Product Overview
The Fosmon Anti Theft Bike Alarm is designed to provide robust security for your bicycle, e-bike, scooter, motorcycle, cart, or trailer. It features a loud 113dB siren, a sensitive vibration motion sensor, and a remote control for convenient operation. The system is waterproof and offers multiple adjustable settings to suit various environments and security needs.

This image displays the two Fosmon bike alarm units and their corresponding remote controls included in the 2-PACK.
Setup and Installation
Before installation, ensure the alarm unit has fresh batteries installed (2 AAA batteries, included). The alarm offers two primary installation methods:
Installation Methods

This diagram illustrates the two methods for mounting the alarm: using zip ties for secure attachment to a frame, or using double-sided tape for flat surfaces.
- Zip Ties Installation: Thread the cable ties through the brackets on the back of the alarm. Run them through one or both of the provided channels. Wrap the zip ties around the desired installation area (e.g., bike frame) and pull them tight to ensure a secure fit.
- Double-Sided Tape Installation: Thoroughly clean and dry the desired surface area. Apply the provided adhesive tape to the back of the alarm and firmly press it onto the desired surface.
Pairing the Remote Control
An alarm unit can be paired with up to 8 remote controls. To pair a remote:
- Ensure the alarm is disarmed.
- Press and hold the 'Disarm' button on the remote for approximately 3 seconds until the alarm beeps once.
- Within 5 seconds, press the 'Arm' button on the remote. The alarm will beep twice to confirm successful pairing.
Operating Instructions
Arming and Disarming
- To Arm: Press the Arm button (closed padlock icon) on the remote. The alarm will beep once to confirm it is armed.
- To Disarm: Press the Disarm button (open padlock icon) on the remote. The alarm will beep twice to confirm it is disarmed.
Adjusting Sensitivity Levels
The alarm features 7 adjustable sensitivity levels, from lowest (triggered by strong impact) to highest (triggered by gentle touch). The default setting is level 4.

This image visually represents the 7 adjustable sensitivity levels, indicating how the alarm can be triggered from a gentle touch to a strong push or beat.
- While the alarm is disarmed, press the Lightning Bolt button on the remote.
- The alarm will beep to indicate the current sensitivity level (e.g., 4 beeps for level 4).
- Continue pressing the Lightning Bolt button to cycle through the levels. Each press will increase the sensitivity by one level, with 7 being the highest. After level 7, it cycles back to level 1.
- Stop pressing when you reach your desired sensitivity level. The alarm will automatically save the setting after a few seconds of inactivity.
Adjusting Volume Levels
The alarm has 3 volume levels. The default setting is the loudest (level 3).

This image highlights the alarm's powerful 113dB siren, designed to effectively deter potential thieves within seconds.
- While the alarm is disarmed, press the Bell button on the remote.
- The alarm will beep to indicate the current volume level (e.g., 3 beeps for level 3).
- Continue pressing the Bell button to cycle through the levels. Each press will decrease the volume by one level, with 1 being the quietest. After level 1, it cycles back to level 3.
- Stop pressing when you reach your desired volume level. The alarm will automatically save the setting after a few seconds of inactivity.
SOS Function
The SOS function detects if the vehicle is tilted more than 45° from its original position (e.g., after an accident) and emits a continuous beeping sound to signal for help. This function is off by default.

This image explains the SOS function, which activates if the device tilts more than 45 degrees from its initial position, and provides steps to enable or disable it.
- To Turn On SOS: Press and hold the Disarm button for about 6 seconds. The LED will turn off and then back on. The alarm will beep 1 time, followed by 5 beeps to indicate SOS is on.
- To Turn Off SOS: Press and hold the Disarm button for 6 seconds. The LED will turn off and then back on. The alarm will beep 2 times to indicate SOS is off.
Bike Finder Function
Use the bike finder function to easily locate your vehicle in a parking lot or crowded area. The remote control has a range of up to 230ft (70m).

This image demonstrates the wireless bike tracker function, allowing users to easily locate their bike from a distance using the remote control.
- To Activate: Press the Bell button on the remote while the alarm is armed or disarmed. The alarm will emit a series of loud beeps, helping you pinpoint its location.
Maintenance
The Fosmon Anti Theft Bike Alarm is designed for durability and minimal maintenance.
Water and Dust Resistance

This image highlights the alarm's IP65 rating, indicating its resistance to dust and water, making it suitable for various outdoor conditions.
- The alarm unit has an IP65 rating, meaning it is protected from total dust ingress and low-pressure water jets from any direction.
- While it is water-resistant, avoid submerging the device in water for extended periods.
- Clean the unit with a damp cloth as needed. Do not use harsh chemicals or abrasive cleaners.
Battery Replacement
The alarm unit requires 2 AAA batteries. The remote control uses a CR2032 button cell battery. Replace batteries when the alarm's sound becomes weak or the remote's LED indicator dims.
- Alarm Unit: Open the battery compartment on the back of the alarm unit, remove old batteries, and insert new AAA batteries, observing polarity.
- Remote Control: Carefully open the remote control casing, replace the CR2032 battery, observing polarity, and close the casing securely.
Troubleshooting
- Alarm is not loud enough: Check the volume setting (refer to 'Adjusting Volume Levels' section). Ensure batteries are not low.
- Alarm is too sensitive/not sensitive enough: Adjust the sensitivity level (refer to 'Adjusting Sensitivity Levels' section).
- Remote control is not working: Ensure the remote's battery is not depleted. Re-pair the remote with the alarm unit (refer to 'Pairing the Remote Control' section). Ensure you are within the remote's operating range (up to 230ft/70m).
- Alarm does not respond: Check the alarm unit's batteries. If the issue persists, try resetting the alarm by removing and reinserting the batteries.
Specifications
| Feature | Detail |
|---|---|
| Alarm Loudness | 113 dB |
| Sensitivity Levels | 7 adjustable levels |
| Volume Levels | 3 adjustable levels |
| Water Resistance | IP65 rated |
| Remote Control Range | Up to 230 feet (70 meters) |
| Alarm Unit Battery | 2 x AAA batteries (included) |
| Remote Control Battery | 1 x CR2032 button cell battery (included) |
| Item Weight | 249 g |
| Model Number | 51087HOM-2PACK |
Wide Applications

The Fosmon Anti Theft Bike Alarm is versatile and can be used for various applications, including bicycles, motorcycles, trailers, and scooters.
Warranty and Support
This Fosmon product comes with a limited lifetime warranty. For more detailed information regarding warranty terms and conditions, please refer to the official Fosmon website.
For technical support, troubleshooting assistance, or any product-related inquiries, please visit the Fosmon support page or contact their customer service directly. Contact information can typically be found on the Fosmon website.
