Best U Locks

Best U Locks: Kryptonite Standard U-Lock

Kryptonite Standard U-Locks are one of the most popular and well known locks. They have been used for years in many different industries such as construction, mining, farming, military and so on.

However, they were not designed with bicycle security in mind.

So what makes them better than other U-locks?

The answer lies in their unique design. Their keyway is made up of three concentric rings which are held together by a central pin. When the lock cylinder is rotated clockwise, it unlocks the outer ring while rotating counterclockwise it opens the inner ring. This design provides maximum resistance against picking attacks and is very difficult to pick even with modern technology.

Another advantage of these locks is that they do not require any tools or special skills to use them. You just need your normal everyday key to open them.

Kryptonite Standard U-Locks are available in several sizes and shapes. Some of the most common ones include:

Small – 8 mm (0.3″) diameter x 6 mm thick (0.19″) thick

Medium – 10 mm (0.35″) diameter x 7 mm thick (0.22″) thick

Large – 12mm (0.5″) diameter x 12mm thick (0.47″) thick

X-Large – 15mm (0.59″) diameter x 16mm thick (0.63″) thick

The larger the lock is, the stronger it is of course. However, larger U-locks are heavier and not as easy to carry around as smaller ones.

You need to find the right balance between strength and portability.

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It is also important to remember that U-locks are only as strong as what you fasten them to. For this reason, it is best to use a U-lock in combination with a steel frame and not just attaching it to a thin basket or carrier.

When using your U-lock, it is a good idea to utilize the shackle mosque so that if someone tries to physically attack you, they will not be able to easily grab onto any part of the lock. The small diameter of these locks also means that even if a thief has access to bolt cutters, they will not be able to get very good leverage on them since their handles are generally shorter and the jaws will have a smaller opening.

However, it is important to note that these locks are among the heavier ones available on the market. This is partly due to their all metal design.

When traveling long distances, you might not want to carry them around as they can become a hindrance rather than a help. There are also some cheaper and lighter alternatives that are just as secure (so long as you don’t lose your key of course).

The main alternatives that you might consider are:

Chain and Disc Lock Alternative:

The chain and disc lock is a relatively lightweight yet strong lock made by OnGuard. It weighs only 1 pound for the pair of them.

While it is less bulky than a U-lock (and cannot be used in as many situations), they can be easily removed by a thief using bolt cutters so it is very important to remember to always be aware of your surroundings.

The chain is 0.1″ thick and the disc lock is 1″ in diameter.

You may also purchase longer chains or disc locks if you want. The standard length seems to be enough for most bicycles. The disc lock uses a key to open and can be rotated by hand once on the bike.

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It is not as secure as a U-lock but it beats having nothing at all (and it’s cheaper too). You can even get bicycle baskets that can hold the chains so they are less of a hassle to carry around.

If you prefer not to use chains, there are also flexi-locks which are flexible cable locks (similar to the ones used on electric scooters) that you may want to look into.

Disc Lock Alternative:

The disc lock is a relatively lightweight and compact lock that can be carried around very easily. Despite their small size, they are quite strong and are difficult to break.

They are only secured by a key and have no numerical combination so if you happen to forget your key… well, you’reout of luck! It is for this reason that you may want to get two locks so that you always have access to one of them.

It is also important to pick a disc lock that is the right size for your frame. If it is too small, a thief can just carry away your bike and if it is too big, they can attack the frame directly (though this would be quite difficult).

Some disc locks are also able to be fastened through your wheel as well for an extra secure hold. This is particularly useful if you are worried about the security of your bike.

U-Lock Alternative:

If you are looking for a lighter and cheaper alternative to the standard U-lock, you may want to look into the folding locks. These locks are slightly different than the U-lock as they can be folded up when not in use.

They work on a similar principle to the disc lock in that they use a key and have no combination.

The main advantage that these have over the disc lock is that they are much lighter so if you are traveling on foot and don’t have a lot of baggage, then one of these could be worth considering.

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The downsides are the same as the disc lock in that it is opened by a key which means if you forget your key… well, you’re out of luck! It is also less compact than the disc lock so may not work for everyone.


Q: I have a chain and disc lock but should I get a U-lock as well?

A: It all depends on how worried you are about the security of your bike. Many people are perfectly happy using just a chain with a disc lock as it is enough to scare most thieves away. U-locks are also a lot bulkier and heavier so some people would rather not hassle with them.

Q: I don’t have a big budget.

Are there any cheaper alternatives?

A: If you are just looking for something to deter thieves from even trying, then standard bike locks like the ones that come with cheap bikes will work. These can easily be bought online or at a local hardware store and if your bike is visible at all, it will be obvious that you have one on it.

If you want something a little stronger, wire cables can be had for very cheap price. These don’t offer as much protection as the chains and U-locks but they will still take some time to cut through and can easily be carried around.

They are also silent so you won’t alarm anyone going around your bike.

Q: I’ve seen people with chains that have hooks on them.

Are those useful for locking to signposts and other things?

A: Yes, those are called anchor links and they are extremely useful for locking your bike in places where there is no fixed item to lock to. All you need to do is loop the chain through the item and then insert the anchor link through the chain. The link will have a open end and a closed end. You lock the open end and voila! An impromptu lock that is much stronger than a cable lock.

Q: I’ve had a chain lock for years and never had a problem.

Why do I need anything else?

A: Much like how a spare tire isn’t needed if you never get a flat, but it’s there just in case you need it. A good D.O.T rated helmet isn’t needed unless you are going at high speed on a regular basis where falls are more likely to happen. The same applies for good security items. If you are just using your bike to get from A to B in your local area, then you may not need the extra security. But if you are going to be leaving your bike somewhere regularly, or you are transporting valuables, then those few extra dollars spent will give you that extra piece of mind.

Q: I’ve seen chainsaws used to cut chains before!

Are they any good?

A: A chainsaw is a serious weapon and requires a lot of energy and force to use it properly. It is also LOUD. Unless you really know what you are doing and have the muscle to pull it off, I wouldn’t advice using one. Not to mention that even the cheapest chain will stop this due to the strong steel that they are made from (usually alloy).

Q: I’ve just had my bike stolen.

What should I do?

A: First of all, you need to report it to the police and check it on the M.I.L.E system. After that, you need to contact your insurance company and make a claim. After this, depending on your insurance policy, you may need to go out and buy a new lock so it is best to do this first before anything else.

As a general rule of thumb, most locks can be broken or bypassed by a skilled criminal in under 5 minutes and most locks can be opened by a theif using household tools in under a minute. So if your bike is going to be left for more than 5 minutes, the best thing to do is just take the wheels with you.

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Be prepared to spend a little extra time doing this if you have an electric bike though.

You must also be prepared to report it to transport authority if it is left on a public transport or in a designated area. Not doing this can result in a fine of up to $200 AUD.

This has happened many times before.

Keep your receipt, lock and any other tools associated with your bike in a safe place at all times. You never know when you may need them again.

While it is always good to have a backup, an incomplete set of tools is almost useless. For this reason, it is a good idea once you have finished using the tool to return it back to the storage container without forgetting about it.

While many tools are easy to carry around in your bag or pocket, some of the larger ones such as the chain breaker are a little too unwieldy to do this with. It is a good idea to have a toolbox or container that you can keep these in.

If you have a lot of bicycles, you may want to consider getting a second toolbox so each one has their own set of tools that they can use. This makes it easier when trying to find the right tool for the job.

If you are going to keep your tools on the bicycle, then you need a way of carrying them around. You can either buy a decent toolbag or make a simple rack and bag to carry them on the frame.

If you go down this route, make sure it doesn’t make the bike top heavy or unwieldy to control.


If you absolutely have to, you can carry a small set of tools in your bag and if you absolutely have no choice but to leave the bike somewhere, you can take the wheels with you and remove the seat and saddle. However, this doesn’t stop someone coming along and stealing the frame as well.

As much as it would be easier to transport your tools in a backpack or messenger bag, I wouldn’t advise this. The problem with toting a set of tools around in a bag is it leaves them exposed and vulnerable to the environment.

This is not an ideal situation as there is always the chance of something getting bent, broken or completely destroyed by accident. This not only renders the tool useless, but now you are without a tool when you may need it.

Another big disadvantage of using a bag to carry your tools around in is you do not have quick and easy access to them. Most bags have to be opened up and searched through in order to find the right tool.

This takes time and depending on what you are trying to fix, this extra time can be detrimental to the task at hand. There have been many a story of a rider being robbed or killed because they took too long to find the right tool for the job.

Another disadvantage of using a bag to carry your tools around in is they can be bulky and heavy when loaded up. Many times, riders will only carry a few essential tools with them.

Sources & references used in this article:

Mounting bracket for U-locks by MS Zane, PL Zane – US Patent 5,127,562, 1992 – Google Patents

Mutable locks: combining the best of spin and sleep locks by R Marotta, D Tiriticco, P Di Sanzo, A Pellegrini… – arXiv preprint arXiv …, 2019 –

Orthodontic traction in a patient with cleidocranial dysplasia: 3 years of follow-up by …, G Floriano, C Derech, GU Ribeiro, A Locks… – American Journal of …, 2014 – Elsevier

… Study of need for thrombolytic therapy and incidence of bacteremia using taurolidine‐citrate‐heparin, taurolidine‐citrate and heparin catheter locks in patients treated … by LR Solomon, JS Cheesbrough, R Bhargava… – Seminars in …, 2012 – Wiley Online Library

Paper board locks by HS Meyers – US Patent 2,821,761, 1958 – Google Patents

Bolted connection for bedstead-corner locks by K Frank – US Patent 1,675,564, 1928 – Google Patents

Adjustable drill guide for door handles and locks by SM Goldstein, FP Collier – US Patent 5,222,845, 1993 – Google Patents

Manufacture of keys for rotary cylinder locks by U Edmond – US Patent 2,677,423, 1954 – Google Patents