U-locks (also called D-locks) are basically giant padlocks in two separate parts. A rigid U shaped shackle attaches to a straight crossbar forming a closed D shape around whatever you are trying to secure.
First developed in the 1970s by the company that would go on to become Kryptonite, U-locks revolutionized bike security by providing security comparable to hardened chains at a fraction of the weight. Today, U-locks are offered by all the main bike lock brands including OnGuard, Abus and Oxford.
If you’re only going to buy one lock (and really I recommend you buy two), then a U-lock is probably the way to go. They offer the best balance of security, practicality and price.
Chain locks may provide more options when you’re looking for places to lock your bike but they’re very heavy. If you’re not sure, check out my guide to choosing a lock. But remember: cable locks offer very little security. Never buy a cable lock!
OK, so I hope I’ve convinced you to buy a U-lock. But which is the best U-lock for you? There’s a bewildering range of sizes, weights and prices from a slew of different brands. You can compare a load of different U-locks here. But there are a few other things you need to consider before you buy one…
What size do I need?
Size here refers to the space within the U-lock rather than the thickness of the metal. With U-locks, smaller is better. Smaller U-locks are not only lighter and easier to carry, as long as the metal remains a decent thickness, they are also more secure.
This is because the more full a U-lock is (with your bike and the object it is fastened to), the less room there is for a thief to insert tools that could help them break the lock. With weaker U-locks they could insert a length of metal into the space and try and twist the lock off. With stronger U-locks they could insert a hydraulic bottle jack to try and pop the lock open.
So try to choose a U-lock that fits as tightly as possible around your frame, your wheel and whatever you habitually secure your bike to. Of course the disadvantage of a small lock is that you limit the things you can secure your bike to. Lamp posts, thick sign posts and wide railings are a no-no. You might also struggle a bit in busy bike racks. But this is where you need to think about where you lock your bike and whether the increase in security is worth the decrease in choice.
How thick should it be?
Thickness refers to the diameter of the U shaped shackle. Generally, the thicker the metal, the stronger the lock. However, the type of metal is important too and to be strong, they should always be made of hardened steel.
U-locks with diameters of less than 13 mm will be susceptible to attacks by medium sized bolt cutters which some opportunist thieves do use. Better U-locks, with diameters of between 13 and 15 mm are unlikely to be defeated by anything but the biggest bolt cutters which most casual bike thieves just won’t have. However some thieves will, so at the top of the range there are the thickest locks, with diameters of 16 to 18 mm which cannot be cropped by even the biggest bolt cutters.
Of course even the thickest U-locks can be defeated by power tools such as angle grinders, but there is nothing you can do about that. All you can do is buy the strongest lock you can afford and try to limit the opportunities any thief will have to work on it with power tools!
So, the thicker your U-lock, the better. But of course the thicker the metal, the more heavier the lock and this brings us to our next consideration…
How easy is it to carry?
This is a very important consideration because if it’s too difficult to carry around on your bike, then you probably won’t bother. Maybe you’ll start using something smaller and lighter. Or maybe sometimes you won’t use a lock at all. And this is when your bike will get stolen.
With U-locks, portability is affected by the size and weight of the lock and the quality of the frame mount that usually comes with it. The frame mount is normally a plastic bracket that fixes to the frame of your bike, into which the lock clips while you are riding around.
Depending on what type of bike you have (and what other accessories you have attached to your frame), the mount can usually be fixed in a number of different places including the top tube, the seat tube, the down tube or even the seat stays or handlebars.
Unfortunately, lock manufacturers often neglect the design of their frame mounts and many cyclists complain about their quality, especially those that come with the cheaper locks. A good frame mount should fix securely to your frame and hold the lock tightly so it doesn’t move about while you are riding.
However, there are many reports of mounts that are difficult to attach to the bike, not secure against the frame and unable to prevent the lock rattling about or even falling off when the bike is being ridden! So, if you think you will be using a frame mount to transport your lock, try to choose a lock that comes with a good one.
Of course you don’t have to use the frame mount that comes with your lock. You could carry it in a bag. However bear in mind that locks will get wet and dirty and some U-locks are heavy enough to make carrying them on your back very uncomfortable.
You could also put it in your basket or clip it to your luggage rack if you have one. You can even fit the smaller ones in your pocket! And because most of the normal mounts are so poor there are also lots of third party solutions. Holsters that go round your waist. Brackets that attach to your handlebars.
I just thread the shackle of my U-lock through my seat rails and then lock it up in between the seat stay and the seat tube. This keeps it pretty secure and out of the way. Whether you are able to use this method will depend on the type of seat and the size and thickness of your lock. However if your lock is too short to reach the space between the seat stay and the seat tube, you can always use velcro straps to secure it to the seat post.
What’s important, is that you think about how you’re going to carry it before you buy your lock. Because if you can’t find a method that suits you, then the chances are you will stop using the lock altogether.
Will it be your primary or secondary lock?
You will have different requirements of a U-lock depending on whether its going to be your primary (or only) bike lock or a secondary lock. If it’s your primary lock, it is responsible for making sure your frame is not stolen. So unless you’re using the “Sheldon method” of locking your bike (and I recommend you don’t), the lock needs to be big enough to go round your frame, your wheel and whatever you’re securing it to.
If it’s your secondary lock, then usually its responsibility is making sure your other wheel is not stolen. Depending on how you lock your bike, a secondary lock may only need to secure your frame to your wheel, and in this case can be significantly smaller.
Do you really need two locks? Well I talk about this elsewhere, but generally, yes, I think it will significantly reduce the chances of your bike being stolen.
The best U-lock for YOU!
OK, so now you know the sort of things you should consider when choosing a U-lock, lets look at some of your options. I have chosen three of the best U-locks in each of four different categories: the best standard size U-lock, the best mini U-lock, the best budget U-lock and the best secondary U-lock.
Every U-lock I review below is a a great choice in it’s own particular category. Which is the best one for you will depend on your circumstances. You can also compare a long list of the most popular U-locks available today.
The best standard size U-lock
If you live in a high risk area then you need a really good lock. How do you know if it’s a high risk area? Well, if it’s a major city, a tourist center or a college or university campus, then it’s probably a high risk area. But wherever you live, if you ride an expensive bike, then you also need a really good lock. What’s an expensive bike? Well, for me anything above $650 / £400 is expensive.
In such cases, maybe you should look for the best protection you can get. The following locks are the most secure standard sized bicycle U-locks available today. The standard size (roughly 8″ x 4″) means you have lot’s of choice when you’re looking for places to lock your bike. Make sure you check the weight though, they’re pretty heavy…
Three of the best standard size U-Locks
|U-lock||Kryptonite New York Lock Standard||OnGuard Brute STD||Abus Granit X Plus 540|
|Bar thickness:||16 mm||16 mm||13 mm|
|Sold Secure Rating:||Gold||Gold||Gold|
|Reviews:||Coming Soon!||Coming Soon!||Our Review|
The New York Standard is Kryptonites most secure, standard sized bicycle U-lock, boasting a 16 mm shackle with double deadbolt locking. It’s slightly narrower than it’s rivals, which makes it more secure, but also gives you less things to lock it to. It’s also the heaviest of the three recommended locks.
Like all Kryptonites locks it benefits from great after sales care, which in this case includes optional anti-theft protection up to $3000 / £1200. And like all Kryptonite locks it suffers from a poor quality frame mount!
Nevertheless, if you’re looking for the ultimate in protection without sacrificing the number of the places you can lock your bike, the New York Standard could be the best U-lock for you. A full review is coming soon.
The Brute STD is OnGuards most secure, standard sized U-lock and also boasts a 16 mm shackle but ramps up the lock mechanism to give you quadruple deadbolt locking! However, whether this makes it any more secure is debatable.
The real advantage the Brute has over its rivals is in the price. At almost half the price of the New York standard and much less than half the price of the Granit X-Plus 540, it’s an absolute bargain! In fact it’s only $10 / £10 more expensive than it’s budget brother the Bulldog. This is incredible value.
Yes, the after sales service may not be as good as Kryptonite. But if you’re looking for the ultimate in practical protection at a budget price, the Brute STD may be the best U-lock for you. A full review is coming soon.
The Abus Granit X Plus 540 is a bit of an anomaly. The shackle is only 13 mm thick, but because it’s made from a specific type of steel and is square rather than round, it’s strength is equivalent to much thicker shackles. This means that the lock can be lighter without sacrificing security!
So the Granit X Plus 540 has the same Sold Secure Gold rating as it’s two rivals but is much lighter despite being slightly bigger. OK, it’s also much more expensive than it’s rivals. But you get fantastic build quality with all Abus locks.
And if you’re looking for the lightest U-lock without sacrificing either practicality or security, maybe the Granit X Plus 540 is the best U-lock for you. You can read my full review of the Granit X Plus 540 here.
The best mini U-lock
If you’re looking for the highest level of security from a lock that is big enough to fit around a wide range of objects, the New York Standard, the Brute STD and the Granit X-Plus 540 are the best bicycle U-locks available today. But we know that smaller U-locks are more secure because they leave less space for a thief to exploit with tools such as hydraulic jacks. So for ultimate security let’s look at some mini U-locks.
Three of the best mini U-Locks
|U-lock||OnGuard Brute Mini||Abus U-Mini 401 Yellow||New York Fahgettaboudit Mini|
|Bar thickness:||16 mm||14 mm||18 mm|
|Sold Secure Rating:||N/A||Gold||Gold|
|Reviews:||Coming Soon!||Coming Soon!||Our Review|
What it doesn’t have is the same Sold Secure Gold Rating as its bigger brother. In fact Sold Secure doesn’t seem to have rated it at all. I can only assume that this is an oversight, as OnGuard give it the same in house security rating as the standard sized lock.
At 9 cm, it’s the widest of the three mini locks, giving you more options when looking for places to lock your bike. And the price once again is fantastic, costing half as much as both the Abus Mini and the Fahgettaboudit.
So if you’re looking for a small U-lock that offers the highest protection at a reasonable weight, without breaking the bank, this could be the best U-lock for you. A full review is coming soon.
The Abus U-Mini 401 Yellow is the smallest, lightest U-lock with a Sold Secure Gold rating available today. With a width of just 8 cm, it’s the narrowest of the three mini locks. It’s also much lighter, being nearly half the weight of the Fahgettaboudit.
This is clearly because the shackle is much thinner. You may see this lock advertised as having a 16 mm shackle, but in fact it has a 14 mm shackle inside a thick rubber casing.
Ultimately, this makes the 401 Yellow less secure that the other two mini locks and some may argue that it’s more of a secondary lock. While it is theoretically possible that this lock could be cut by the very biggest bolt cutters, I have never heard of this happening and with double bolted locking and a Sold Secure Gold rating I think it deserves a place here.
In fact, if you’re looking for ultimate security with the lightest weight and the smallest size, this could well be the best U-lock for you. A full review will follow shortly.
Be careful with the Abus mini U-locks though, the range is confusing. The Abus U-Mini 401 Yellow is the only one with a Sold Secure Gold rating. The Abus U-Mini 40/130 which is available in both red and yellow and looks identical to the U-Mini 401, is in fact lighter, cheaper and only has a Silver Sold Secure rating. It’s still a great lock at a very reasonable price but it’s not in the top tier of the most secure U-locks.
The New York Fahgettaboudit Mini is the only bicycle U-lock with an 18 mm shackle and is undoubtedly the most secure bicycle lock available today.
It’s only 3 mm wider than the Abus U-Mini 401, so it’s pretty narrow. But at 6 inches in height it’s the longest of the three mini locks. It’s double bolted, is the only bicycle U-lock that gets Kryptonites 10/10 security rating and is eligible for anti-theft protection up to $4500 / £2500.
However, ultimate security comes at a price. At 4.55 lbs (2.06 Kgs), the Fahgettaboudit is much heavier than it’s two rivals. In fact it’s the heaviest lock on this page!
But if you want the very best bicycle security available today then this is without a doubt the best U-lock for you. Read my full review of the Kryptonite Fahgettaboudit Mini U-lock.
With all mini U-locks you need to be very aware of the width and height measurements. These locks are really small. If you have a mountain bike with fat tires you won’t be able to fit these locks round the frame, a wheel and a bike rack. In fact, even if you have a more standard bike, you may sometimes struggle, depending on the rack. If you’re worried about whether these locks are going to be suitable for your day to day life, I’d suggest you draw out their dimensions on a piece of cardboard, cut them out and then try them out for size wherever you habitually lock your bike!
The best budget U-lock
Usually the more expensive a bike lock is, the more secure it will be. So can you really risk a “budget” U-lock? Ideally, you should spend as much as you can possibly afford on your bike lock. But if you can’t afford very much, then there are still cheaper locks that provide adequate protection if you ride a less attractive bike or live in a low theft area. If this is the case, a budget U-lock may be the best U-lock for you.
In fact, since the vast majority of bike thefts are by opportunists with limited tool sets, a good budget U-lock that is resistant to these tools can prevent your bike being stolen in the majority of cases.
The budget U-locks I recommend here are not the cheapest on the market. On Amazon there are U-locks for as little as $5 or £6! Please don’t buy these. Locks such as the Bell Catalyst 200 Pocket Bike U-Lock, the Mongoose Large Bicycle U-lock and the Strong Anti Theft Security Lock from MSC are NOT good quality locks. The mechanisms are cheap, the shackles can easily be broken with bolt cutters or twisted off with crow bars and the Bell and the MSC U-locks even use barrel locks which can be opened with Bic pens!
The three locks I recommend will provide good protection against opportunist thieves. Which one you choose will depend on your own circumstances and priorities.
Three of the best budget U-Locks
|U-lock||Kryptonite Kryptolok Series 2 Standard||OnGuard Bulldog DT||Cocoweb ArmBar|
|Bar thickness:||13 mm||13 mm||14 mm|
|Cable thickness:||1 cm||1 cm||1.19 cm|
|Cable length:||1.21 m||1.20 m||1.52 m|
|Sold Secure Rating:||Silver||Silver||N/A|
|Reviews:||Our Review||Our Review||Our Review|
The Kryptonite Kryptolok Series 2 is the classic U-lock. The 13 mm shackle should defeat all but the biggest bolt cutters. And Sold Secure give it respectable Silver security rating.
It’s well made, dependable and benefits from Kryptonites renowned after sales care which includes optional anti-theft protection up to $1500 or £800, replacement keys, and full refund if your key breaks in the lock. The only downside is the poor quality frame mount.
But if you’re looking for a practical bike lock for low to medium risk areas from a company that offers great customer service, the Kryptolok could well be the best U-lock for you. You can read my full review of the Kryptolok here.
And while it’s also well made and dependable, it’s slightly lighter and cheaper than the Kryptolock. However, OnGuards after sales care is not as good as Kryptonites. And while the frame mount may be better than Kryptonites, it’s still not great.
But it’s such a good value, if you’re looking for robust, practical protection in low to medium risk areas at a discount price, then the Bulldog could well be the best U-lock for you. Read my full review of the Bulldog here.
The Cocoweb ArmBar is the new kid on the budget U-lock block. With a 14 mm shackle, it’s bigger, heavier and may even be stronger than the Kryptolok and the Bulldog.
However we don’t know how strong the steel is. And there is no after sales care at all. If you have any kind of problem, you’re on your own. On the other hand, it does have a very robust frame mount.
Indeed, if you looking for a strong, cheap U-lock with a dependable frame mount and you’re not concerned by the weight, then the ArmBar may be the best U-lock for you. You can read my full review of the ArmBar here.
The best secondary U-lock
Secondary U-locks are normally used to secure your front wheel to your frame. Or if the lock is big enough, your front wheel to your frame and a bike rack. As a secondary lock, it doesn’t need to be as secure as your primary lock. In fact, if you’re going to be carrying two locks around you want the second one to be as small and light as possible which means it will inevitably be less secure.
However, it still needs to offer adequate protection. And if you have a decent secondary lock, you can always use it instead of your primary lock with the Sheldon locking technique if you’re just nipping to the shops or going somewhere relatively safe. So lets have a look at the best secondary locks available today…
Three of the best secondary U-Locks
The Evolution LITE Mini-6 is a relatively new addition to the Kryptonite range. It boasts a 11 mm hardened MAX-Performance steel shackle that has the same strength as the 13 mm shackles of the Evolution Mini-5, Mini-7 and Mini-9.
This means it’s as strong as some 13 mm locks but a fraction of the weight! At 1.65 lb (0.74 kg), the LITE Mini-6 is not quite the lightest of the secondary locks but it is slightly wider than the barely lighter 1.6 lb (0.726 kg) Abus Granit Futura 64 150. And although it’s not double bolted, you do get the famous bent foot design which makes it easier to use, 3 keys (one with LED light) and Kryptonites optional Anti-theft protection up to $2000 / £900.
It’s also very reasonably priced, so if you’re looking for a strong, light, good value secondary lock that could be also used as a primary lock under some circumstances, the Evolution LITE Mini-6 may be the best U-lock for you. A full review is coming soon.
The OnGuard Bulldog Mini 8013 is the biggest and heaviest of the three locks here. But not by much. It features a 13 mm shackle and is 2 cm wider and 1 cm shorter than the Kryptonite and Abus locks. And in fact, the extra width may help you to lock the wheel, the frame and a bike rack, giving you a little extra security.
But as with all OnGuard locks, the best thing about the Bulldog Mini is the price. It’s half the price of the LITE Mini-6 and a fraction of the price of the Futura 64 150. Once again, this is excellent value.
So if you’re looking for the cheapest, secondary lock around, one which could also be used as a primary lock if you’re really careful, then the OnGuard Bulldog Mini 8013 could be the best U-lock for you. A full review will follow shortly.
The 11 mm shackle is double bolted for extra security. And Abus are renowned for making the very hardest steel and the very highest quality locks. However, you won’t get the anti-theft protection you get with Kryptonite and OnGuard. And it’s by far the most expensive of the three locks.
Nevertheless, if your looking for the smallest, lightest U-lock available today, and again one which could be used as a primary lock at a push, then the Abus Granit Futura 64 150 could well be the best U-lock for you. A full review is coming soon.
U-locks are probably the best way to protect your bike in the street, offering the nicest balance between security, price and practicality. But choosing the best U-lock for your bike is difficult. What size and how thick the lock should be depends on where you lock your bike and how long you leave it. How risky is the area? What will you lock your bike to?
The most secure U-locks are small and thick and heavy and relatively expensive. But if you need to lock your bike to big objects, you’ll need a bigger U-lock. And if you ride a low value bike and live in a low theft area, you won’t need a thick, heavy, expensive lock. So the best U-lock for you will depend on your circumstances.
The Kryptonite New York Fahgettaboudit Mini is undoubtedly the most secure U-lock available today. But maybe it’s too small, too heavy or too expensive for your needs.
The Abus Granit X Plus 540 is a better all purpose lock. It’s not as secure as the Fahgettaboudit Mini, but it’s still rated Sold Secure Gold and it’s much bigger, much lighter and comes with a decent frame mount. Read our full Granit X Plus 540 review and let me know what you think.
However both of these locks are expensive. If you’re looking for high security at a budget price, then you should always look to OnGuard…
The Mini Brute is the OnGuard equivalent of the Fahgettaboudit Mini. It’s not quite as thick and it’s not quite as secure but it’s less than half the price! While the OnGuard Brute Standard is comparable to the Granit X-Plus 540. The build quality might not be as good and it’s significantly heavier, but again it’s less than half the price.
But what if you don’t need high security and your main concern is price? Then maybe budget U-lock will do. The Kryptonite Kryptolok Series 2, the OnGuard Bulldog and the Cocoweb ArmBar are all good choices in this case.
However, I would urge caution here. I think you should spend as much as you can possibly afford on a bike lock. Why? Well, firstly because it’s always better to be safe than sorry; you might not think you need a high security lock but a thief may have other ideas! And secondly, while you may not need a high security lock now, what happens if you move areas or upgrade your bike? A good lock, well looked after, can last for many years and many bikes. Maybe it’s better to invest once in a good one than to keep buying new ones every time your circumstances change?
If the locks on this page don’t meet your needs, have a look at this long list of U-locks. You can compare them for weight, size and security rating and hopefully you can find the best U-lock for you.
But whatever your circumstances, I would urge you to never choose a lock with a Sold Secure rating of less than Silver. Or if the lock is not rated by Sold Secure, the same in house security rating as one of their locks that is rated Sold Secure Silver.
I hope this page has helped you to find the best U-lock for your needs. You should also check out our article on wheel and seat security. And don’t forget to make sure you know how to lock your bike properly too! If you have any comments, suggestions or questions, please let me know below…