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D Lock vs Chain Lock – Which Is More Secure?

D locks vs Chain locks, the clash of the Titans. D locks (otherwise known as U locks) are the most popular style of bike lock, but how do they compare to bike chain locks? 

In an ideal world, you’d use one of the best chain locks and one of the best D locks to secure your bike. However, I  understand that not everyone has the budget to afford two top-of-the-range bike locks! 

That being said, I did include several high security, affordable D locks and chain locks in my review of the best cheap bike locks. Have a read!

Both types of locks provide different features and are suitable for different situations. This leaves us with one question: Which is best, D lock vs chain lock?

D lock vs chain lock pros and cons
D locks and chain locks provide a great level of protection for you bike. You'll need to decide which is more suited to your needs.

D lock vs Chain lock is a debate that you can often find on cycling forums.  

Below I’ll break down and compare the differences between D locks and chain locks.

I’ll also recommend some of the best and most affordable locks from either category, as well as several helpful bicycle security tips and tricks!

Table of Contents
    Add a header to begin generating the table of contents

    Overview - D Lock (U Lock) vs Chain Lock

    By reading through this article, you’ll be able to decide which of these locking systems works best for you. 

    If you’re looking for something that’s portable and can be used to secure your bike almost anywhere, then a D lock (U lock) would be the more suitable choice. 

    If however, you are looking for a super-secure lock that will remain in one location (bike shed, garage) you may be better off investing in a top-of-the-range chain lock.

    The table below compares some of the best performing locks from each category (D lock, portable chain, stationary chain). If you’d like to find out more about each type of lock, keep reading! 

    The Best D Locks & Chain Locks

    Preview
    Best D lock
    Best Budget Bike Lock
    Model
    Kryptonite Fahgettaboudit Mini
    Kryptonite Fahgettaboudit Chain 1415
    Hiplok Gold
    OnGuard Brute
    Pros
    • Bolt cutter proof shackle
    • Double deadbolted
    • Best D lock
    • Top quality stationary chain
    • Lifetime warranty
    • Manganese hardened steel
    • Highly portable chain
    • Multiple locking options
    • Wearable design
    • Bolt cutter proof shackle
    • Best budget bike lock
    • Sold Secure Diamond
    Cons
    • Heavier than other D locks
    • No mount supplied
    • More expensive
    • Non portable
    • Thinner chain links
    • Heavier than D locks
    • Heavier than other D locks
    • Low quality mounting system
    Conclusion
    There's no questioning it, the Fahgettaboudit is the best and most secure portable bike lock on the market to date. If there was a more secure D lock, I'd be using it!
    Easily one of the best chains on the market. It's non-portable but can safely secure multiple bikes.
    The Hiplok Gold is one of my favourite portable chain locks. It's easy and comfortable to cycle with and provides multiple locking options. It's not as secure as the Fahgettaboudit D lock though.
    The OnGuard Brute is the best budget bike lock on the market. It's bolt cutter proof and comes with a lifetime guarantee. The choice is easy.
    Shackle Diameter
    18mm
    14mm Chain Links
    10mm
    16.8mm Hardened Steel
    Weight
    4.55 lb (2.06 kg)
    10.8lb (4.9kg)
    4.85lb (2.2kg)
    4.1lb (1.86kg)
    Lock Dimensions
    • Width: 3.25" (8.3cm)
    • Length: 6" (15.3 cm)
      • Length: 3.25’ (100cm)
      • Length: 33.5″ (85cm)
      • Width: 4.53" (11.5 cm)
      • Length: 7.96" (20.2 cm)
      Security Ratings
      • Pedal Cycle Diamond
      • Powered Cycle Gold
      • Pedal Cycle Diamond
      • Powered Cycle Gold
      • Pedal Cycle Diamond
      • Pedal Cycle Diamond
      Best D lock
      Preview
      Model
      Kryptonite Fahgettaboudit Mini
      Pros
      • Bolt cutter proof shackle
      • Double deadbolted
      • Best D lock
      Cons
      • Heavier than other D locks
      • No mount supplied
      Conclusion
      There's no questioning it, the Fahgettaboudit is the best and most secure portable bike lock on the market to date. If there was a more secure D lock, I'd be using it!
      Shackle Diameter
      18mm
      Weight
      4.55 lb (2.06 kg)
      Lock Dimensions
      • Width: 3.25" (8.3cm)
      • Length: 6" (15.3 cm)
        Security Ratings
        • Pedal Cycle Diamond
        • Powered Cycle Gold
        Preview
        Model
        Kryptonite Fahgettaboudit Chain 1415
        Pros
        • Top quality stationary chain
        • Lifetime warranty
        • Manganese hardened steel
        Cons
        • More expensive
        • Non portable
        Conclusion
        Easily one of the best chains on the market. It's non-portable but can safely secure multiple bikes.
        Shackle Diameter
        14mm Chain Links
        Weight
        10.8lb (4.9kg)
        Lock Dimensions
        • Length: 3.25’ (100cm)
        Security Ratings
        • Pedal Cycle Diamond
        • Powered Cycle Gold
        Preview
        Model
        Hiplok Gold
        Pros
        • Highly portable chain
        • Multiple locking options
        • Wearable design
        Cons
        • Thinner chain links
        • Heavier than D locks
        Conclusion
        The Hiplok Gold is one of my favourite portable chain locks. It's easy and comfortable to cycle with and provides multiple locking options. It's not as secure as the Fahgettaboudit D lock though.
        Shackle Diameter
        10mm
        Weight
        4.85lb (2.2kg)
        Lock Dimensions
        • Length: 33.5″ (85cm)
        Security Ratings
        • Pedal Cycle Diamond
        Best Budget Bike Lock
        Preview
        Model
        OnGuard Brute
        Pros
        • Bolt cutter proof shackle
        • Best budget bike lock
        • Sold Secure Diamond
        Cons
        • Heavier than other D locks
        • Low quality mounting system
        Conclusion
        The OnGuard Brute is the best budget bike lock on the market. It's bolt cutter proof and comes with a lifetime guarantee. The choice is easy.
        Shackle Diameter
        16.8mm Hardened Steel
        Weight
        4.1lb (1.86kg)
        Lock Dimensions
        • Width: 4.53" (11.5 cm)
        • Length: 7.96" (20.2 cm)
        Security Ratings
        • Pedal Cycle Diamond

        Last update on 2024-03-13 at 05:50 / Affiliate links / Images from Amazon Product Advertising API

        D lock vs Chain Lock - Which Is the Most Practical?

        D Locks - Practicality

        D locks, as stated above, are normally lightweight and tend to be no longer than 25cm. This means they can easily fit into your rucksack.

        A good quality D lock will normally come with a mount that will enable you to directly attach your lock to your bike’s frame.

        In Backpack Bike Mount

        The shackle of a D lock is one solid U shaped piece of metal. Whilst these strong shackles provide good levels of security for your bike, they also limit you with what you are able to secure your bike to.

        You might struggle to fit your D lock around an object such as a lamppost because its locking shackle simply isn’t wide enough.

        The image below shows how a D lock isn’t as versatile as a folding bike lock. A chain lock offers just as many if not more locking options as a folding bike lock, but is much heavier. 

        If you’re interested in folding locks, read my review of the best folding locks.

        D Lock Chain Lock

        Several top-of-the-range D locks have earned the Gold Sold Secure or Diamond rating, and have super small shackles which makes them more portable.

        Whilst a small shackle isn’t always ideal (as shown above), they do provide increased resistance to twist & hydraulic attacks. 

        Portable Chains - Practicality

        Most Portable chains are at least 23″ long (60cm). Thanks to their length and flexible chain link shackles, you benefit from an increased number of locking possibilities.

        Portable chain locks can normally secure your bike to lampposts, whilst a D lock may struggle in this scenario (as shown above).

        A good quality portable chain will almost always be heavier than a D lock. Unfortunately, this means even portable chain locks aren’t hugely portable.

        The Hiplok Lite Wearable - This chain lock can be worn like a belt which is convenient, but its thinner links provide a lower level of security for your bike.

        It can be hard work transporting a chain lock around, and you may have guessed that they don’t come with a carry mount like the majority of D locks.

        Instead, you are left with the option of coiling the chain lock around your bike’s frame or stowing it away in your rucksack. 

        Even the best chain locks (portable or not) are heavy. Securing these directly to your bike whilst riding can actually damage your bike, so I wouldn’t advise this.

        Damaged Bike Frame the best bike chain lock
        (Click to Enlarge)

        Some chain locks are able to be worn by the user. Many portable locks can be worn around the waist or over the shoulder, which makes them easily accessible, but still not majorly comfy.

        If you have an expensive bike, that you do not want to damage, you may have to stow your portable chain lock away in your rucksack.

        This can be uncomfortable but is definitely one of the most effective ways of transporting a portable chain lock.

        How to carry the OnGuard Mastiff 8019
        When reviewing the OnGuard Mastiff chain, I was able to carry it over my shoulder. It wasn't uncomfortable whilst riding, but I wouldn't advise this for longer journeys.

        Stationary Chains - Practicality

        When it comes to stationary chains, their massive weight is not an issue, because there’s no need to carry them around. Normally stationary chains will also be longer, which gives you more locking space to work with. 

        This also gives you the possibility of securing two or more bikes.

        The video below shows some of the Pragmasis Protector range. These are the biggest and strongest bike chain locks that are available to date. I reviewed several chains from Pragmasis’ Protector range here

        Chain locks work better with ground anchors than D locks do. This is thanks to their greater length and size.

        A larger locking area can be a good advantage when securing your bike at home, as you’ll be able to secure more than one bike at a time.

        Which Is More Practical? - D Lock vs Chain Lock

        D locks in many scenarios will be more practical than a chain lock. The best D locks will have a Sold Secure Gold or Diamond rating, and these can be easily stowed away in a rucksack.

        Whereas a chain lock that offers the same security rating is likely to be substantially heavier and therefore, less suited to everyday use.

        Regardless of the extra locking options that you get with a chain lock, it’s hard to compete with the sleek, compact shape and mounting system of a D lock. 

        D Lock vs Chain Lock - Which Offers the Best Security?

        Both D locks and chain locks have weaknesses that are specific to each type of lock. However, there is one very real threat that affects them both… Bolt cutters.

        For years and years, bolt cutters have been a bike thief’s best friend. Some bolt cutters are tiny and can easily be concealed in a pocket or rucksack, whilst some are hefty and can be up to a metre long!

        The bigger the bolt cutters, the more powerful they are due to the increased leverage. This means many locks are vulnerable to larger bolt cutters.

        That being said, I’ve recently produced a review of the best uncuttable bike locks. Have a read if you no longer want to worry about your bike’s security!

        Skunklock vs bolt cutters
        D locks (U locks) and chains with larger shackles & links are much harder to crop. The Skunklock has a diameter of 22mm and wouldn't fit into the jaws of my 24" bolt cutters!

        As bolt cutters are a common weapon of choice for thieves (particularly the 36″ cutters) we need to know how we can combat them.

        The best thing you can do to stop a thief stealing your bike is to purchase the thickest lock possible. The thicker the lock, the harder it is to cut!

        The video below shows just how tough it is to cut the Pragmasis 16mm Protector chain.

        Bear in mind, this test is being carried out in lab conditions. It would be 100x more difficult to attempt this on outside on the street!

        If you want to completely prevent thieves from stealing your bike with hand-powered bolt cutters, you should only consider locks that are 16mm (or more) thick.

        A top-quality 16mm bike lock made with hardened steel can’t be defeated by hand-powered bolt cutters, simply because it’s too thick!

        The Kryptonite New York Fahgettaboudit Mini D lock (18mm thick) and the Kryptonite New York Legend Chain lock (16mm thick) both have chunky shackles/links. Thieves would not be able to crop either of these with hand tools which is just what we want!

        Otherwise, read about the 5 best uncuttable bike locks for undefeatable bicycle security. 

        Preview
        Kryptonite New York FAHGETTABOUDIT Lock - Yellow, Mini, 23 x 15.2 x 3 cm
        Model
        Kryptonite Fahgettaboudit Mini
        Shackle Thickness
        Shackle Diameter: 18mm
        Shackle Width:
        Shackle Width: 8.3cm (3.25")
        Shackle Height
        Shackle Length: 15.3cm (6")
        Weight
        Weight: 2.06kg (4.55lb)
        Security Ratings
        Preview
        Kryptonite New York FAHGETTABOUDIT Lock - Yellow, Mini, 23 x 15.2 x 3 cm
        Model
        Kryptonite Fahgettaboudit Mini
        Shackle Thickness
        Shackle Diameter: 18mm
        Shackle Width:
        Shackle Width: 8.3cm (3.25")
        Shackle Height
        Shackle Length: 15.3cm (6")
        Weight
        Weight: 2.06kg (4.55lb)
        Security Ratings

        Last update on 2024-03-13 at 05:50 / Affiliate links / Images from Amazon Product Advertising API

        The thicker the shackle/link the heavier the lock. The Fahgettaboudit weighs in at 2.06kg making it one of the heavier D locks on the market but offers insane protection.

        The New York Legend chain also weighs in at 4.31kgs. Which is too heavy to be considered portable.

        One of the best things you can do to prevent your lock from being cropped is to learn how to lock a bike properly.

        Trelock U6 shackle space
        When locking your bike with any lock, make sure you use all of its internal locking area. Any unfilled space can be used by thieves.

        Keep your lock off the ground, fill the locking area and make sure that you secure as many components as possible. 

        The only thing that’s out of your control is how skilled the thief is that’s trying to steal your ride!

        But by using a good quality lock and having good bike security skills, thieves be likely to will move onto an easier target. 

        D Locks - Security 

        D locks have several weaknesses that chain locks aren’t affected by. For example, a poorly secured D lock would be vulnerable to hydraulic attacks.

        A hydraulic attack is where a car jack is inserted into the D lock’s shackle, it is then jacked up until the lock pops open. 

        The image below shows a D Lock shackle that has been subjected to a twist attack.

        I found this whilst out cycling and thought it would be a good example of why you should avoid using flimsy, thin D locks. Someone obviously learnt this the hard way!

        Cheap bike lock

        Thicker shackled D locks and ones that are double bolted, are much more resistant to twist and hydraulic attacks.  

        Twist attacks are where an object such as a crowbar (or even a large piece of wood) is inserted into the middle of the shackle.

        From here the crowbar is twisted until the locking mechanism is under too much pressure and pops open. See the video below for a good demonstration.

        The simple way to avoid thieves utilising these methods is to completely fill the shackle of your D lock.

        The video shows an empty bike lock being broken open. If the lock’s shackle was securing a bike there would be considerably less space for the pry bar to be inserted and manoeuvred inside the shackle. 

        I’m easily able to fill the shackle of my Fahgettaboudit Mini, which eliminates the opportunity of twist & hydraulic attacks.

        Kryptonite Fahgettaboudit Mini Locked Bike
        A filled shackle is a more secure shackle!

        All bike locks are susceptible to angle grinders. However, due to the lack of moving parts/links D locks are easier to cut through with an angle grinder.

        Sold Secure, the lock security testing company have reviewed a wide range of D locks on the market.

        Their tests have shown that many D locks meet the security levels needed to earn the Sold Secure Gold and Diamond rating. When choosing a D lock lookout for the Sold Secure Badges shown below.

        Sold Secure Recently added the Diamond rating to their range of bicycle ratings

        The Gold and Diamond ratings are the two highest ratings in the bicycle security category.

        This shows us that the best D locks are suitable for securing your bike in ‘high-risk areas’.

        Portable Chains - Security

        With their extra length, it can be hard to keep both portable and stationary chains off the ground.

        But make sure you do your best! An interesting method used to defeat chain locks is using cold compressed air or liquid nitrogen. 

        If metal has it’s temperature drastically lowered, it can be shattered with a powerful blow from a hammer. This method requires time for the temperature of the metal to be lowered so that it becomes brittle. 

        The freezing method is less favoured by thieves as more tooling and specialist equipment is required.  

        The end of this video below shows a padlock being submerged in liquid nitrogen in laboratory conditions. The metal padlock is then struck twice with a hammer before being completely broken.

        d lock vs chain lock

        It’s not 100% clear if this is due to the liquid nitrogen, but it’s widely known that metal exposed to sub-zero temperatures becomes more brittle.    

        This risk can be reduced by keeping your chain off of the ground and leaving as little slack as possible.

        The main issue that portable chains face is the size of their links. To be considered portable we would say that chain locks need to weigh no more than 3kg. 3kg is a lot of extra weight to carry around, and this might be pushing it for some people. 

        This ultimately limits portable chain locks to 12mm links or smaller as any larger links would be too heavy to carry.

        Bicycle chains of different sizes Sold Secure Gold

        As explained previously, the thicker the shackle or links, the higher the security. This means portable chains won’t provide the greatest levels of security for your bike, but they make up for it in other areas.

        The shortest 12mm chain locks that we could find was the Kryptonite New York Chain 1210. This weighed in at over 3.9kgs making it nearly twice the weight of the most secure D lock available!

        Even Kryptonite’s 9mm Kryptolok Series 2 995 chain weighs in at 2.5kgs. This is still almost 500g heavier than the top range of D locks! 

        Stationary Chains - Security

        Weight is much less of an issue when it comes to stationary chains. As they do not have to be lugged around, you should aim for the thickest links possible. 16mm chain links are bolt cutter proof. 

        As stated above, the moving links of a chain make it much harder to defeat, even with the use of power tools. Their thicker links and flexible chain, make stationary chains the most secure bike lock choice.

        D Lock vs Chain Lock - Security Summary

        D locks do have several security issues that don’t apply to chain locks and vice versa. However, there are a few simple steps that you can follow to reduce the chances of these issues being a threat. 

        Fill the shackle/chain of your lock as much as you can, and make sure to keep it away from the ground.

        Portable chains do not have the same security issues as D locks. You can reduce the chances of theft whilst using a portable chain by keeping it off the ground.

        However, due to their thinner links, portable bike chains will always be more vulnerable to bolt cutters than a good quality D lock. 

        This means that for security, D locks will be more secure than a portable chain.

        Workers inspect a ships anchor chain
        Some say that size doesn't matter. Wrong. When it comes to cycle security the thicker the links or shackle of the bike lock, the better.

        D Lock vs Chain Lock - Which is the Cheapest?

        When it comes to price, D locks are normally less expensive than chain locks.

        The best bike chain locks normally will come with a small D lock that acts as a padlock to secure both ends of the chain.

        Remember, you get what you pay for. If you buy a cheap unbranded bike lock, you'll be leaving your bike vulnerable!

        On top of this, chain locks require a larger amount of metal, especially the bigger ones. This adds to the cost of chain locks, but don’t let that put you off.

        Several top-quality chains were included in my review of the best cheap bike locks. They are, however, more expensive than your average D lock.

        It’s important to remember that if you want the best protection for your bicycle, it will come at a price.

        Don’t be fooled by cheap cable or combination bike locks. These will not provide any protection for your bike and can be removed with wire cutters in a matter of seconds. 

        Kryptonite 004752 NewYorkLegend NewYorkDisc York Legend 1515 Chain (14,5Mm X 150Cm) with Ny Disc 15Mm Shackle New Locks, 150 cm
        Kryptonite New York Legend 1515
        Link Thickness: 14.5mm
        Weight: 14.7lb (6.6kg)
        Chain Length: 4.9' (150cm)
        Kryptonite 004752 NewYorkLegend NewYorkDisc York Legend 1515 Chain (14,5Mm X 150Cm) with Ny Disc 15Mm Shackle New Locks, 150 cm
        Kryptonite New York Legend 1515
        Link Thickness: 14.5mm
        Weight: 14.7lb (6.6kg)
        Chain Length: 4.9' (150cm)

        Last update on 2024-03-13 at 06:38 / Affiliate links / Images from Amazon Product Advertising API

        D Lock vs Chain Lock - Summary

        If you’re a cyclist that uses their bike to commute into work daily, then your best bet is a good quality D lock. D locks are more secure than portable chains and often have better sold secure ratings.

        Normally D locks cost the same if not less than portable chains. D locks are highly practical and can easily be stored in a rucksack or through a belt loop. The list of benefits goes on. 

        If you want the most secure D Lock, that’s portable, super secure and completely bolt cutter proof, you’ll want to use the same one as I do. The Kryptonite Fahgettaboudit Mini

        Preview
        Kryptonite New York FAHGETTABOUDIT Lock - Yellow, Mini, 23 x 15.2 x 3 cm
        Model
        Kryptonite Fahgettaboudit Mini
        Shackle Thickness
        Shackle Diameter: 18mm
        Shackle Width:
        Shackle Width: 8.3cm (3.25")
        Shackle Height
        Shackle Length: 15.3cm (6")
        Weight
        Weight: 2.06kg (4.55lb)
        Security Ratings
        Preview
        Kryptonite New York FAHGETTABOUDIT Lock - Yellow, Mini, 23 x 15.2 x 3 cm
        Model
        Kryptonite Fahgettaboudit Mini
        Shackle Thickness
        Shackle Diameter: 18mm
        Shackle Width:
        Shackle Width: 8.3cm (3.25")
        Shackle Height
        Shackle Length: 15.3cm (6")
        Weight
        Weight: 2.06kg (4.55lb)
        Security Ratings

        Last update on 2024-03-13 at 05:50 / Affiliate links / Images from Amazon Product Advertising API

        Most of the best D locks also come with mounts that allow you to attach the lock to your bike’s frame. This is a bonus as it means your bike D lock will be available to hand, for quick and easy locking. 

        Chain locks are bulkier and are likely to damage your bike if you wrap them around its frame. Some portable chains, such as the Hiplok Gold can be worn around the waist like a belt. However not all portable chains provide this feature.

        Whilst D locks are a fantastic choice of bike lock, they aren’t suitable for everyone. Some cyclists will require a larger locking area and may require a lock that can secure more than one bicycle. 

        D lock vs folding bike lock, D lock shackle won't fit around lamppost
        Due to it's smaller shackle size, the Kryptonite Fahgettaboudit Mini won't fit around large street lights. It will however, fit around all regular bike stands and smaller posts.

        Some D locks have small shackles that may not fit around larger objects (lampposts, large bike rails, etc), so a portable chain would be better suited in these scenarios.

        Cheap, unbranded bike locks are often made from substandard materials, which won’t provide enough protection for your bike.

        Don’t get caught out using a poor-quality lock. Buying a secure bike lock once is cheaper than having to replace your bike!

        If you’re struggling to decide on which bike lock is best for you, then take a look at my bike lock buying guide.

        By following the simple steps set out, you will find out which bike lock best suits you and your bike.

        If you still can’t decide which bike lock you require, have a browse of the pages below for some super secure bike lock recommendations!

        As always, lock it, or lose it!

        Ciao for now.

        Author of This Post:
        James Grear (Lead Editor)
        James Grear (Lead Editor)

        Understanding how devastating it is to have a bike stolen, I've researched & immersed myself in the world of bicycle security since 2013.

        I then built BikeLockWiki in 2019 to share everything I'd learned with the worldwide cycling community so that cyclists can improve their bike security skills and make informed decisions when purchasing new products and services.

        Learn More about Me & BikeLockWiki here.

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        2 Responses

        1. General advice suggests thieves tend to target EITHER d-locks or chains so securing your bike with both is the best way to go in high risk areas. With that said adding a solid silver rated lightweight 8 or 9 mm portable chain can bring additional security when locking bike in high risk areas. It’s worth purchasing one of either to enable options when judging which to use where too if you are securing with just a single locking device.

          1. You’re definitely not wrong!

            If you have the budget to afford two bike locks, using a chain lock alongside a D lock is a great idea.

            The more metal you put in the way of your bike, the better!

            James

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        About the Editor
        Me and My Bike

        James Grear is a lifelong avid cyclist and the lead editor of BikeLockWiki.

        Having invested over five years into researching bicycle security, all information obtained is shared for free with the online cycling community here on BikeLockWiki.

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