Kryptonite New York Diamond Review: From Zero to Hero?

I have now tested 5 Kryptonite New York Diamond bike locks and have another 3 waiting to be tested!

Why so many?

Well, the first one that I bought had a fault that allowed me to cut through the base of the shackle using only 1 angle grinder disc in just 13 seconds.

And despite Kryptonite replacing the faulty lock with two non-faulty locks, me buying another one myself, and all three performing exceptionally well in subsequent tests, people continue to message me (and post on Reddit, etc.) with concerns about faulty New York Diamond locks.

Which is understandable: it’s a very expensive lock, the flaw was very serious, and Kryptonite has not provided any public information about the situation. People are rightly concerned about unwittingly spending a lot of money on a lock that’s not fit for purpose.

Rumors swirl about what indicates a faulty lock. That it’s the size of the gap between the shackle and crossbar. Or how far the anti-angle grinder material extends down the tip of the shackle. And people are returning lots of locks on this basis.

So I bought several more locks to test, document my findings, and hopefully come to some solid conclusions.

I haven’t tested them all yet. But from the five locks I have tested, I feel pretty confident in saying the following:

• The first lock was the only faulty lock I have tested
• A big gap between the shackle and the crossbar does not indicate a faulty lock
• The anti-grinder material not extending very far down the tip of the shackle does not indicate a faulty lock
• The only indication of a faulty lock is if there is no anti-grinder material at all at the bottom of the shackle

The Kryptonite New York Diamond is definitely weaker at the base of the shackle (more on this below). But all the anti-angle grinder bike locks are weaker there. And most of them are weaker there than the Kryptonite.

I will, of course, update my reviews as I continue the testing. But as it stands at the moment, I think the fault has been fixed, and the Kryptonite New York Diamond is the most angle grinder-resistant bike lock I have tested yet.

But let’s get into this in more detail…

How secure is the Kryptonite New York Diamond?

Every angle grinder-resistant bike lock is built slightly differently.

The Kryptonite Diamond uses a 16 mm hardened steel shackle with a sparkly “diamond” material (which is presumably some kind of carbon) fused to its surface. This shackle is then encased in a 1 mm thick steel sleeve. And finally, there is a thick rubber coating on top.

The crossbar is also constructed in the same way: under a thin layer of steel there is another layer of steel covered in this synthetic diamond material.

The sparkly shackle is very similar to that of the OnGuard RockSolid. However, the layer of steel that covers the shackle is something peculiar to the Kryptonite New York Diamond: none of the other locks have this, and I’m not entirely sure why it’s there!

By the way: Kryptonite advertise the shackle as being 26 mm thick. But that’s only if you include the thick rubber coating. The shackle is 16 mm. The steel sleeve that surrounds it is 1 mm thick.

When you include the small space between the sleeve and the shackle, it all comes to about 22 mm of protective material. Which is more than enough to prevent this lock from being cropped by bolt cutters of any size.

Angle Grinder Tests

My initial test on the first lock was really encouraging. It took me 13 abrasive discs and 3 minutes 11 seconds of cutting to break through the top of the shackle.

That’s a genuinely impressive result. In fact, only the SkunkLock Carbon has done better in my tests (14 discs).

However, when I attacked the area where the shackle meets the crossbar with a regular abrasive disc, I got through it in just 13 seconds with 1 disc (which was completely undamaged when I finished).

This was because the lock was faulty: the diamond coating didn’t extend all the way to the base of the shackle, so it was completely unprotected from angle grinders at this point (a similar flaw also plagues the Abus Super Extreme 2500).

Kryptonite saw my test and sent me two replacement locks. And when I tested the first one, things were very different…

This time, it took me 25 discs and over 6 minutes of active cutting to break through the base of the shackle.

You can see both tests in the video below:

Obviously, this time, the anti-angle grinder material did extend the full length of the shackle. And now we have a very impressive result at the base too.

In fact, no other lock I’ve tested has performed as well at the base of the shackle.

It’s also important to note that there is very little movement in the shackle when it has been cut once. Which means that a thief would definitely have to cut the shackle twice to steal your bike.

When I published the video with the vastly improved performance, several YouTube commenters suggested that Kryptonite had sent me a “special” version of the lock that was guaranteed to not have the weakness at the base.

Whereas that seemed unlikely to me, it does seem quite possible that there were still faulty locks in circulation, so after a few months I bought a new lock myself from Amazon and tested again.

The result was the same: there was anti-angle grinder material running the entire length of the shackle. After going through 2 or 3 discs on each side, I didn’t bother cutting the whole way through, as I didn’t want to waste another 25 discs!

For me, that seemed proof enough that the fault was fixed.

However, many people were buying locks, deciding that the gap between the shackle and the crossbar was too big or that the anti-grinder material didn’t extend far enough down the tip of the shackle, concluding that their lock was also faulty, and returning them.

And messaging me about it.

So I bought a load more locks from a variety of independent shops and from Amazon. And I started testing again. I haven’t finished yet, but you can see the results so far in the table below and all the photos in this guide.

The numbers show that none of the locks (apart from the first) were faulty, despite some big gaps between the shackles and the crossbars and varying degrees of anti-grinder material coverage at the tips of the shackles.

Indeed, there was no correlation between those gaps or the amount of anti-grinder material and how easy the lock was to cut. 

However, the table does show a wide range of times and discs required to cut the different locks.

I think this is more down to my evolving technique than anything else. And I may have found a way to avoid the anti-grinder material by cutting a thin layer into the crossbar.

I will confirm this in subsequent tests, but even if it’s possible to just use one disc by missing the anti-grinder material, it will still take ages because of the amount of crossbar you have to cut through.

So this is definitely not a fault. These times and numbers compare very favorably to the other anti grinder locks I've tested.

I should also add that (owing to the initial fault), no other anti-angle grinder bike lock has been subjected to the same scrutiny as the Kryptonite New York Diamond. And if I did the same level of testing on the other locks, I would probably find similar weaknesses.

Diamond Discs

I have also tested the Kryptonite New York Diamond against a variety of diamond discs. It took me an incredible 16 minutes to cut through the top of the shackle. Which is far longer than any of the other locks.

And even at the base of the shackle, it took me over 5 minutes to cut it with a diamond disc.

So although a thief wouldn’t need to change discs, the amount of time it takes, the extra noise, and the fact that diamond discs perform much more poorly than abrasive discs against regular locks mean they are not likely to be a popular option with thieves.

The Crossbar

I also attacked the crossbar. It took me 22 minutes and 4 seconds of active cutting with a selection of diamond and abrasive discs to cut it in half!

So there is no way a thief is getting through that!

So how secure is the Kryptonite New York Diamond, really?

Well, the last four locks are undoubtedly the most angle grinder-resistant locks I have tested to date.

An attack at the main part of the shackle might need 26 disc changes to defeat this lock!

Of course, the first lock was the poorest angle grinder-resistant lock I have tested to date.

But the performance of the four locks since then suggests that Kryptonite has sorted out their manufacturing issues and that hopefully there are no duds in circulation now.

And I now feel very confident recommending this lock to those that need the very highest level of angle grinder protection.

Is the Kryptonite New York Diamond easy to carry?

At 2.2 kg (4.92 lb), this is not a light lock. And with internal dimensions of 8” x 3.75” (20.4 cm x 9.5 cm), it’s not small either.

It’s around the same size as the Litelok X3 and just a little bit heavier, weighing about the same as 6 cans of Coke.

So carrying it around could be a bit of a chore.

Thankfully, Kryptonite include their Flexframe-U Bracket when you buy the lock. This frame mount is the same one as you get with all Kryptonite bike locks, and it has a pretty bad reputation.

But I actually quite like it…

It’s easy to install, and as long as I tighten it enough, it always remains stable for me. I do find it works better on the seat tube than the down tube. But while I was riding around, the New York Diamond barely moved in the mount at all.

Clipping the lock in and out of the bracket is really straightforward. Much quicker and easier than with the frame mounts from other brands, which are more fiddly to use. And more fiddly to install too, by the way.

To be honest, I was really surprised at how well the Flexframe-U Bracket worked. I’d always presumed that the heavier Kryptonite bike locks (like the Fahgettaboudit) didn’t come with a frame mount because the locks were just too heavy to properly support.

But the Flexframe-U Bracket copes really well with the New York Diamond Standard.

And apart from being easier to install and use than the frame mounts from other bike locks, unlike most of them it’s included when you buy the lock, rather than being an add-on that costs extra.

Of course, if you don’t have space on your frame, the lock fits easily into most saddlebags or backpacks. So there are options.

Is the Kryptonite New York Diamond easy to use?

With “standard sized u-lock” internal dimensions, the New York Diamond is big enough to accommodate all kinds of locking scenarios and all types of bike, including chunky city bikes and ebikes.

I was able to lock my slim city bike in a number of different ways: through the down tube and front wheel, the seat tube and back wheel, and the seat stays and back wheel.

With bigger bikes, you may need to adjust your locking style somewhat, but you should always be able to find a way to secure it properly.

The build quality of the New York Diamond (like all the Sold Secure Gold and above Kryptonite locks) is really good. It feels like a premium product. The hard rubber shackle cover is thick and tactile. Likewise, the plastic casing that protects the crossbar feel like an integral part of the lock.

This is in contrast to locks like the SkunkLock Carbon and the Squire Stronghold D16 MAX where the plastic casing feels much cheaper and more flimsy, and likely to break and fall off if dropped.

Keys and Mechanism

Kryptonite provide three keys and a key code (in case you want to order extras) with the New York Diamond.

Personally, I prefer the slider keys used by brands like OnGuard. Kryptonite use a disc detainer mechanism, which is theoretically more secure, but given that bike thieves don’t bother picking locks, that’s kind of irrelevant.

The real issue is that if you insert the key only halfway and try to turn it, you can misalign the discs inside the lock. And that can be a pain to fix.

The keyhole has a sliding cover to protect it from water and dirt, which is great. But it does mean an extra step every time you lock or unlock your bike.

Conclusion: Is the Kryptonite New York Diamond worth it?

If you get a good one, then yes, absolutely!

It is the most angle grinder-resistant bike lock I’ve ever tested. The build quality is top-notch. It comes with a usable frame mount. And the price is very competitive (check Amazon price).

It’s been nearly 12 months since I discovered the faulty lock. I’ve tested another 4 locks since then, from various sources, and they have all been fine. And I’ve also seen tests by other people where the lock also performed well at the base.

So by now I feel pretty confident in saying that the fault is fixed and out of distribution, and you will be safe buying the Kryptonite New York Diamond.

It’s also worth noting that the price of this lock varies wildly, so shop around, as there are bargains to be had!

The last one I bought from Amazon was around the same price as the Litelok X1, which is one of the lowest-priced anti-angle grinder locks you can buy and nowhere near as secure as the Kryptonite!

But don't forget: not everyone needs an angle grinder-resistant bike lock. Check out my guide to the best bike locks to find out more!

Alternatives to the Kryptonite New York Diamond

Looking for something smaller?

You can check the price [Amazon] of the Hiplok D1000 or read my full review for more details!

Looking for something cheaper?

It offers enough protection to deter the vast majority of thieves (they would need to change discs at least once to defeat it).

Plus it’s really competitively priced for an anti-grinder bike lock. It’s also lightweight and compact without being small. And it comes with a variety of decent transport options. Read my full review.

Kryptonite New York Diamond Specs

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