Best Bike U-locks : Top Picks and Reviews

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You’ve invested a lot in your bike, so it makes sense that you want a lock that will protect it. 

You’ve heard that U-locks offer some of the toughest security for your bike, but you don’t know what makes one better than another. 

What size is right for your bike? 

How thick does a U-Lock have to be to prevent theft without being so heavy that it’s a burden to carry?

Don’t worry. You’re on the right page. 

A Quick Glance : Our Favorite U-Locks for Bikes

U-Lock ModelInner DimensionsThicknessWeight
Abus Granit X-Plus 5404.3" x 9.0"13mm3.2 lbs (1.45 kg)
Kryptonite Kryptolok Series 24.0" x 9.0"13mm3.6 lbs (1.6 kg)
OnGuard Pitbull4.5" x 9.0"14mm4.0 lbs (1.8 kg)
Sigtuna 16mm U-Lock4.5" x 9.0"16mm2.5 lbs (1.1 kg)
Kryptonite Messenger Mini+ Plus3.7" x 6.5"11mm2.5 lbs (1.1 kg)
Abus U-Lock 4406.3" x 3.3"12mm2.3 lbs (1.0 kg)
Kryptonite New York Fahgettaboutit6.0 " x 3.3"18mm4.6 lbs (2.0 kg)
Abus Granit Extreme9.6" x 4.4"16mm5.7 lbs (2.6 kg)

On This Page

Bike U-Locks Buying Guide

We’re here to help guide you through the process of selecting a bike lock to meet your needs. 

We’ll walk you through the characteristics you should pay attention to before you commit to buy.

1. Shackle Size

The shackle is the name given to the U-shaped piece of metal that gives this lock its name. 

Shackle size refers to the size of the space within the u-shape of the lock. 

Generally speaking, you want to buy the smallest U-lock that will fit your needs.

Given the fact that U-locks cannot be folded and stowed like other lock types, a smaller lock is easier to store and transport on your bike. A smaller lock also offers greater security. 

Try to find a lock that fits as tightly to your bike’s frame and whatever you’re locking your bike to as snugly as possible. 


A smaller lock offers less clearance for tools that could force the lock open. A larger lock allows thieves space to insert pry bars or even a hydraulic jack to force the lock open.

2. Shackle Thickness

It goes without saying that the thicker the shackle, the stronger the lock. 

Shackle thickness generally ranges from 13mm to 18mm. 

Shackles less than 13mm are vulnerable to a standard pair of bolt cutters. U-locks with shackles in the 13mm to 15mm range aren’t indestructible but can only be cut by the largest bolt cutters. 

The only thing that will defeat a shackle in the 16mm to 18mm range, which includes such locks as the Abus Granit Extreme and Kryptonite’s New York Fahgettaboutit, would be an angle grinder.

3. Overall Weight

Now before you go out and buy the thickest U-lock you can find, also remember that a thicker lock means more metal, which means more weight. 

The thickest U-locks on the market can weigh upwards of 4lbs. 

With this in mind, you need to consider what you’re willing to carry with you and what level of security you need. 

A lighter weight lock, such as Kryptonite’s Messenger Mini+, maybe all you need to secure your bike in a low crime area for an hour or so, whereas the added weight of a tougher lock may be necessary if you’re planning on locking your bike overnight in an unsecured urban area.

4. Security Levels

Abus Bike Lock Security Ratings

U-lock manufacturers such as Abus and Kryptonite offer security ratings for their locks. 

While these ratings can be helpful for determining just how secure the lock you are buying is, they can also be confusing since each manufacturer uses its own rating system. 

Abus, for example, rates their U-locks on a scale of 1 to 15 with 15 being the most secure. 

Kryptonite, on the other hand, uses a 10-point system with 10 being the most secure. Kryptonite actually takes its rating a step further by using a scale that helps you determine the right security rating for you based on location and time. 

A lock on a car rack for a quick stop would require the lowest level of security while a bike locked overnight in an urban area would require maximum security. 

5. Additional Accessories

Abus U-Lock Bike Mount

Unless you only plan on using your bike lock at home or on a bike rack, portability is an important factor to consider when purchasing a bike lock. 

U-locks such as OnGuard’s Pitbull come with mounts that allow you to attach the lock to the frame of the bike. Some u-locks have your accessories and front wheel in mind too. 

Locks such as Sigtuna’s 16mm U-lock include cables that allow you to secure front wheels, helmets, and other valuable accessories.

6. Anti-theft Protection Offer

Kryptonite Anti Theft Protection Offer

Top lock manufacturers such as Kryptonite and On Guard stand behind their products with anti-theft protection offers. 

How does it work?

Kryptonite, for example, will pay you the cost of your bike (or any insurance deductible) for losses that result from any unintended opening or breaking of the lock by force.

Value for Money Bike U-Locks

Abus Granit X-Plus 540

If you want top-notch security for your bike, look no further than the Abus Granit X-Plus 540, Abus’ top-of-the-line U-lock. 

With a security rating of 15, Abus’ highest possible rating, this lock provides some of the best protection you can buy in a U-lock, making the Granit X-Plus an excellent value. 

It features 13mm-thick bars with double-locks and Abus’ XPlus cylinder for excellent tamper protection. All parts are made from tempered steel. 

With inner dimensions of 4.25” x 9”, this U-lock offers a space large enough to secure your bike’s frame to a post but no so large that it is susceptible to pry bars. 

The Abus Granit 540 comes with two keys, including one with an integrated led light.

Kryptonite Kryptolok Series 2

The Kryptonite Kryptolok Series 2 offers versatility with a combination of a U-lock and cable. 

Kryptolok’s 13mm hardened-steel shackle resists cutting and leverage while a disc-style cylinder prevents lock picking. Hardened deadbolts lock both ends of the crossbar. 

All of these security features give this U-lock a moderate security rating, ranking 6 out of 10 on Kryptolok’s security scale. 

It works with Kryptolok’s Flex Frame-U transit system, allowing you to easily attach it to your bike frame for transport. And at just over 3.5lbs, it won’t weigh you down. 

A 4-foot double-loop cable is included to secure accessories and your front wheel. This lock also includes Kryptonite’s anti-theft protection program, which repays you for the value of the bike if the lock fails.

Budget U-Locks

OnGuard Pitbull U-Lock

Sometimes you don’t need a top-of-the-line U-lock to secure your bike. For budget-minded cyclists who only require moderate security, check out OnGuard’s Pitbull U-lock. 

This lock rates an 80 on Onguard’s 100 point security rating scale. It features a 13-mm thick shackle and a 3.5x 7” opening. OnGuard’s patented X4P Quattro Bolt locking mechanism locks the shackle on four sides. 

The lock is mountable to your bike via a multi-position mounting bracket and weighs just over two pounds. Rubber coatings protect your bike’s finish. 

A micro-light key that shoots a white beam is included to help you lock and unlock the bike in the dark. The OnGuard Pitbull is also covered by OnGuard’s protection program up to $2,251.

Sigtuna 16mm U-Lock

With its heavy-duty security and low price point, the U-lock makes for an excellent budget option. 

The Sigtuna U-lock is designed to defend against cutting and pulling with its extra-thick 16mm hardened steel shackle and double-bolt mechanism. It ranks an 8 out of 10 on Sigtuna’s security level scale. 

This lock also includes a 4-foot long double loop steel cable to secure accessories. 

A mounting bracket attaches the lock to your crossbar for transport. Just keep in mind that all that additional steel does make for a heavier lock. It weighs in at just under 4lbs.

Lightweight U-Locks

Kryptonite Messenger Mini+

Need to keep your bike secure but don’t want to haul around a ton of weight? 

Check out Kryptonite’s Messenger Mini+. 

Although this U-lock, which ranks a seven on Kryptonite’s 10 point security scale, features a thinner shackle at 11mm, it still does a good job of resisting hand tools, bolt cutters, and leverage attacks. 

The Kryptonite Messenger Mini+ features internal dimensions of 3.75” x 6.5” with an optional wheel extender that’s 3.25” x 3.75” to secure your front of the back wheel.  

Best of all, at just over 2.5lbs, this lock won’t weigh you down. 

Kryptonite backs this lock with a 1-year theft-protection warranty for up to $2,500. 

Abus U-Mini 440

Abus’ answer to a lightweight U-lock is the sturdy yet diminutive U-Mini 440. 

Despite its relative lightweight at just 980g, this lock still boasts formidable security features with a 14mm steel shackle that resists cutting and double-locking cylinders that discourage lock picking. 

Abus gives the U-Mini 440 a security rating of 11 on its 15-point scale. 

The lock body features a soft-touch plastic coating that won’t scratch your bike’s finish. Although it does not include a mounting bracket for your bike, at just 5.5” wide, the Abus U-Mini 440 can be easily stowed away in a bag. 

Available colors include yellow and red. 

Very Secure U-Locks

Kryptonite New York Fahgettaboutit

Worried about leaving your bike locked outside in New York City overnight? 


Kryptonite’s aptly named New York Fahgettaboutit U-lock offers an 18mm thick shackle, making it virtually impenetrable to cutting and leverage attacks. 

Adding to this locks high level of security is its small interior locking dimensions of 3.25” x 6”. Hardened double-deadbolts secure the shackle to the lock’s housing while a high-security disc-style cylinder resists picking and drilling. 

Needless to say, the Kryptonite New York Fahgettaboutit is the highest level of security Kryptonite has to offer, ranking a 10 on its 10-point security scale. 

Included with this lock are 3 steel keys and one LED key fob. 

Abus Granit Extreme

Need maximum security and don’t mind paying for it? 

Check out Abus’ Granit Extreme 59/180 U-lock. 

Designed to secure motorcycles, the Granit Extreme features a 16mm shackle, making it virtually immune to cutting attacks. 

The lock’s shackle, lock body, and structural parts are made of hardened steel. The extra thick shackle coupled with ABUS’ X-Plus Cylinder gives this lock a rating of 20 on Abus’ 20-point security scale. 

The Abus Granit Extreme works with an adjustable bracket that allows it to be attached to tubes ranging from 12 to 17mm in diameter. 

This lock comes with two keys, including an LED torch key for visibility at night. 

Hisham Mirza

Hisham Mirza

Hisham Mirza is a staff writer at The Geeky Cyclist who has been with us for more than two years. His favorite part of his job is writing about gravel biking, and he’s always looking for new stories to tell our readers.