The Best U-Lock

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Our Top Pick for 2019: KRYPTONITE New York U-Lock

The sad truth is that bike theft is all too common, and the vast majority of stolen bikes are never recovered. The best thing you can do to protect yourself and your bike from being targeted by thieves is to use a good-quality security accessory, and a u-lock is one of the best kinds available. In this article, we’re going to break down some of the best u-locks in the business, so you can pick the one that’s right for your needs, your expectations, and your budget. You’ll also find a section at the bottom on important things to keep in mind before you start shopping.

Let's Have a Quick Look of Our Top 4 Picks:


#1. KRYPTONITE New York U-Lock

KRYPTONITE New York U-Lock Gold Pick

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Whether you’re locking up a bicycle, motorcycle, or scooter, Kryptonite has a u-lock that’s just right for the job. The Kryptonite New York U-Lock is rated level nine out of ten on Kryptonite’s security scale, and wins our vote for best u-lock. With a thick, hardened-steel shackle and disc-style cylinder, it means business for riders looking for the best.


The New York U-Lock has a double-deadbolt design, so the cylinder locks to the shackle on both ends for extra security. (The cylinder is the part of the lock that contains the keyhole and breaks away from the ‘u’-shaped part to open the lock.) The cylinders of lower-quality u-locks lock on one side only, while hooking and pivoting on the other. The keyhole of the New York is located on the center of the cylinder, and features a small sliding cover to protect the metal parts inside from dust and moisture.

The most secure key-operated u-locks, like Kryptonite’s NY, utilize disc-type cylinders. Disc locks are much more durable than pin locks, and are less likely to jam up after months or years of outdoor use. Disc cylinders are also much more difficult to pick that the less expensive pin-style locks, of the kind typically used in inexpensive, lightweight cable or chain locks. In most cases, the presence of a disc-type key mechanism will lead a thief to attempt to cut the lock instead of picking or prying it open. This brings us to our next section: Shackle thickness.

The NY U-Lock features a beefy 16-millimeter diameter steel shackle. Hitting the magic number ‘16’ means this u-lock is nearly impossible to cut with bolt cutters because the jaws won’t even fit around the shackle. Cutting a chain or u-lock with a 16-millimeter or greater diameter requires a power tool like an angle grinder. This makes locks like Kryptonite’s NY very unappealing to bike thieves, who want to get in and out as quickly and quietly as possible, and know how to identify a lock that’s going to make their task difficult.

Weight, Dimensions

At just under 4.5 pounds, the NY is as heavy as it is tough, so lock transportation should be a consideration before you buy.
Dimensions: 4”x8”

What’s Included

Your purchase includes one LED light key and two standard keys. Be sure to register your keys with Kryptonite ( when you purchase your lock so you can easily get replacement keys sent to you by Kryptonite if the need ever arises.

The included Kryptonite Transit FlexFrame Bracket mount can be used to mount the lock to your bike frame for transport, and is compatible with frame tubes of any shape ranging from 25 to 80 millimeters. The FlexFrame Bracket is a good alternative to carrying the lock in your bag or on your belt, transferring the weight from your body onto the bike. Alternatively, some riders leave their u-locks attached to the bike rack overnight. If you’re commuting to work or school and regularly locking up at the same place, this could be a convenient alternative to lugging around a heavy lock on your bike or in your bag.

The New York U-Lock comes with $3000 of bicycle coverage or $1000 of powersport coverage with Kryptonite’s Anti-Theft Protection plan. In the sad event that your bike is stolen due to lock failure, opening, or breakage, Kryptonite will pay the cost of your bike up to the $3000 or $1000. Upon purchase of your lock, be sure to register your bike and lock for the program at Keep in mind that if your bike is stolen due to lock failure, you’ll need to report the theft to Kryptonite within seven days, and provide the broken lock, a police report filed within 72 hours of the theft, your lock receipt, and some other documents in order to make a claim.

Kryptonite products are backed by a lifetime warranty against damage caused by manufacturer defects.

What They’re Saying About It

Turning to online product reviews, there is no question that the Kryptonite New York is best in its class. Critics and users laud its strength and quality, and hold the reliability of the Kryptonite brand in high esteem. Describing it as “very robust,” the New York earned highest honors--a Gold rating--from Sold Secure, an international third-party security device testing agency.

Some reviewers have noted that the lock has a tendency to twist around in the mount while you are riding. Issues with the mount may be influenced by incorrect or atypical use, as many reviewers contradict these claims.

The Price

Listed at a Manufacturer’s Suggested Retail Price of $102.95, we found that you can buy Kryptonite products like the New York U-Lock at a significant discount from various online retailers, so it’s worth shopping around if price is a concern. The New York is available in only one color, Kryptonite yellow, which signifies the NY has one of the brand’s highest security ratings (orange and black Kryptonite locks have lower security ratings). The standard model has a eight-inch long shackle. A long-shackle ‘LS’ version is also available for the same price, and provides an extra two inches of ‘u’ space to lock up with.

#2. OnGuard Bulldog LS U-Lock

OnGuard Bulldog LS U-Lock

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If you’re on a budget but still want a seriously sturdy u-lock, the OnGuard Bulldog is a standout option. The Bulldog line is OnGuard’s collection of budget-friendly locks, and the Bulldog LS is positioned right around the mid-range of OnGuard’s ranking system, with a security rating of 63 out of 100. Its tough look and quality build should be enough to make would-be thieves move on to lower hanging fruit. If not, the Bulldog will surely put them to work.

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The Bulldog features OnGuard’s X2P double-bolt closure design. X2P technology makes the Bulldog highly resistant to damage from prying, a method that can be used with success on single deadbolt u-locks.

Made with a 13-millimeter steel shackle, the Bulldog may not be as beefy as the Kryptonite New York, but it is a force to be reckoned with, nonetheless. Though it is possible to fit a pair of bolt cutters around the shackle, it won’t be easy to break it. Product testers at were unable to make any significant damage this way, and resorted to using an angle grider. The testers managed to successfully break through the Bulldog with the grinder in 42 seconds; it took 86 seconds to break a Kryptonite New York.

Weight, Dimensions

Less steel means less weight--the Bulldog U-lock weighs in at 2.8 pounds.
Dimensions: 4.53'' x 11.50''

What’s Included

OnGuard includes a generous five keys--one light key and four standard ones--with the Bulldog U-Lock. With four spares there’s little chance you’ll ever be entirely without a key, but you can register your keys at anyway, just in case you ever need a replacement.

The Bulldog also comes with a frame mounting bracket like the one included with the Kryptonite. The Snap Lock Quick Release mount can be used to conveniently carry your lock on your bike. It has been reported to work without issue on narrower road bike frames. For bikes with larger diameter tubes, like cruisers or mountain bikes, talk to your retailer to confirm fitment.

OnGuard includes a theft protection plan with the Bulldog--up to $1501 in coverage for bicycles and up to $501 for the powersport category. Register for the Anti-Theft Protection Plan at within 15 days of purchasing your lock. While you are there, take some time to familiarize yourself with the rules of coverage and requirements for making a claim.

OnGuard locks include a full lifetime warranty against damage caused by manufacturer defects.

What They’re Saying About It

Nearly all long-term product reviews and buyer reviews for the OnGuard Bulldog are positive, citing the locks impressive quality and sturdiness for the price.

As with the Kryptonite New York mounting bracket, some reviewers commented on the Bulldog’s tendency to move around when attached to the bracket. This seems to be an issue experienced by only a small number of riders. Ultimately, some riders will be bothered by the addition of the lock and bracket installation to their bike frame, while others will accept the intrusion in exchange for its practical value.

The Price

The Bulldog LS is listed by OnGuard for $39.95, but is sold by some retailers for about 30 bucks. The LS is the long-shackle version of the standard Bulldog U-Lock, listed at $34.95. At 11.5 inches long, the LS is two inches longer than the standard Bulldog.


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#3. Kryptonite Evolution Series 4 Standard Bicycle U-Lock

Kryptonite Evolution Series 4 Standard Bicycle U-Lock

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Our third place finisher in the race for best u-lock is the Kryptonite Evolution Series 4. Rated an 8 out of 10 on Kryptonite’s security scale, the Series 4 is a hardy, hardened-steel lock featuring a 14-millimeter shackle and double-deadbolt design.


The Evolution Series 4 is the junior to the gold-standard Kryptonite New York. With the same disc-style cylinder and double-bolting construction, these two locks differ in only two areas: Shackle diameter and overall length. At nine-inches long, the Series 4 provides one extra inch of ‘u’ space for locking up compared to the New York. With a 14-millimeter shackle, the Series 4 is made of slightly thinner-gauge steel than the NY, but some of that weight savings is gained back by an extra inch in length. The Series 4 is nine inches long, compared to the NY at eight inches.

Weight, Dimensions

The Evolution Series 4 weighs 3.75 pounds.
Dimensions: 4”x9”

What’s Included

As with the Kryptonite New York U-Lock, described above, the Evolution Series 4 includes one LED key, two standard keys, and the Transit FlexFrame Bracket for transporting the lock on your bike frame.

It includes Kryptonite Anti-Theft Protection of up to $2250 for bicycles and $750 for motorcycles and other powersports vehicles. See the New York U-Lock section, above, for important information about Kryptonite’s theft coverage, or visit

Kryptonite u-locks are covered by a lifetime warranty against manufacturer defects.

What They’re Saying About It

Reviews are overwhelmingly positive for the Kryptonite Evolution Series 4. Comments regarding the mounting bracket persist, but one reviewer suggested disregarding the written instructions included with the lock and instead turning to Kryptonite’s installation video on YouTube for a proper mounting tutorial. As with the Kryptonite New York and OnGuard Bulldog locks, for every review that complains about the mounting bracket, there is another review reminding users to take care to install the bracket correctly.

Weight is another factor reviewers mention as a downside, but with the understanding that the heavy weight is a trade-off for the high-quality build and strength of the lock. Weight will likely be a major consideration when comparing the advantages and disadvantages between the stronger but heavier New York, and the 20% lighter Series 4.

The Price

Listed at $77.95, the Series 4 can be found on sale for around $70.

#4. Mongoose Large Bicycle U-Lock

Mongoose Large Bicycle U-Lock

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*Price typically updated every 24 hours. Current price may be different.

If you live in a low-risk area and are looking for a basic lock to deter the occasional joy rider or neighborhood troublemaker, the Mongoose Large Bicycle U-Lock might be all you need. Available for as little as $10, the Mongoose is a decent lock for a price that can’t be beat.

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If you’ve already invested in one high-quality lock, consider employing the Mongoose as your second level of security--an inexpensive and lightweight rear-wheel or accessory lock. See the section on Pre-Purchase Considerations to read more about why you might consider using two security devices in some situations. But our overall experience shows that lightweight bike locks perform better than normal one. A detailed guide on lightweight bike locks will help you in this case.


The Mongoose features a 12.5-millimeter hardened steel shackle with 8.25 inches of ‘u’ depth and a single-sided locking cylinder.

Weight, Dimensions

The Mongoose u-lock weighs in at 1.5 pounds, so it is light enough to comfortably carry in your backpack. Alternatively, it can be carried on your bike using the included mount.
Dimensions: 5.25” x 8.125”

What’s Included

The Mongoose comes with two keys and a basic clam-shell style mounting bracket that can be tightened down around your bike frame.

What They’re Saying About It

Online reviewers are generally very positive about the Mongoose Large U-Lock, saying it is a functional, satisfactory lock for the price. Some reviewers warn that the locking mechanism is difficult to use and can jam up, but the overwhelming number of users do not report any issues. As with any inexpensive lock, try to keep the key opening as free of dirt, debris, and moisture as possible to extend the life of your purchase.

The Price

The Mongoose u-lock has a Manufacturer’s Suggested Retail Price of $21.99, but can be purchased at major online retailers for just $9.99.

Pre-purchase considerations

Deterrent Factor

No matter how expensive the lock, or how valuable the bike, the presence of a u-lock on your bike will serve as a first line of defence against theft. When you choose a lock, you are investing in the power of deterrence. Any u-lock is better than no lock, and any u-lock is better than a cheap combination chain or cable that can be cut in an instant with a concealable hand tool. As we’ve demonstrated in this list of our top four picks for best u-lock, there’s an option out there that will fit your needs and your budget, so you can take a big step towards preventing theft simply by buying and using your first u-lock.

U-Lock Size

On big factor to consider when choosing your u-lock is size. All the u-locks we’ve listed here are between 4- and 5-inches wide, and range all the way from 8 inches long up to 12 inches. U-locks can also be purchased in shorter sizes and longer sizes. Why are there so many options when it comes to u-lock length? Because people lock up different kinds of bikes, in different ways, to different objects. Before you start shopping, it’s a good idea to get an idea of where and how you’re going to lock up your bike, so you know what kind of ‘u’ length you’ll need. Consider the diameter of your bike frame and the post you’ll be locking up to, and think about whether you want to loop one of your wheels into the u-lock as well.

Your Location

One big factor to consider when determining the right u-lock for you is your location. If you’re locking up in a high-theft area like New York, San Francisco, or Seattle, your needs will differ from someone in a quiet suburb.

Criminals in high-theft areas are sophisticated, efficient, and strategic. They’ve got the tools and skills, so the likelihood that your lock’s looks will be enough to deter the thieves is significantly diminished. In these kinds of areas, spending some serious cash on a lock that is not only going to look daunting to a thief, but will live up to its claims when tested is a worthwhile investment. To get the best possible value from high-dollar locks, keep a copy of your purchase receipt somewhere safe and sign up for the theft-protection coverage and key registration right away.

Conversely, if you live in a neighborhood where bike theft is less common and bike thieves are more likely to be casual criminals than seasoned bike Grinches, a mid-range lock might be just right. In this situation, a lock like the OnGuard Bulldog or Kryptonite Evolution Series 4 will likely make enough of a show of force to deter them from even taking a second look at your ride, and will probably hold off any attempts at forcible entry, too.

Should You Use More Than One Lock?

When you lock up your bike with a u-lock, you’ll want to make sure it encloses the frame of the bicycle. Now you need to think about securing your wheels. Most modern bikes have quick-release wheel hubs, so it is not uncommon for criminals to leave the locked-up frame and take the wheels, and wheels can be very costly parts to replace.

If your u-lock is long enough, you can loop the lock through the rear tire, around the frame, and onto the post or bike rack. Now you still have the front wheel to deal with. If your bike and location warrant locking up both your wheels as well as your frame, consider picking up a cable lock or second u-lock to loop around the frame and one or both of your tires. This secondary device can be lighter weight and more convenient to carry with you than your main u-lock, but sturdy enough to prevent a quick grab-and-go of your wheels.

Conclusion (Wrapping it up)

We’ve listed four of the best u-locks available, each representing different price ranges and security levels, all excelling in their class.

As with all purchases, choosing which lock is best for you will mean determining what factors are most important to you, and what factors you are willing to trade off to achieve your main purpose. If you want the very best money can buy, opt for the Kryptonite New York U-Lock. If you don’t have much money to spare but you need to lock up your ride somehow, the Mongoose U-Lock might be the one for you. Both the OnGuard Bulldog and the Kryptonite Evolution Series 4 are great options that represent a middle-of-the-road approach for riders looking for good theft prevention.

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