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AlterLocK Anti-Theft Alarm and GPS Tracking Device

 52g £119 Subscription £3.99/month

AlterLocK is a security device and data package that offers a loud alarm and tracking that can continue for several weeks. It is feels like a solid piece of gear that is held securely with a special tool. Granted, there can be issues with connectivity (similar to all devices) and some will argue that gear like this attracts the attention of thieves. Such arguments apart, it works, had many neat features, is tuneable, and all can be operated for your mobile.


Pros: loud, uses both Bluetooth and GPS, tuneable, long charge life, secure fitting tool included with device purchase, light, easy to see.


Cons: UK and Europe only (other packages are available), alarm is loud but needs to be within earshot, easy to see.


A slim plastic shell – the shape put me in mind of a rather flat shin bone, but that is probably just me - measues159 x 38 x 9mm and weighs in at around 50g. That may offend ultra-low-weight-weenies, but may be a sensible trade-off for others. In my case, touring and utility cycling for the most part, it seems largely irrelevant. As ever, horses for courses.


IP66 dust and water protection is almost as good as it gets. Dust and other problematic particles are unlikely to gain access, even via the charging port – sealed by a plastic plug. Waterwise, IP6 should prevent ingress in “heavy seas” (unlikely on your bicycle, but you never know) and powerful jets of water. Short of full immersion, there’s unlikely to be any harm done.

The lithium polymer battery is charged via USB type C port/cable, which when full claims to offer around six weeks life. Charging is stated to be best at 0-45C and operation at -20-60C. Even with climate change, this should be achievable for most folk.

The AlterLocK is controlled by an app on your smart phone. You can do some basics manually, but the fine tuning of sensitivity to movement and other preferences are on the app. This is available for iPhone and Android devices. Communication between device and AlterLocK  is by Bluetooth (low energy) and SigFox. Bluetooth is familiar to most. SigFox is designed to work independently or complimentary to other networks. It is low on battery consumption, specialising as it does in carrying small assets.

As well as having a 95 decibels alarm – that’s equivalent to a motorcycle engine running at 25 feet, an electric drill, an underground train (metro, subway et al) – the AlterLocK offers tracking using GPS (GNSS) and WiFi. These complement each other, which, in turn, aids battery longevity. Passing remote tracking data over a network requires, of course, connectivity. The extent to which that can be guaranteed can be dependent on location, as we’ll all know, and that need not meant the middle of nowhere. Our package is designed solely for Europe and the UK. Other packages are available, but make sure to check out which will suit you best: a big issue for intercontinental travellers.

The App 4.75/5

Old Fogey’s, amongst which I class myself, can easily be confused by techy terminology and so on. Fortunately, the App is intuitive and simple. Fundamentally, you can turn the alarm on and off with the padlock symbol. There are then two sections, self-explanatory, “Control” and “Info”. The first allows you to adjust the sensitivity level, change the periodic transmission data, allow notifications, and alter settings.


In the “Info” menu you can add information about your bike and set up a maintenance regime with reminders (e.g. charging). There’s also a general menu with account settings and so on.


For me, the most important thing is that it is easy to use. I guess there are some who would like it to talk to their GPS or their calendar etc., but I can’t think why.

Mounting 4.75/5

Alterlock is designed to fit under a bottle cage, so you really need the bosses for this. Of course, it does not matter which bottle cage.

A special tool comes with the package. Use the secure bolts provided. These have been long enough to go through quite chunky bottle cages as well as the device and hold solidly in the bottle-cage bosses. Simples. Be careful not to lose the special tool. It is not available as an after-market add-on, only with purchases. Charging may be awkward with the AlterLocK fixed to the frame! Of course, it canoe mounted wherever thee are appropriate bosses.

alterlock app

Performance 4/5

Having decided to go down the Alterlock line, and having got the basics set up on the bike and on your smart phone, things have been pretty impressive. Charging time has been around three hours (depending on power source), but I have tended just to leave it overnight as it is not the sort of thing that needs rapid charging, such as lights. Taking the Alterlock off the bike may be seen as a bit of a pest, but it is not a weekly festival. With a bit of luck toy may need to do it seven or eight times a year. I have not tried charging through a hub dynamo (Front wheel repairs), but there’s no reason why, with suitable equipment such as the Sinewave Beacon, supplementary charge could not be added on the go with a suitable length of cable.

Charge seems to last for a very long time, especially if you shepherd it carefully by turning off when not in required. Ours certainly functioned without re-charging over an eight-week period. Of course, there’s a lot of context here: the weather was warm and I tended to turn things off when the bike was securely stored.


The alarm is really intended to attract instant attention: outside a café, doing the shopping, outside your tent on a wild camp. 95 decibels should manage that. It’ll go silent after ten seconds (default), but this can be adjusted with the app – with a range up to a minute. You’ll react, of course, provided you are within earshot, whether anyone else takes any notice or not, who knows. The alarm can repeat up to three times. Uninformed guinea pigs jumped out of their skins when attempting to filch my bike.


Tracking seems very good, too. It certainly traced my machine on its journey from the North Midlands to the West Country and back very accurately: I checked the location

alterlock cycling bicycle security bottle cage test review

against Google Maps, Garmin gps, and other tracking apps frequently during the trip. The caveats are, of course, that this may not be accurate enough to be able to carry out a missile attack on bike thieves without causing unwanted collateral damage to the surroundings, and signal strength.

Attempting to shift the “secure” bolts with the usual torque tools and so on has been a total fail on my part. For obvious reasons, I have not attempted to smash the AlterLocK to smithereens.

Durability/care 4.5/5

There have been no problems with water ingress when left outside in torrential summer downpours. Frankly, with due care and attention, this robust bit of gear should last for many years. 

Value 4/5

Knog’s Scout comes in at under £50, but only functions though an iPhone, Apple Smart Watch, or iPad. Like the Alterlock it has tamper proof screws for mounting to the bottle cage. Tracking is via the Apple “Find My” app.


More sophisticated is the Sherlock GPS tracker, which is also some £70 more costly. It is designed to fit in flat or curved bars and has a SIM card with two years use on it. Subscription is required, but that is only £2.50, at the time of writing. A plus is that it is better hidden than most. Another plus is availability n the USA, as well as the UK and Europe. The big drawback is a very milted run time.


SeeSense Knowhere is around the same price, and offers seat mounting as well as bottle-cage location.


Then there’s the Boomerang Cyclotrac V2, which also offers clamp and rack mounting options. Price is around the same mark as the Alterlock. 


Then there are generic tracking devices, such as Air Tag.  These are generally limited to specific networks and are much more limited in their tracking capability. Nor are they alarmed.


The AlterLocK scores well in many areas. True, it may not be discreet, but there’s something to be said for shouting out that your bike is alarmed and secured. It has a very good run time and short charging time. I have not experienced any connectivity issues. With a very loud alarm and excellent GPS and Bluetooth tracking, it is certainly well-worth checking out if you are in the market for something to help protect your pride and joy.

Verdict 4.5/5 Effective and easy to use at a competitive price for this type of spec.


Steve Dyster





Ryton On Dunsmore

Coventry  CV8 3FH


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