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Oxford Alarm D Max Duo Review | The Best Alarmed D Lock?

7 min read

I got hold of the Oxford Alarm D Max Duo because I’d heard it was a great bike lock and had an ear-piercing alarm.

There aren’t many bike locks on the market that use alarm systems as an added deterrent, so I’ve been looking forward to this Alarm D Max Duo review.

The Oxford Alarm D Max Duo is part of Oxford’s range of alarmed D locks.

This range of D/U Locks is made up of 5 different models, each model has its advantages, and some have slightly different security ratings. I’ll cover these in more detail later in this review.

As bicycles become more high tech and expensive, they become more appealing to thieves. The increasing price of bicycles makes locks with extra security measures (such as alarms) more suited to the bikes of today.

If you’re interested in other bike locks with alarms, check out my comparison of the best bike locks with alarms. Otherwise, keep reading for my in-depth review of the Oxford Alarm Max Duo.

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    *Read This - Quick Update*

    Recently Oxford have released a new version of this lock with several improvements. Instead of the silver rating it once held, the Oxford Alarm-D Pro is now Sold Secure Gold rated.

    I’ve reviewed the new version of this lock, have a read of my review here

    Overview - Alarm D Max Duo Review

    Oxford Alarm-D Max Duo D lock with alarm



    Today’s Best Deals:


    Security Rating – Sold Secure Gold
    Weight – 2.1kg (4.63lb)
    Shackle Dimensions – 17.3 x 32cm (6.8 x 12.6″)
    Shackle Thickness – 14mm Hardened Steel
    Warranty – 2 Years

    The Oxford Alarm D Max Duo is a Sold Secure Silver rated bike lock that offers added security thanks to its deafening 120dB alarm.

    Weighing 2.1kg with its mount and extension cable the Max Duo is slightly heavier than most D Locks. Fortunately, the mount supplied with this alarmed D Lock is one of the best I’ve used and provides a secure and convenient way to transport the Max Duo while cycling.

    The 120dB alarm wasn’t taken into consideration when Sold Secure reviewed this D Lock, which is a shame as I think it dramatically adds to the overall security this lock provides.

    If you’re looking for some extra peace of mind whilst leaving your bike secured, any of the locks from Oxford’s Alarm D range are a great choice.

    If you’d like to view the most competitive price for the alarm-d pro, you can do so here .

    How Secure Is the Oxford Alarm D Max Duo? 

    The Alarm D Max Duo is a Sold Secure Silver rated D Lock. Sold Secure award the Silver rating to locks that provide a compromise between security and cost. It’s worth noting that during Sold Secure testing, the alarm feature of the Max Duo wasn’t taken into account.

    Bike lock’s accessories are not included in Sold Secure’s strict testing procedure.

    Just because lock’s accessories aren’t tested, doesn’t mean that they don’t provide extra security. It would simply be difficult to come up with a test that would give comparable results of every bike lock accessory.

    In my opinion, the Alarm D Max Duo’s ear-piercing 120dB alarm considerably increases the security it provides for your bike.

    Thief scared by bike lock with alarm
    The loud 120dB alarm will startle and deter any thief that tries to remove the Max Duo.

    This alarmed D Lock’s 14mm shackle is single bolted. Single bolted shackles provide a vulnerability for thieves to exploit because they’re only secured on one side. Fortunately, the sensors of the Max Duo’s alarm are highly sensitive to movement.

    Any small movements detected by the alarm system will activate a loud preliminary warning tone. If the disturbance continues, the 120dB alarm will begin to sound.

    single bolted shackle oxford alarm d max duo
    Without an alarm, the Kryptonite Kryptolok Series 2 (right) is vulnerable to twist attacks.

    Out of the best alarmed bike locks the Max Duo’s alarm was definitely the loudest and will scare off thieves with ease. If a determined thief decides to brave it out, the alarm will do an excellent job at attracting the attention of members of the public, which will scupper the attempts of any thief.

    The video below shows an example of how the alarm system responds after detecting a disturbance. It’s a good idea to turn your volume down before watching, this lock in loud.   

    Out of the box, I was very impressed by the quality and feel of this D lock. The Max Duo’s 14mm hardened steel shackle provides impressive resistance to sawing and cutting, while its steel mechanism housing offers significant protection from heavy impact attacks.  

    According to the hearing care centre, 120dB is as loud as an aeroplane taking off. Exposure to 120dB for longer than 30 seconds can be damaging, so in case you were wondering, the Max Duo’s alarm feature is powerful.

    The Max Duo comes with a chunky extension cable, which works well alongside the Max Duo and can be used to prevent chancers from stealing the wheels of your bike. 

    I cover how to use the extension effectively towards the bottom of this review.

    Oxford Alarm D extension cable vs OnGuard extension cable

    How Practical is the Oxford Alarm D Max Duo?

    Weight and Size

    Weighing 2.1kg (including mounting system) the Alarm D Max Duo is slightly heavier than your average D Lock.

    This extra weight is understandable when you consider the increased locking area its 12.6” x 6.8” (32cm x 17.3cm) hardened steel shackle offers and the alarm system hidden inside the lock’s body.

    Oxford Alarm Max Duo in backpack
    My rucksack is small (17.5l) but I had no trouble fitting the Max Duo inside

    While the Max Duo isn’t the most lightweight bike lock, I didn’t have any issues carrying the Max Duo and was able to fit it into my backpack alongside other items.

    I also found the increased locking area helpful as it offered plenty of room to quickly secure my bikes components, and was also able to secure multiple bikes effectively. I cover the best way to use this D Lock towards the end of this review.

    Mounting System

    If only all lock’s mounts were as good as the Max Duo’s. Oxford invested time and effort into producing a top-quality mounting system, and it shows. This mount is made from sturdy, high-quality plastic that’s designed to last.

    Oxford mount vs OnGuard mount
    (Click to englarge)

    The mount supplied with the Max Duo will fit the frame of almost any bike and is secured by two metal hex bolts. You’ll need a hex/Allen key to attach and adjust the mount. Otherwise, everything you need is supplied in the box.

    Rubber padding on the back of the mount prevents any rattling while riding and prevents the mount from scratching the paintwork of your bike.

    To mount the Alarm D, slide the straight end of the shackle through the mounting hole and secure it on the other side. Easy!

    As I’ve already covered, if you’d rather carry the lock in your backpack, you won’t have any issues.

    Quality & Maintenance

    I’m not a fan of plastic when it’s used on bike locks. Even when regularly maintained, plastic parts become worn and damaged more quickly than metal and can eventually cause issues.

    Fortunately, Oxford don’t use any plastic with their Alarm D range (apart from the mount).

    A durable rubber covering coats the shackle and either end of the outer locking mechanism. This stops the lock from scratching your bike and prevents damage from knocks and drops.

    Oxford advise that you should “oil your lock once per week to ensure smooth and reliable operation”. I think this is a bit of an overkill. Some good quality Teflon lubricant and white lithium grease applied every month will keep your lock in good working order.

    I’ve put together a helpful guide which covers bike lock maintenance here, have a read if you want to increase the usable life of your lock.

    A long-life CR2 lithium battery powers the 120dB alarm the Max Duo uses, and will very occasionally need replacing. If you use this alarmed D lock daily, you can expect 3-5 months of power before the battery needs replacing.

    How to replace Oxford Alarm D batteries
    To replace the battery of your Alarm D bike lock follow these instructions

    Replacement CR2 batteries can be purchased at a very reasonable price, opting for rechargeable batteries can be a more sustainable, cost-effective option.

    Weatherproofing protects the electronics inside the Alarm D Max Duo, so this lock won’t suffer from being used in the rain.

    Alarm D Max Duo waterproofing

    Locking Mechanism & Operation

    The Alarm D Max Duo is supplied with three keys. I tested this alarmed bike lock for over two weeks and didn’t have any issues with its locking mechanism.

    It’s a good idea to take note of the key code that’s displayed on the keyring. If you lose the keys supplied, this code will allow replacements to be cut for a small fee using the oxford key replacement service.

    Oxford bike locks key code for replacement key service

    It’s a shame that the Max Duo doesn’t have a keyhole cover like the OnGuard Brute. Keyhole covers prevent unwanted dirt and debris from entering the locking mechanism and lower the amount of time you’ll need to spend cleaning your lock. 

    Oxford Alarm D - How to Operate the Alarm 

    If you don’t want to use the alarm feature while securing your bike, it’s super easy to disable.

    When the key is inserted into the lock and rotated once fully, you’ll hear a single tone. The single tone means the alarm is armed. If you turn the key again in the mechanism you’ll hear a double sounding tone. The double tone indicates that the alarm has been disabled.

    Apart from its alarm feature, the Alarm D Max Duo works like any regular D Lock and is efficient and straightforward to use.

    How Much Does the Alarm D Max Duo Cost?

    Out of the three best alarmed bike locks I reviewed, the Oxford Alarm D Max Duo was the most affordable option.

    This D Lock is sold at a price that is affordable to the majority of cyclists, and for a lock of this quality, I believe it’s a reasonable price.

    For the most up to date, competitive price view the Max Duo on Amazon here

    How to Use the Alarm D Max Duo

    Most Secure Locking Method

    Both wheel and frame of bike secured using oxford alarm max duo

    You should always aim to lock as many of your bike’s components as possible, prioritising the most expensive ones. Your most expensive components will almost always be your wheels and frame.

    If your bike uses quick-release wheels, this method is more achievable, if you have an older bike that uses hexagonal bolts the locking method below will be more straightforward for you.

    Otherwise, simply remove your front wheel and use the Alarm D to secure both of your wheels and your frame at the same time.

    This method filled the shackle almost completely which reduces the Max Duo’s vulnerability to twist attacks. 

    Most Convenient Locking Method

    Oxford alarm d and extension cable used to secure bike

    Whilst cable extensions don’t provide a large amount of security; they’re perfect for short term lock-ups or for securing wheels/accessories.

    The quickest and most convenient way to use the Oxford Alarm D Max Duo is to use the D Lock to secure your back wheel and frame, whilst lassoing the cable extension around your front wheel.

    If your wheelset is valuable, I’d always advise securing both wheels with a solid lock rather than a cable extension.

    Included with The Alarm D Max Duo

    • Oxford Alarm D Max Duo
    • Mounting Bracket
    • Extension Cable
    • Instruction Manual
    Oxford Alarm D Max duo box contents

    How Does the Alarm D Max Duo Compare to Other Bike Locks?


    The Only Bike Lock With the Ability to Fight Back



    The Skunklock is a one-of-a-kind bike lock. It’s the only lock that I’m aware of that can fight back against thieves. This D-Lock doesn’t mess around.

    The Skunklock may look like your standard D Lock, but inside its 22mm shackle is a hollow chamber filled with a pressurised vomit-inducing chemical compound.

    If a thief were to cut 8mm into the hardened steel shackle, the noxious compound would be released into the local vicinity, incapacitating the thief.

    I’ve reviewed the Skunklock in more detail here, it’s features make it one of the most interesting and secure locks on the market to date. 

    ABUS 770A Smart X

    The Best Bike Lock for Defeating Thieves

    ABUS 770A SmartX Alarmed D lock



    ABUS’ 770A Smart X was one of the two other locks included in my review of the best bike locks with alarms. This tech-filled smart lock is the only lock I’ve tried so far that uses keyless operation.

    Your smartphone’s Bluetooth signal the Smart X unlocks when you’re nearby allowing quick, keyless operation. The unlocking distance can be adjusted to your personal preference, and extra users can also be permitted to operate the lock if required via the app.

    During my review period, the Smart X D Lock was a treat to use, and I enjoyed the locking location preview that’s visible on the app.

    If you want to find out more about this top of the range bike lock, read my in-depth ABUS 770a SmartX Review.

    OnGuard Brute

    The Strongest Budget Bike Lock

    Onguard Brute Sold Secure Gold Bike Lock



    Usually, when looking at budget bike locks, you can expect spindly locking shackles that could be cut with a small pair of pliers and locking mechanisms that could be picked by a child.

    This is where the OnGuard Brute breaks the mould. This 16.8mm thick hardened steel, quad bolted D Lock is completely bolt cutter proof and shrugs off all forms of attack. Something you don’t see from many locks retailing at a similar price.

    When I reviewed the best cheap bike locks on the market, the Brute came out top. There are a few downsides to the Brute, its cheap plastic mount isn’t enjoyable to use, and it’s chunky shackle makes it slightly heavier than most D Locks.

    However, when you consider the price that the Brute’s sold at [Amazon], you can easily overlook these small hiccups.

    If you’re looking for a cheap, yet super secure D Lock, this is the one for you. Read my detailed review.

    About Oxford 

    Founded in 1973, Oxford originally sold motorcycle security top boxes out of the boot of a car. Over the next ten years as demand grew for Oxford’s products, so did their team working tirelessly behind the scenes.

    In 1985 Oxford began international sourcing and their product range grew dramatically. They quickly went on to become one of the market leaders in bicycle security with their Sentinel range of locks, which are still sold today!

    Since the 1980’s, Oxford have continued to expand their range of high-quality products and have increased their involvement within the motorcycling and cycling communities.  

    Oxford also support several fantastic charities such as Cycle Smart and the NABB (national association of blood bikes).

    Summary - Oxford Alarm D Max Duo Review

    Reviewing the Oxford Alarm D Max Duo has been very easy. I’m yet to experience a single issue whilst using this lock and was seriously impressed by its usability and its thought through mounting system.

    Its one downside is that it uses a single bolted shackle, which does make it more vulnerable to twist attacks. However, as I covered, the 120dB alarm feature is sensitive and will detect any form of tampering, which should scare thieves off before they attempt anything funny. 

    If you haven’t already, go back and watch the video towards the top of this review. You can hear just how loud the alarm feature is. 

    Oxford Alarm Max Duo review mounted on bike

    If you frequently leave your bike locked in busy public areas and find yourself worrying about its security, the Alarm D Max Duo will provide extra peace of mind for you, whilst you’re away from your bike.

    Thanks to its practical cable extension, the Max Duo can be used to secure the components of your bike quickly and effectively. Whilst cable extensions aren’t ideal for long term lock-ups, it saves you the hassle of regularly removing your front wheel.

    The Alarm D Max Duo is reasonably priced, Sold Secure Silver rated and its 14mm hardened steel shackle makes it resistant to most forms of attack. Amazon offers one of the most competitive prices for this alarmed D Lock.

    View the most competitive price here [Amazon].

    Author of This Post:
    Picture of 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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