Best Bike U Lock in 2021 to Protect Your Bicycle

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If you’re reading, then you obviously love your bike and you value its presence in your life. Perhaps you use it to commute to work or school, or it helps you to enjoy the nature trails in your neighborhood during weekend getaways. To keep your bicycle safe, you need to use the best bike U lock that money can buy so that you don’t have to worry about it being potentially “lifted.”

Unfortunately, bike theft is quite common. Mainly because it’s pretty easy to steal a bike as most people don’t take the necessary measures required to keep their bicycle secure. Paired with the growing demand for used components and bicycles, this creates a real problem that cyclists must be aware of.

To help you find the right one for your needs, we did some research and testing to bring you the following comprehensive guide.

Bike U Lock Reviews

Take your pick among the following options:

1. Kryptonite New York Standard U Lock

The reason why we have the Kryptonite as the first option of the best bike U lock is the fact that this company is so confident about the quality and performance of their product that they’re willing to pay for the replacement of your bicycle for up to $4,000. This is in case it’s stolen while using their product as required.

This is a well-made U-lock that’s constructed from 16mm hardened steel. It has a unique pass-through crossbar design that makes it twice as difficult to twist the lock out of place. After testing it, we can confidently say that this lock can be utilized as a mallet as well.

Also included in the package is a nylon-strap equipped mounting strap. This strap is designed to enable you to attach the lock straight onto the bike frame in many different positions.

Now, the jury is out on the long-term efficacy of this U-lock since the design requires friction in order to keep it attached to the bicycle frame. However, you can always screw the U-lock mount to the bottle bosses for a sturdier, long-term solution.

  • It’s nice and lightweight
  • High security
  • 1-year warranty
  • 16mm steel
  • The mounting bracket is pretty fragile

2. Via Velo Bike U Lock with Cable

Via Velo has outdone themselves with this versatile U-lock for bikes. The steel cable has an impressive length of 6 feet and it comes flexible enough so that it’s easy for you to use in different scenarios.

To further its durability, the cable is coated with PVC. It has a smoke-grey transparent color that protects the lock from rust and scratching. Now, on to the U-lock. In it, you have a sturdy lock cylinder that has the capacity to withstand constant pulling and drilling. This is all without giving in and letting you down.

What makes this worthy to be rated as one of the best bike U locks is the fact that it’s designed precisely to prevent prying and jacking, thanks to the built-in double-bolt crossbar. The keyholes are also covered to keep out dirt and debris build-up while driving.

The package comes with the Via Velo model, a mounting bracket that’s compatible with most bike models, and two keys for your convenience. The mounting bracket itself features an anti-slip pad designed to enable easy cycling.

  • There’s a nice anti-slip pad on the mounting bracket
  • Convenient keyhole cover
  • It comes with a mounting bracket
  • It might come with some of the pieces missing according to customer reviews
  • The cable isn’t long enough to keep both wheels secure

3. ABUS Granit Extreme 59 Key Bicycle U Lock

It’s a well-known fact that German engineering is one of the best in the world. That’s why Abus is among the best bike lock manufacturers on the market, and they’ve been around since the ‘20s.

The reason why this is the best bicycle U lock goes beyond just the brand name though. The company has an impressive product portfolio based on over a century of design and manufacturing experience. Abus is the place to go if you want access to different options. But this review is all about the Granit Extreme 59 which was released in 2019.

What makes this U-lock so impressive is the fact that it’s a heavy piece of artillery that will make a bicycle thief’s life super difficult. It’ll make it impossible for them to steal your bike and that in itself makes its weight worth it.

The best part is that it’s coated with weather sealing. This will help keep it safe from the elements, including rain and snow. You can rest assured that it’ll last for many years to come which guarantees long-term efficacy.

  • Coated with weather sealing for long-term durability
  • Made by one of the best bike U lock manufactures on the market
  • Comes with two keys
  • 16mm shackle
  • It’s very weighty so you can’t even carry it in a backpack
  • Pricey but well worth it

4. Altor SAF Lock

The Altor SAF is the best U lock for bikes because it’s based on an effective angle grinder-proof design. This means it’s extremely difficult to cut through.

In fact, when conducting our own tests, we found that you’d need four grinding discs and six batteries in order to penetrate through this U-lock. And let’s be honest; no bike thief has the patience to go through all that trouble.

What makes this U-lock so effective is the fact that it has a five-inch thick angle grinder. This one is made from the sturdiest materials available, which is hardened steel and aluminum.

But, all of this comes at a cost. This U-lock weighs 13.8 pounds and it’s not light on your pocket either. But, this is a small price to pay for the peace of mind that comes with the guaranteed safety of your bike when using this lock. It’s a great way to keep your bicycle secure when it’s stationary and parked outside of your house or apartment building, for example.

  • It’s next to impossible to cut this lock
  • Angle grinder resistant
  • Double-locking crossbar
  • Made in the US
  • 4 laser-engraved keys
  • It’s really heavy
  • Pricey

5. SIGTUNA Bike Locks

Next we have the SIGTUNA bike lock with a high-security rating of 8 out of 10, bolt-resistant braided cable construction, and an easy to use mounting bracket that’s made with a button which you can use to remove the lock when you need to start getting on the road.

The cable measures 4 feet long and can be utilized to lock in and secure other items apart from your bike. We’re also glad to say that this U-lock is made mainly from 16mm of high-performance steel.

The best part is that you can lock two bikes at the same time with this U-lock thanks to its favorable dimensions of 200 x 105mm.

Also included in the package are two spare keys in addition to the main key. It’s backed by a 60-day money-back guarantee.

  • It comes with three Abloy keys
  • Features a mounting bracket
  • Convenient keyhole cover
  • Backed by a 3-year warranty
  • 60-day money back guarantee
  • You can’t make duplicate keys for the type of keys that this U-lock comes with

6. Kryptonite KryptoLok Series 2 Bicycle U Lock

Here we have yet another offering from Kryptonite. This time a heavy-duty bicycle U-lock with a moderate security rating of only 6 out of 10. At this point, you’re probably wondering why we’ve included it on this list since it has such a low rating. Well, that’s because at the end of the day, it’s still a Kryptonite creation. That brand name alone says a lot about this product.

The KryptoLok as it’s called is pricey but it’s easy to understand why when you consider that it comes with a 13mm hardened steel shackle that’s built to stand against multiple cutting attempts. When you get the package, it’ll come with the U-lock as well as a 4-foot long double loop cable and a rotating disc cover that’s designed to keep the lock safe from the buildup of dust and debris.

Also included in the package are two stainless steel keys that are ergonomically designed for ease of use. You certainly won’t lose any time trying to unlock this from your bike. Once you get the KryptoLok, be sure to get it registered with the Key Safe Program offered by Kryptonite. This is designed to offer customers with an extra set of keys just in case you lose yours.

But you must be able to prove that you’re the owner of the U-lock in the first place, which is why it’s important to sign up as soon as you receive the U-lock.

  • It comes with a mounting bracket
  • Backed by a lifetime warranty
  • Comes with an Anti-Theft protection offer
  • You can register for the Key Safe program
  • It costs a bundle

7. Amazer Heavy Duty Combination Bike U Lock

There aren’t a lot of differences between the Amazer bicycle U-lock compared to the Via Velo and Sigtuna models. But, the few differences that are there actually count and should be mentioned. For instance, all you get is the U-lock and there’s no chain or cable.

This means you have to buy a durable chain when you get this so you can attach it to your bicycle. Also, it comes with a 4-digit combination pad instead of a lock.

Luckily, Amazer had the foresight to cover the combination pad with a protective cover that’ll keep dust and debris from infiltrating it and getting in between the digits. For the most part, this lock is considered more secure than a regular U-lock. This is because it uses a digital combination pad which has been shown to be easy to use, even for children.

The U-lock measures 16mm and is made from PVC coated hardened steel. This means that this is a sturdy U-lock that you can rely on to keep your bicycle safe because it won’t cave under pressure, even the thief uses bolt cutters or a crowbar.

  • Uses a combination pad instead of regular keys
  • So easy to use even for children
  • The combination pad is covered to protect it from dust and debris
  • It doesn’t come with a cable or chain
  • There’s no mounting bracket with this

8. ONGUARD Pitbull U-Lock

A review of the best bike U lock wouldn’t be complete without this ONGUARD Pitbull model. This is a top-range lock that offers great value for money as it’s offered at a very affordable price range.

Its opening has dimensions of 3.5x 7 inches. Based on the Onguard 100-point security rating scale, it has a rating of 80 which is pretty high. The 13-mm thick shackle will make it difficult for any thieves to steal your bike.

It’s coated with rubber to protect it from the elements and OnGuard has backed this U-lock with its protection program to give you further peace of mind.

The best part is that it’s super easy to mount this U-lock using the included multi-position mounting bracket and with a weight of just two pounds, it’s quite compact and portable.

  • The Snap Lock Quick Release bracket allows you to mount this on different parts of the bike
  • It has a high-security rating of 80
  • Ideal for bike messengers
  • Lightweight and compact
  • Comes with a medium-sized shackle
  • There have been some complaints about the locking mechanism getting

How to Get the Best Bike U Lock

Now that you had a chance to go over our bike U lock reviews, read through the following important characteristics that you need to consider as part of your selection process in order to find a good one for your needs, preferences, and budget.


You should definitely pay attention to the materials used to make the U lock and the shackles because this will determine its performance and how long it’ll last.

You want a bike lock that’s made from sturdy materials like hardened steel alloy or titanium. This means that it’ll be close to impossible to penetrate.

Keep in mind that the cheaper the bike lock, the cheaper its materials, and the easier it will be for thieves to pry it open. Thus, defeating the whole purpose of buying it in the first place.

Trust us, buying a bike lock isn’t the time to start scrimping and saving. If your bike means a lot to you then you must be willing to make the investment into its safety.


Based on the previous section you might be tempted to buy the largest U-lock on the market. But, hold your horses because larger locks are usually heavier and can go up to 4 pounds.

You don’t want to carry that kind of weight around, especially if you’re looking for something that you’re going to use on a daily basis.

What you want is something in the middle that offers the best of both worlds. This means that your U-lock should be lightweight yet sturdy.


Shackle size refers to the size of the space that makes up the internal component of the U-shape lock, which is a unique type of lock in and of itself.

For best results, you should opt for the smallest possible U-lock for your specific situation without compromising anything.

Why? Because smaller locks are much easier to transport and they won’t add unnecessary weight to your bike. Keep in mind that you can’t fold a U lock and store it away so it has to be lightweight and portable.

Make sure that the lock you find is designed in a way that allows it to fit snugly against your bike frame.

With all that said, it’s important to note that there are pros and cons to both big and small shackle sizes. For instance, a smaller lock is difficult to pry open because it limits the types of tools that can be used. Whereas thieves can use all manner of tools to open a larger lock.


The thing about locks is that they should ideally have really thick shackles. The general standard is around 13mm to 18mm which is enough for you to wrap it around your bike’s suspension fork.

Anything less than 13mm means that the lock can be easily pried open with a pair of bolt cutters. You’d need some pretty big bolt cutters in order to pry open shackles that measure 13mm to 15mm.

Now, there are even larger U-lock shackles that measure 16mm to 18mm, and can only be defeated by a heavy-duty tool like an angle-grinder. This isn’t something that the average person is carrying around.


As you may have noticed from the previous reviews, some brands offer ratings with their locks, including Kryptonite and Abus.

It’s a matter of pride for a brand to be able to say that their lock has a high rating. While these ratings can provide pointers as to the security offered by the lock, they can also be confusing because they’re based on different rating systems.

For instance, Abus has a rating system that goes from 1 to 15, while Kryptonite uses a 10-point system. However, what makes Kryptonite unique is the fact that their system even takes into account the time and place at which you commonly park your bike. They do this to come up with a more personalized rating.

Types of Bicycle Locks

To thwart thieves in their tracks, bike lock manufacturers have been known to use a wide variety of security mechanisms. Evidence from anecdotal research shows that most lock picking thieves use destructive attacks more often than not.

There are even online masterclasses on how to pick any lock. It’s that advanced and common of a skill, so you want a bike U lock that’s designed to withstand most of the common lock picking methods.

According to a lock picking expert that we interviewed, the following are the most common locking mechanisms and their level of efficacy.

Slider Locks

A slider lock requires that you insert the right key in order to activate a sequence of springless sliders that are contained within a plug, which then corresponds to an external slot. On top of the sliders is a sidebar that must drop down into the slop so that the lock can open.

This can only happen if you insert the right key because that will enable the sliders to get into the right position.

Now, there’s no guarantee that this type of lock will perform the way you want it to, and success is determined by the materials used in their construction.

Disc Detainer Mechanisms

The disc detainer locking mechanism is also referred to as a disc tumbler lock and it’s designed to feature a row of rotating discs that are separated by washers.

There’s a cutout on each disc and these cutouts become zig-zagged when locked. They only align when the right key is inserted and rotated within the mechanism.

Against the discs is a sidebar that only allows for the correct key to unlock the lock. This is what makes it difficult to pick this type of locking mechanism because it requires a very specific type of key to open.

The reason why bike lock manufacturers use disc-detainer mechanisms is because they offer a high level of security and they don’t come with any springs that are easy to penetrate. They’re also usually durable and long-lasting, which is great.

Pin Tumbler Locks

The pin tumbler lock has a cylinder that contains a unique plug with long pin chambers. These pins follow a particular spring-loaded sequence that moves between the plug and housing mechanism.

Usually, the pins will stay in place in between the housing and the plug when the lock is closed so that the plug doesn’t turn spontaneously. With the right key, the pins lift up and go into the plug which is able to turn because of the gap created between it and the housing.

The downside to these locks is that they’re usually easy for experienced lock picks to figure out because they can be raked. Raking refers to the use of a special pick that can be raked in a rapid motion that enables them to turn any lock.

Wafer Bike Locks

Wafer-designed bike locks are as the name implies not as sturdy as one would like.

They have a similar design to a pin-tumbler lock with the main difference being that they mainly utilize spring-loaded wafers that come in a rectangular shape instead of regular pins.

They’re pretty easy to rake and pick when you have the right pick and they can even be opened with something as simple as model keys or jiggers.

Combination Bike Locks vs. Key Bike Locks

Most locks either use a combination lock or a key to secure the lock. Each option has its own pros and cons, as with anything else.

First, you have the combination lock which someone can find out from spying on you while entering the digits. Not only that, but cheaply made combination locks are easy to hack and the worst part is that the pick won’t even need special tools to do it.

Key bike locks are a bit more secure. Just make sure not to lose or misplace your keys or you could find yourself walking home.

Now, aside from the type of bike lock, it’s important to understand that each option can be susceptible to other types of damage and compromise such as rust or environmental contamination. This can cause jamming which makes it difficult for you to use and benefit from the lock.

A lot of the locks we featured on this list are protected by a weather-proof cover on the keyhole. Of course, this doesn’t mean that you should neglect them. You should still lube and clean them regularly and make sure to keep them dry.


This is all you need to know to help you find the best bike U lock that’ll keep your precious bicycle safe from thieves for years to come.

Which bike lock ticks all the boxes for you? If you’re finding it hard to decide, then please allow us to recommend the Kryptonite New York Standard Bicycle U Lock.

We picked this option as the winner not just because of the brand name behind it but also because it’s made to last from durable materials. It has a high rating and is sturdy enough to withstand multiple lock picking attempts without caving in.

So, it certainly won’t let you down no matter what type of environment you’re in.

James Mattis

James is a passionate bicyclist who has done about every kind of biking there is. He loves the wind in his hair, the sun over his shoulder and maybe even the bugs in his teeth. No, just kidding about that last item. He isn’t crazy about road burns, either, but acknowledges that to have the good there is the occasional tumble. James feels that his bike is the place where he can unwind, leave troubles alongside the road, meet new people, go new places, and live the life of adventure that he loves. He is ready to share the ride with you.

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