mechanism is SUPER SMOOTH, feels very solid like you aren't at risk for bending/ruining anything. Heft and sheer strength of this lock is far superior to the Bell one which claimed similar stats (I bought the extra long U-Lock as well which was bigger but overall the same weight as this one). Attaches very smoothly to the bike, not harsh or cumbersome to attach around bike stations.Peace of mind is PRICELESS, I know it will open ever time, and lock quickly and without hastle.The only Con. You need to be close enough to a proper bike locking area given this is a standard size U-lock. the Extra long lock i had gave me more variety and always allowed for me to lock the front wheel as well as the frame to my pole/rack... This one you really have to pick your position or forego the front wheel and trust the cable (Abus flex cable 10mm) to do it's job. So far so good.