Alterlock anti-theft GPS tracking device review

The reality is that once a bike is stolen, the likelihood of recovering it is extremely low. Alterlock’s GPS tracker looks to change that by offering a huge 1.5 months of GPS tracking amongst other anti-theft features

(Image: © Graham Cottingham)

Cyclingnews Verdict

Passive protection against bike theft with smart accelerometer battery-saving abilities. While it probably won't stop a bike thief, at least you should have a better chance getting your bike back


  • +

    Accelerometer activated tracking saves battery

  • +

    GPS module, Sigfox communication and WiFi has a huge tracking range

  • +

    Lightweight and unobtrusive


  • -

    The initial cost is expensive and the subscription service adds further monthly costs

  • -

    Can easily be removed unless additional special security bolts are purchased

  • -

    USB-C charging cable not included

  • -

    Another thing to remember to charge

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Bike theft is unfortunately a very real reality, whether it’s from outside the café, locked in the street or stored in your garage. In many circumstances, the best bike locks are going to make sure your bike is still there when you come back. That said if a thief wants your bike badly enough, not even the largest D-lock is going to stop them.

Alterlock is an alternative approach to bike security, offering an alarm and long-range GPS tracking and communication functionality that should allow you to track down and recover your bike if the unthinkable happens. 

However how well does it perform against the best bike GPS trackers? Is it a game-changer, or should you still opt for the best bike insurance you can find, to be safe?

A side view of the Alterlock fitted to a bike

Alterlock fits to the bike using the bottle cage mounts (Image credit: Graham Cottingham)


Fitment is as simple as fitting a bottle cage and, unless you have a very unconventional frame, will fit across road, gravel and mountain bikes. As the Alterlock adds 9mm of depth, you won’t be able to use your standard bolts, but Alterlock includes some extra long bolts with 3mm hex key heads. Once fitted, it’s secure and out the way. Another advantage of being under the bottle cage is that it is shielded from front wheel spray, although the Alterlock is IP66-rated (waterproof), so you shouldn’t need to be worried about riding in all weathers. 

For those concerned about aero considerations, Alterlock says that the device only adds a Cd value of +0.00062 at 40kph. Meanwhile, if weight is an issue for you, Alterlock only weighs 50g, making it still a lighter option than even the best lightweight bike locks.

The system process when in use has three phases. Once locked, if the Alterlock detects vibrations it makes a warning noise as well as sending a notification to your phone. If the vibrations continue to be detected, the 95dB alarm will be activated and the Alterlock will start transmitting its location. Subsequent vibrations won’t reactivate the alarm, and instead, the Alterlock will quietly notify you of its location after each subsequent vibration so you can track its last location.

Tracking is performed through GPS and WiFi to try and cover as many bases as possible. GPS provides accurate location services and if the bike is stashed inside then the Alterlock will use Wi-Fi to determine its location. While Bluetooth is used to connect to your phone, once out of range the Alterlock switches to Sigfox communication which is able to send location information over long distances with low power draw. The Lithium polymer battery is charged via a USB-C cable and rated to last 1.5 months, giving plenty of time to locate your bike. 

The app itself is fairly self-explanatory to use. It's split into two main tabs: one for controlling and tracking the Alterlock device, and another with bike information and maintenance data. Maintenance and component data recording is a nice touch, and the amount of data that can be documented is pretty comprehensive to help you keep track of everything from when you last cleaned your chain to when you upgraded your handlebars. There is also access to account data and settings too.


While the alarm will certainly deter some opportunist thieves or at least alert you or someone else to intervene, it will not put off the most brazen robbers. This is obviously where GPS and Sigfox functionality kicks in and lets you track the bike. The effectiveness of this is in the thief’s hands though. If they become too annoyed by the alarm noise or they are bike tech-savvy, then the thief can simply remove the alarm with a 3mm hex key and toss it at the nearest convenience. Obviously, the thief would need a multi-tool handy and the use of the security bolts would make this much harder (but they are an additional cost at the time of purchase). If the thief is very tech-savvy, then they could simply press the physical button on the Alterlock before making off with your bike and you would potentially be none the wiser until you returned to find your bike missing.

The customisation of vibration detection sensitivity is a nice touch that should extend the Alterlocks range of use, this means it isn’t limited to protecting your bike while you nip into the shops but also if you want to use it on the back of the car or van. 

GPS accuracy is always going to be dependent on location, and if the thief hordes your bike inside a building to wait for the heat to blow over, you will lose signal. This is where the Alterlock switches to using Wi-Fi networks to determine its location, though obviously this is not going to be as accurate as GPS and is compounded if the thief lives in a densely populated area. It also isn't able to distinguish vertical position, so if your bike is in a multi-storey building, locating it would be very difficult as well.

A rear quarter perspective of the Alterlock fitted to a bike

Alterlock's reasonably small form should mean it's not noticeable once fitted to the bike with a water bottle  (Image credit: Graham Cottingham)


If you are looking for a way to track down your pride and joy, having the Alterlock fitted is probably going to be your best bet. The trifecta approach to location tracking, paired with the battery-saving accelerometer, should hopefully give you enough time and accuracy to organise your local authorities to recover your bike. The form is neat as well, simply fitting under the bottle cage with almost zero effect on the performance of the bike. The app provides plenty of customisation for the functionality and sensitivity as well as the actual setting of the alarm and bike tracking.

That said, other than an annoying-sounding alarm, and the resulting scramble of cycling shoes on a café floor, there isn’t anything stopping an opportunistic bike thief from trying their luck. Meanwhile, products like Hiplock’s FX cable lock only costs £20 (less than the yearly subscription needed for Alterlock) and creates a tangible barrier that stops someone from riding away on your bike. Bear in mind Hiplock’s FX lock is going to be easily cut, but if a bike thief is cruising around with a set of bolt cutters they probably aren’t going to be put off by an alarm either.

Thinking of getting your bike insured? Compare bicycle insurance (opens in new tab) to find yourself the best deal.

Tech Specs: Alterlock Anti-Theft Tracker

  • Price: £114.99 / €134.99 (£3.49 / €3.99 monthly subscription, £34.99 / €39.99 yearly)
  • Weight: 50g
  • Location detection: GPS, Wi-Fi
  • Service area: Europe
  • Colour: Black

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