Alarm, monitor, and track your bike.


theft prevention rate*

*according to our own research through the AlterLock app.


devices sold

AlterLock is an alarm/GPS tracking security device for bikes. It lets you keep a remote eye on your bike and notifies you on your phone when the device detects movement while the bike is locked away.

Main Features


If the AlterLock device detects motion from your bike while in Lock mode, it will blare out an alarm that is as loud as 95dB, which is louder than a lawnmower, almost just as loud as a helicopter.

Alarms are highly effective in deterring theft, but you don’t have to worry about the embarrassment of a loud alarm being set off accidentally. AlterLock can be set to emit a relatively quiet warning sound the first time it detects your bike is being moved. If further movement occurs, indicating theft, the device sounds a loud alarm to scare off the thief.


When motion is detected, the AlterLock app will notify you on your phone with its own notification sound, so you can distinguish it from other notification sounds like email and realize you need to get to your bike straight away.

The app also gives you complete control over the device. You can turn Lock mode on and off, configure the alarm, and set the motion detection sensitivity. The app also lets you control up to three devices.
The app also automatically connects to the device in the background. As long as your smartphone is in close proximity, you can turn Lock mode on and off by pressing the button on the AlterLock device itself without opening the app. This means you can take a break from riding and be back in the saddle as soon as you’re ready to go again without the hassle of taking your gloves off or getting your phone out.


In the unlikely event that your bike is stolen, AlterLock can track it once a minute all the way to its final destination. If the bike is moved indoors where there is no GPS signal, the device uses Wi-Fi signals to determine its approximate location. This can also provide clues if the bike is abandoned or when the police search for it.

What sets AlterLock apart from many other tracking devices is its ability to track its location independently of your smartphone. By employing a highly accurate GPS module and Sigfox communication to connect to the Internet, the device transmits location information even if it’s hundreds of kilometres away, unlike Bluetooth, which has a maximum range of about 100 metres.


Easy Installation

  1. Download and install the AlterLock app.
  2. Subscribe to the BicycleGuard Service.
  3. Register your bike and device in the app.
  4. Mount it on your bottle cage and turn the lock mode on.

Product Comparison

Comparison with Bluetooth / GPS trackers

AlterLockBluetooth trackerGPS tracker
Movement detection alarm
Smartphone notifications– *1
GPS tracking after theft– *1
Real-time GPS tracking
Battery life
The size of the device
Mounting on road bikes
Comparison with general products.

*1. Only within bluetooth range

Differences from Bluetooth trackers

Bluetooth trackers use your smartphone’s location to track your device. They’re super-lightweight and consume very little power, making them ideal for searching for lost items at short distances.
AlterLock is equipped with stand-alone communication and GPS, so it can be tracked anywhere in its communication area.

Differences from GPS trackers

GPS trackers are perfect for recording travel routes because they acquire location information at regular intervals. However, because of this, GPS tracking has very high power requirements and often runs for only a few dozen hours before the battery is exhausted.
AlterLock uses GPS in conjunction with an accelerometer only in the event of theft, so it can be tracked for weeks.

Our commitment to aerodynamics

Nowadays, exceptional aerodynamic performance is the hallmark of a road bike. We’ve kept this in mind in designing AlterLock.
AlterLock is an anti-theft device, but it’s been improved in terms of size and aerodynamics so you don’t have to sacrifice your bike’s aero performance.
We’ve perfected a device that allows all cyclists, from beginners to pros, to focus on riding in the confidence that they’re not being slowed down.

At 40 km/h, the Cd value is +0.00062. That’s less than an extra 0.01 seconds travel time per hour.

Tech Spec

Size: 159×38×9mm
Weight: 50 g
Battery type: Lithium polymer
Battery life: up to 1.5 months/charge *1
Charging Socket: USB Type-C *2
Operating Temperature: -20 to 60°C
Charging Temperature: 0 to 45°C
Communication: Bluetooth Low Energy / Sigfox
Tracking: GPS (GNSS) / Wi-Fi
Protection: Water/Dustproofing IP66

*1 Varies according to use
*2 Charging cable is NOT included

1) Start Guide,
2) 2 regular mounting screws,

*Our package does not include a charging cable inside.

2 security screws, a special tool
*Only sold together with the device

Phone App

Compatible with BLE-equipped smartphones running Android 5.0 and above or iOS 11 and above.


AlterLock fits neatly on bottle cage bosses of most sports bikes and can be mounted underneath a bottle cage.

When in lock mode, removing motion will be detected on the device and will trigger the alarm to notify on your phone. This will make removing the device very challenging. We also sell anti-theft bolts separately to make extra sure that the device will not be removed.

Bluetooth-based trackers are primarily intended to prevent the loss of portable items. They transmit location information when a smartphone is in the vicinity, but are not suitable for tracking moving bicycles.
AlterLock has a stand-alone communication function and supports GPS / Wi-Fi positioning, allowing you to track wherever you go.

Typical Bluetooth-based trackers can only communicate within the range of a Bluetooth connection, making it difficult to track them once they leave out of your hand. However, AlterLock uses GPS and Wi-Fi positioning, so it can be tracked anywhere.

The frequency and duration of the alarm and the motion detection sensitivity can be adjusted using the AlterLock App.

To see if the area you are trying to use AlterLock is within the range of Sigfox,
please visit this page.

The European version is available in the following countries:
Austria, Belgium, Croatia, Denmark, Estonia, Finland, France, Germany, Greece, Ireland, Italy, Latvia, Lithuania, Luxembourg, Netherlands, Poland, Portugal, Spain, Ukraine and United Kingdom.

The Japan version will only be available in Japan.