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Zefal K-Traz U17 Review | A Reliable All-Round D Lock?

I got hold of the Zefal K-Traz U17 to test and review. I’ve previously reviewed the K-Traz U13 S, and was impressed by its performance, even more so when I realised the price that it sells for.

Throughout this review, I’ll break down the U17’s features and will cover its strengths and weaknesses in detail.

Zefal produce some great quality bike locks at affordable prices. The K-Traz U17 is supposed to be their most secure bike lock, but how practical is it to use and how does it compare to other bike locks?

Find out below in this detailed Zefal K-Traz U17 review.

Zefal K-Traz U17 Review Boxed
Table of Contents
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    Overview - Zefal K-Traz U17 Review



    Today’s Best Deals:


    Security Rating – Sold Secure Gold
    Weight – 1.67kg (3.68lb)
    Shackle Dimensions – 11.5 x 23cm (4.5 x 9.1″)
    Shackle Thickness – 14mm Hardened Steel
    Warranty – 2 Years

    The Zefal K-Traz U17 is a good quality bike lock. It’s sold at a very affordable price and offers features you’d only expect to find on more premium bike locks.

    The U17 uses a quad bolted 14mm high resistance, hardened steel shackle. Whilst it’s not bolt cutter proof, only the largest (non-concealable) cutters would be able to crop this Sold Secure Gold rated D Lock.

    Weighing 3.68lb (1.67kg) the K-Traz is slightly heavier than your standard D Lock, but provides seamless usage thanks to its spring-loaded locking mechanism.

    If you’re looking for a high-security bike lock that’s affordable and can be used in all circumstances, the K-Traz U17 is a great choice.

    It won’t last as long as a more premium bike lock, but with a bit of basic maintenance from time to time, this lock will do you proud.

    Zefal K-Traz U17 Specs
    Weight: 3.68lb (1.67kg)
    Shackle Width: 4.5” (11.5cm)
    Shackle Height: 9.1” (23cm)
    Shackle Diameter & Material: 14mm Hardened Steel
    Security Ratings: Sold Secure Gold

    How Secure is the Zefal K-Traz U17?

    Zefal K-Traz U17 – Security Ratings?

    Zefal gave the U17 17/20 on their in house security rating system, which currently makes it their most secure lock. The U17 is also Zefal’s only bike lock to bear the Sold Secure Gold rating, which is an impressive achievement for such a cheap lock.

    If you’re not familiar with bicycle security ratings, have a read about the different ratings here. Otherwise, put briefly, Sold Secure Gold rated locks are suitable for use in medium/high risk areas.

    Whilst Sold Secure Gold is one of the best ratings a bike lock can achieve, locks within this category have different features and offer different levels of security.

    This means it’s important that you do your research and find a lock that will work well for you and your bike.

    Quality of Materials

    The Zefal K-Traz U17 isn’t the most premium, polished bike lock on the market, this isn’t a surprise when you consider the price the U17 retails at. 

    This budget-friendly D Lock uses a 14mm high resistance steel shackle, which resists most forms of attack.

    Whilst a 14mm shackle isn’t thick enough to be considered bolt cutter proof, a thief that tries to cut through the U17 will not have an easy time!

    Zefal implemented several impressive measures to increase the security of the K-Traz U17, I’ll cover these later in the review.

    I was unaware of how you're supposed to open the U17 and damaged it when opening the outer plastic housing. The metal casing and end caps sit just underneath the outer shell.

    As with most affordably priced bike locks, the K-Traz U17 does use plastic which covers the locking mechanism.

    I attempted to remove the outer plastic shell to have a closer look at the inner mechanism but managed to damage the plastic slightly.

    Obviously, there would be no reason for you to open the lock-up (you’d probably void your warranty by doing so) so this isn’t anything to worry about!

    However, the plastic the U17 uses isn’t the most durable and will begin to show signs of wear and tear faster than a more premium lock would.

    The use of plastic doesn’t present any security issues as the inner locking housing is made from high strength steel with reinforced metal end caps.

    As long as you’re not rough when using the U17, you won’t have any issues.

    Additional Security Features

    The Zefal K-Traz U17 is similar to the OnGuard Pitbull in many ways. Both of these locks use a quad bolted shackle, which increases their resistance to prying and twisting attacks.

    OnGuard Pitbull vs Zefal K-Traz U17
    (Click to enlarge)

    Because the shackle is bolted in two points on either side, two cuts would have to be made through the U17’s shackle before it could be removed from your bike.

    Whilst quad bolted shackles aren’t very common, the OnGuard Pitbull was recently awarded the Sold Secure Diamond Bicycle rating.

    This shows quad bolted shackles can be just as effective at preventing theft as a regular double bolted shackle.

    How Practical is the Zefal K-Traz U17?

    Weight and Size

    Weighing 3.68lb (1.67kg) the K-Traz U17 is slightly heavier than your average D Lock. It really doesn’t feel heavy to use and I was surprised when I weighed it.

    The OnGuard Pitbull weighs 3.55lb (1.61kg) making it slightly lighter than the U17, however, the difference is unnoticeable.

    Zefal K-Traz U17 vs OnGuard Pitbull
    The U17 is less bulky than the Pitbull, but weighs slightly more and doesn't look as intimidating (click to enlarge)

    Locking area is always something you should pay attention to when purchasing a new bike lock. I’d advise opting for a lock that offers enough room to secure your rear wheel and frame.

    These are normally your bike’s most expensive components, so it’s best to prioritise these.

    The U17’s shackle measures 4.5” x 9.1” (11.5cm x 23cm) which is a similar size to most standard D Locks.

    I was easily able to secure both of my wheels and the frame of my bike at the same time, so you shouldn’t struggle when locking your bike with the U17.

    Zefal K-Traz U17 in backpack
    The U17 fit into my backpack alongside other items, without taking up much room

    Thanks to its standard weight and size, I didn’t have any issues fitting the U17 into my backpack and it was comfortable to ride with.

    Shortly, I’ll cover the most effective ways to use the U17, make sure to have a read if you’re considering this high security, affordable D Lock.

    Mounting System

    It’s no surprise that cost has been cut with the mounting system supplied with the Zefal K-Traz U17. For a lock that retails at such an affordable price [Amazon link], you can’t really expect top-quality accessories.

    The quick-release mounting system is made from plastic and it doesn’t feel hugely robust.

    It’s the same mounting system that’s supplied with the OnGuard D Lock range so I knew what to expect before attempting to use it.

    Zefal and onguard bike lock mounts
    Zefal and OnGuard use exactly the same mounting system for their D Locks, they're made from cheap plastic and keep the overall cost of the lock down

    It’s a bit of fiddle to attach the mount, you’ll also need a crosshead (Phillips) screwdriver to attach it using the screws provided.

    The mount only works with round frames which have a 20-42mm diameter, this was an issue for my thick-framed road bike.

    Once attached, the U17’s mount is operated using a spring-loaded plastic button, which is stiff to use at first but loosens up over time.

    Zefal Mount Doesn't Fit Bike Frame

    As I’ve already covered you won’t struggle to fit the U17 into your backpack. If riding with a backpack isn’t for you, there are many good quality D Lock mounts available.

    I’m a big fan of the Oopsmark D Lock Mount, it’s made from leather and is slightly upmarket, but will outlast the cheap plastic mount supplied with the U17.

    Locking Mechanism & Operation

    One of the U17’s strong points is its locking mechanism. I had a few issues with the very similar OnGuard Pitbull, so was expecting a repeat when testing the U17.

    To my surprise, the U17 is smooth to operate and its mechanism is spring-loaded which decreases the amount of fiddling needed to secure your bike.

    Zefal K-Traz U17 Keys
    The K-Traz U17 isn't supplied with an LED key like the OnGuard Pitbull

    The lock is operated by three sidewinder keys which are cut by laser and are therefore more difficult to make copies of without professional assistance.

    Sidewinder keys are also slightly more durable than your average key.

    If you lose the keys supplied with the Zefal K-Traz U17, you’ll be able to get replacements cut as long as you made note of the key code attached to the keys.

    When I buy a new bike lock I always make a note of the code on my phone, so that I can easily order replacements if they’re required.

    How To Maintain The Zefal K-Traz U17

    As with all bike locks, some basic maintenance is required in order to keep the Zefal K-Traz U17 functioning properly.

    I’ve put together a guide that will greatly increase the usable life of your bike lock, you can learn more here.

    Zefal K-Traz U17 automatic keyhole cover
    (Click to enlarge)

    The K-Traz U17’s outer plastic housing does help to keep the inner mechanism dry, and the automatic keyhole prevents foreign particles from entering its keyhole.

    However, cheaper locks are more likely to corrode over time, so I’d advise you to read this guide and keep your lock lubricated.

    The shackle of the U17 is coated in soft rubber, this will prevent the lock from damaging the paintwork of your bike, but will also keep the strengthened metal shackle dry when the lock is exposed to the elements.

    Is the U17 Worth The Money?

    When you consider that the Zefal K-Traz U17 is Sold Secure Gold rated, quad bolted and has a solid 14mm shackle, its price seems extremely cheap.

    Whilst some aspects of the U17 aren’t ideal (mount & plastic casing), for the price you pay [Amazon link], these small downsides can be easily overlooked.

    If you’re looking for a budget-friendly D Lock that provides a good level of security for your bike, it’s worth considering this lock. It’s also worth reading my review of the best cheap bike locks.

    The OnGuard Pitbull retails for a similar price and is worth checking out before deciding which lock works best for you. 

    You can view the most up to date and competitive price for the U17 on Amazon here

    Zefal K-Traz U17 - Best Bits
    • 14mm hardened steel shackle
    • Quad bolted locking mechanism
    • Sold Secure Gold rated
    • Includes extension cable 
    • Two-year warranty
    • Key replacement scheme
    • Anti-scratch rubber coating
    Zefal K-Traz U17 Review Boxed

    How to Lock Your Bike with the Zefal K-Traz U17

    When securing your bike, you should always attempt to secure as many of your bike’s components as possible. The methods below are the best ways to use the U17.

    If you’d like to increase your bicycle security skills, have a read of my guide on how to lock your bike properly.

    If you have quick-release wheels, never leave them unlocked.

    The Most Secure Way to Use the U17

    How to lock your bike with the Zefal K-Traz U17

    Whenever you lock your bike, you should prioritise the most expensive components. This will almost always be both of your wheels and your bike’s frame.

    By securing the most expensive parts of your bike, thieves will most likely move onto an easier target.

    For this locking method, remove your front wheel and use the K-Traz U17 to secure the wheels and frame of your bike, as seen below.

    Removing your front wheel is quite a faff, especially if you don’t have quick-release wheels.

    If you don’t want to remove your front wheel, check out the method below or give a product like Hexlox a try.

    The Easiest Way to Use the U17

    Zefal K-Traz U-17 Extension

    Using a cable extension alongside the U17 allows you to lock your bike’s most expensive components without having to fiddle around with them.

    Simply lasso the cable extension through your front wheel, and pull the free end through bringing it towards your back wheel.

    From here, use the U17 to secure your back wheel and frame and insert the cable onto the shackle before locking.

    Whilst cable extensions provide a minimal level of security, they’ll prevent opportunist thieves from quickly pinching your front wheel.

    Included in the box

    • Zefal K-Traz U17
    • Zefal Cable Extension
    • 3 x Sidewinder Keys
    • Mounting system
    • Mounting Instructions


    Zefal K-Traz U17 Warranty?

    Zefal offer a two-year warranty on all of their products. If a product you purchase becomes defective within this time frame, Zefal will be happy to exchange it for the same product or a similar product if the original is no longer in production.

    A fairly standard warranty that you see from most manufacturers nowadays.  

    How Does The Zefal K-Traz U17 Compare With Other Bike Locks?

    OnGuard Brute 8001

    A More Secure, Sold Secure Diamond Rated Budget Bike Lock

    Onguard Brute Sold Secure Gold Bike Lock



    The OnGuard Brute is a budget bike lock that means business. This impressive D Lock has a 16.8mm shackle which is impossible to crop with bolt cutters.

    It uses a similar quad locking system to the U17 which makes it resistant to even the most brutal attacks.

    When I reviewed the brute, I was impressed with its performance. It’s slightly bulkier than the U17 but for the bolt cutter proof shackle and peace of mind this lock provides, it could be a worthy upgrade.

    The Brute retails at a similar price [Amazon] and most of its features are almost identical to the U17’s.

    Read my review of the OnGuard Brute if security is your priority.

    Kryptonite Kryptolok Mini-7 with Flex

    A Better Quality, Sold Secure Gold Mini D Lock




    Kryptonite never use much plastic within the design of their locks and this is evident when handling the U17 and the Kryptolok Mini-7 at the same time. 

    The Mini-7 has a sturdy weight to it, whereas the U17 uses a fair amount of plastic within its outer shell, which gives it a light, cheaper feel.

    If you have the budget to cover it, the Kryptolok is a great upgrade from the Zefal U17, it’s marginally more expensive, but provides a better all-round experience and its higher quality materials will last you longer.

    It’s no surprise that the Mini-7 was included in my list of the best cheap bike locks

    Foldylock Compact

    A Better Quality, Sold Secure Gold Mini D Lock

    Foldylock Compact Sold Secure Silver Folding Bike Lock



    The Foldylock Compact is one of my favourite bike locks on the market. Seatylock, the brains behind the Foldylock have come out with some seriously impressive inventions, and have produced some of the most impressive locks I’ve used.

    Weighing just 2.2lb (1kg) the Compact is the lightest Sold Secure Silver folding bike lock on the market.

    When unfolded it’s 33.5” (85cm) long and offers a larger amount of locking space and more locking options than the U17.

    Folded away it’s silent whilst riding but its 5.5mm plates do mean it’s less secure than the U17.

    If you’d like a lightweight bike lock, that’s easy to transport and is suitable for use in mid-risk areas, the Foldylock Compact is the lock for you.

    Who Are Zefal?

    Zefal were one of the first cycling accessory manufacturers in the world. Since they began in 1880, they’ve constantly been working to expand and increase the quality of the products they offer.

    Zefal have strict quality control processes that make sure each product produced is just as durable and performs to the same standard as the last. As Zefal say themselves, “Quality, our key commitment in our product philosophy”.

    From plant-based mudguards to bike protection armour, if you need an accessory for your bike, Zefal have you covered.

    Summary - Zefal K-Traz U17 Review

    I like the Zefal K-Traz U17. Usually with budget bike locks the locking mechanism is likely to be sticky. Fortunately, the U17 works fluidly and I’m yet to experience any issues with its locking mechanism.

    The mounting system supplied with the U17 isn’t Zefal’s finest work, this is to be expected from cheaper locks because cost has to be cut to keep the overall sale price down.

    Thankfully, you won’t struggle to fit the K-Traz U17 into your backpack, so transporting this D Lock shouldn’t be an issue.

    With its Sold Secure Gold rating and quad bolted shackle, the K-Traz U17 is a respectable choice of bike lock. If you haven’t already, have a look at my reviews of the OnGuard Brute & Pitbull, two very similar locks sold for a similar price.

    If the U17 isn’t the lock for you, have a read of some of my other recommendations below.

    As always, lock it, or lose it!

    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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