Kryptonite New York M18 U-Lock

Expensive but visibly hefty and famously reliable. Very tight fit can create challenges when locking bike to a chunky post or stand (my frame is quite chunky too). Would recommend having a chain as well

Big yellow visible deterrent

This lock is big and heavy, at 2.7kg it stays at work so I don't have to lug it about everyday. I work in a place of high student occupancy, so bike thefts are a big problem. Putting this lock on the bike each day makes me feel sure that my bike will still be there for my commute home. I double it up with the kryptonite series 2 and cable through the front wheel and frame. The series2 is light enough to carry round for popping into shops on the way home.I think any thief looking at my bike is going to look for easier pickings after spotting this lock.

Excellent Security. Rated 10/10

This lock is heavier and thicker than the equivalent Kryptonite lock anyone can buy in a store and in the same price range. It's available in Europe so it's a bit tricky to get hold of. but worth it.

Heavy duty protection

At the end of the day if someone is really determined to steal a locked bike then they probably will, however the use of this lock anchored to an immovable object is pretty much as good as it gets when it comes to cycle lock security.Lock action is silky smooth with a sliding dust cover to keep grit etc out of the mechanism. 18 mm hardened steel that will thwart anyone but the most determined professional thief with a little time on his hands. Well built and weighing in at a shade over 6lbs it's a lock to carry occasionally or leave permanently at the place you secure your steed. Used in conjunction with a decent quality cable to secure front wheel etc you'll be pretty confident your bike will stay put.

Maximum security and no worries.

I bought this locker too late, after my previous bike was stolen in front of lidl supermarket. Now I feel more safe locking my new bike with a top locker. Yes, it's masive and heavy, but it's worth every penny when you don't want to lose your bike. I didn't pay for this locker before thinking it 's too expensive, but I lost my old bike 450 pounds, and I spent 500 for a new one. Yes, can be cut but not so easy. Quick free delivery next day.

Nice and Secure D-Lock

Nice D-lock. Very Secure 10/10 18mm width.It gives you a nice feeling of security and you don't have to care a lot about your bike when you lock it for some time for example outside of my gym and I workout for abou 1-2 hours and don't need to stop my workout to check if my bike is still there. It has a nice price thanks to Sigma Sports and nice delivery method. It was the only store where I found this lock to ship it in Greece at this valuablr Price.Cons: A little bit heavy to carry with you and absolutely you need a big backpack ..

Peace of mind

Bought this around a month ago after extensive research. Very happy with my purchase. Extremely thick and secure lock. It is rather heavy so if mobility is a factor then do take this into consideration. Click and collect was quick and easy.

Probably the best of it's type of lock there is...

As far as bicycle locks go, there is nothing that can guarantee your bike will remain secure when left away from home. This is simply due to availability of easy to purchase tools like portable angle grinders, car jacks (for leverage attacks) and of course easy availability of massive bolt croppers from ordinary DIY stores across the land and isn't really reflective of the quality of lock and fitness for purpose these have. Anyone researching the topic of bike security should make You Tube their first port of call as there are many good educational videos that will show you just how long it takes to break any kind of lock you can think about. Some using just the end of a ball point pen and others with a can of compressed air and a small hammer. And so it is likely ... MoreAs far as bicycle locks go, there is nothing that can guarantee your bike will remain secure when left away from home. This is simply due to availability of easy to purchase tools like portable angle grinders, car jacks (for leverage attacks) and of course easy availability of massive bolt croppers from ordinary DIY stores across the land and isn't really reflective of the quality of lock and fitness for purpose these have. Anyone researching the topic of bike security should make You Tube their first port of call as there are many good educational videos that will show you just how long it takes to break any kind of lock you can think about. Some using just the end of a ball point pen and others with a can of compressed air and a small hammer. And so it is likely our view of what a lock should do that needs altering since if these locks got any bigger and heavier none of us would be able to use them.What you're actually ultimately buying, when purchasing a lock, is a sliding scale of time and the added hassle factor for those professional thieves who make a living from taking bikes so they'll hopefully leave your bike alone and - as mean as it sounds - target someone elses bike instead. Every lock type on sale anywhere to date has more than likely been broken in well under 5 minutes in independent testing (if you don't believe me then just a have a quick search on YouTube). Many of these locks have been broken in under 2 minutes and just about all of them in no more than 3 minutes. If that doesn't sound too impressive in terms of securing your bicycle then that fact needs to be taken in consideration with factors such as where you leave your bike and how visible it is to ordinary passersby as it is also to how you use your lock and the accessibility afforded mr-not-so-honest white van driver. Generally any thief is loath to take too long cracking open a lock with standers by and every chance of being apprehended or accosted or interrupted by a chance encounter with the law or anyone standing up to them (probably not recommended).With some locks being breakable in seconds with a simple pair of bolt croppers with little effort it makes sense to make it as difficult as possible for a professional gang to nab your expensive bike. This means using your head and locking your bike properly (ie through the back wheel and frame dropouts/forks) to something immovable rather than just through the top bar of the bike's frame or just through a wheel etc. You'll also want to use a cable through any removable wheels/the saddle etc and lock that too. A shackle type lock, like this, is susceptible to attacks from both angle grinders and to a far lesser degree, car jacks. It isn't bomb proof but does offer pretty much the maximum level of protection being far more resilient to bolt croppers than heavy duty chains or twisted cables.Kryptonite have moved away from using cylindrical keys and anyone using such a lock (common with shackle , U or D type locks such as this from a few years ago) should really consider upgrading their lock to something which uses a different style key. You get 3 keys supplied with this lock and one of them has an LED built in to illuminate the lock's key barrel when you need a light to guide you. The other 2 are just standard car type keys and are not the strongest looking in the world either though they are double sided like car keys and offer higher security against picking and again, there are plenty of interesting videos on Youtube, which demonstrate how easy it can be for those who know how to pick padlocks etc to quickly render your lock so much worthless metal. Again it doesn't take the best of them very long at all. The one worry is these keys do break quite easily and aren't that strong so it's important you record the unique codes for replacement purposes and take care when using them.I chose this lock after quite a bit of research and it's been a very educational experience. I'd have preferred a nice easier to carry twisted cable lock that can go around your waist instead but seeing how easily they were broken with a pair of oversized bolt croppers was just scary. We're talking just 40 seconds or less. I'd consider using a separate high diameter chain lock in conjunction with a quality shackle lock such as this but really, if you've got to go to this kind of level to secure your bike you should be looking at not leaving it around at all or in a very secure place in a building not accessible to the general public at your place of work etc. These are just too bulky to comfortably carry around and this one is far too heavy to want to take with you on a leisurely ride and so doesn't quite fit the 'pop in lock' spec that would be useful for quickly securing your bike whilst you popped into a convenience store to buy a drink etc. For that I would consider the Abus cable types or just a lighter shackle lock with Kryptoflex type cable for the wheels but I wouldn't leave the bike for any length of time. Well, not my new £1500 bike that's for sure. My oily 14 year old mountain bike, now that's a different matter yet I'd still take care to properly lock it up just so I could be reasonably sure it was there when I came back. Do yourself a favour and go search YouTube for advice on bike locks and tips on how to lock your bike up securely. I'm sure, once you've gotten over the initial shock of how easy it is for pro bike thieves to steal your bike, you'll be glad you did.

most secure lock you will find

This lock is awesome 18mm thick and is beefyI have no worries of leaving my cannondale lefty places knowing it will be there when I get backit comes with a £3000 theft guarantee which is free for 1 year or $25 for 5 years which is just over £20 for 5 years cover as long as the lock fails on theft and not what you lock it to.the only thing that will cut this is an angle grinder so most thieves wont attempt to tryit is a heavy lock but I just chuck in my rucksack

solid 18mm U lock !

I bought this one because is 18mm and the price from sigma was very good.Yes, is heavy but you get the best protection from a ulock. (it can be cut only with power tools).It have a plastic /rubber that cover the hard steel so your frame is protected and also the ulock will not rust. You receive 3 keys and one of them have a nice blue light !I give it 4 stars because customer service from kryptonite is really bad ! They answer after 11 days !! Yes , 11!I contact them because I had an error when I want to register for ATPO. (anti theft protection offer). Also the kryptonite website is poor maintained: you can't attach a file when you send a ticket! Amateurs!sorry for my english!