The Kryptonite 10/10 or 9/10 security cost around 100-110 euro and the Evolution which is 8/10 security is 50.

Is it worth the double price?

  • 4
    Voted to close as opinion based. Relative worth is only something an individual can decide for themselves
    – Andy P
    Commented Sep 7, 2022 at 10:12
  • Yes if you live in a high crime area, yes if you have insurance that demands such a lock yes if your bike has quite a high value. No if you live in a low crime area, no if you have no insurance, no if it would be cheaper to buy a new bike.
    – Noise
    Commented Sep 7, 2022 at 10:34
  • 2
    This is likely to be closed as either Opinion, or Shopping. Please don't take that personally. Consider what other bikes around you are locked with as a guide for the required level of protection in areas you park
    – Criggie
    Commented Sep 7, 2022 at 12:13
  • I really depends on your use case. Locks used for permanent locking in your house shared bike storage will be different from a lock for multiple hours outside parking in a city and very different from the lock you take for a long biking trip and use it only for very short shopping for water refills and ice cream in some village grocery store. Commented Sep 8, 2022 at 8:38

4 Answers 4


The underlying question is: "what does the better lock provide you?". Locking a bike has two purposes. One is making your bike less desirable to a criminal than the bike next to it, and one is to ensure an insurance claim is not rejected.

If you are insured, latter is relatively easy to resolve: Read you insurance documents and see if the lock you are thinking of purchasing meets their requirements. If the cheaper one is good enough, then you have cover, otherwise it has little value.

The second is very specific to your situation, where do you park the bike, what is the value of the bike, what is the cost and inconvenience to you of loosing your bike, can you afford a replacement. Presuming the more expensive lock is harder to defeat (far from certain), all it does is take more time or better tools from a thief. If they want your bike, you won't stop them, it they want a bike, it might be enough to make a difference.

Some lock manufacturers offer a guarantee that if you loose your bike they will refund some money (usually insurance excess), which is a difference you may want to consider.

The highest security locks are heavy and bulky out of necessity. If the lock is so heavy and bulky you decide not to carry it with you, it offers no security. A smaller lighter lock with a lower paper based security rating, that you carry with you is infinitely more secure.

  • <pedant> a lock carried with you is also useless. Only a lock actually used when the bike is parked is of value </pedant>
    – FreeMan
    Commented Sep 8, 2022 at 18:22

The answer, of course, is "it depends."

It depends entirely on the bike theft methods that are prevalent in your area. If you're seeing cut locks or chains through brute force destructive methods, then go with the "10/10" expensive one. If not then keep reading and decide what's appropriate for your bike and locale.

I used a pair of evo4s for years and years in NYC and never had a real issue. (chain and small U, then larger U for frame-to-front-wheel)

note: I rode a citified bike

  • Nothing on my bike was quick-release
  • All fasteners required mixed-up tooling by design (various hex/torx sizes). Everything was serviceable, but it took four different tools to remove the handlebars, for example.
  • The saddle was secured to the rear triangle w/ a small section of old chain inside of a section of innertube (so it wouldn't damage anything)

These days, the tools and knowledge to pick a disc detainer core lock are pretty accessible; destructive theft techniques have become a slower and riskier option for professional bike theives. With some practice and an affordable tool, Kryptonite disc detainer core locks can be defeated quietly in less than a minute.

The Evo4 is a fine lock, and if you want decent security, add some redundancy with a second lock with a different type of lock cylinder.


Which locks are you comparing exactly?

For example the Evolution LITE Mini-6 U Lock with its 11mm shackle should already provide good protection against most attacks despite “only” having a 7/10 rating. You’d need an angle grinder or a very good bolt cutter to get through it. A big advantage is its comparatively low weight of 730g.

The biggest U-Locks like the New York Lock M18-WL with 18mm shackle can pretty much only be opened with an angle grinder (needing several cutting discs) or plasma torch. They also weigh >2kg and cost a lot of money. With such a lock I’d be more worried about vandalism than theft.

Pretty much all U-Locks with decent key cylinders should provide better protection than most cable locks and many folding locks out there.

  • "With such a lock I’d be more worried about vandalism than theft." Excellent point. I'd venture that many bike thieves would resort to vandalizing if they're thwarted in theft. Those bolt cutters may not make it through the 18mm shackle, but would make child's play of spokes & chains, leaving you unable to ride home.
    – FreeMan
    Commented Sep 8, 2022 at 18:25

Let's consider the ways locks can be opened.

One is lockpicking. All Kryptonite locks contain disc detainer cores that require specialized tools and skills to pick. They aren't as hard to pick as for example Abloy locks, but probably so acceptably hard that this picking is not the main entry method.

Another is shooting at the lock using a ramset gun. They are guns (i.e. firearms) intended to drive nails. Apparently they are widely available in the 'States (due to loose firearm laws) and can defeat locks. The gun will however make a loud sound, so it will attract attention (somebody will think the bike thief just committed a murder).

Third is a battery powered angle grinder. Some cheaper angle grinders have small cutting capacity, e.g. Ryobi R18AG (with 115mm disc) has only 16mm cutting capacity, so for example Kryptonite New York Fahgettaboudit with its 18mm shackle probably can't be defeated by Ryobi R18AG. However, it's not very expensive to purchase a battery powered angle grinder with a larger 125mm disc and a more powerful brushless motor, allowing more cutting capacity.

Many locks these days have a mechanism which doesn't allow rotation of the shackle once it's cut. If this is the case, two cuts are needed to defeat the lock. Or maybe three cuts, since the first cut may be in an inoptimal location where the bike thief thought that both ends of the shackle could be rotated, and then after realizing it can't, two more cuts may be needed. Also, battery powered angle grinders make a loud sound, and having to make two cuts makes the loud sound attract twice as much attention.

Fourth is a small hydraulic jack. It will bend (and eventually break) basically any lock. It's very slow attack type, but the benefit is that it doesn't make a loud sound so the thief may operate for tens of minutes unnoticed, enough to break the lock.

You can make hydraulic jack and angle grinder attacks harder by purchasing as small lock as you can find. If the area inside the shackle is crowded, a hydraulic jack can't be put there. Also in this case it may be harder to do a successful angle grinder attack, because the risk of collateral damage is higher with a more crowded and immobile lock, and bike thiefs don't want collateral damage if they want to sell the bike, so this may be just what protects your bike from theft. What the bike thiefs want is so long lock that they can move the lock, having free area at the end of the shackle, and then cut (once or twice depending on the lock) at the free area with no risk of collateral damage.

My solution is that I always use the smallest possible Kryptonite Evolution Mini lock, and if I want to lock my bike to a solid object where the Evolution Mini isn't large enough, I carry a separate cable the ends of which go to the Evolution Mini. I know there are locks with thicker shackle than the one on the Evolution Mini, but they could have less security if they are not only thicker but also longer. I also know the cable can be cut very easily, but then the bike thief has to move the bike by a van (carrying the bike to the van since it can't be pushed due to the lock immobilizing the rear wheel) and later defeat the U-lock too, giving even more trouble.

  • Hydraulic cutter blades tend to break when cutting thick, hardened shackles. With angle grinders it can take a full minute or more of non-stop grinding and several discs. >11mm of hardened steel is nothing to be trifled with.
    – Michael
    Commented Sep 10, 2022 at 10:39

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