How Does Motorcycle Blind Spot Radar Work?

Motorcycle blind spot radar is a small module at the rear of the bike that sends out 77 GHz radio waves, picks up their reflections from vehicles behind and beside you, and uses them to calculate distance and closing speed. When someone enters your blind spot or approaches too fast, an LED by the mirror lights up. Radar doesn't need light, so it works the same in sunshine, rain, dust and at night.

In cars this has been standard for well over a decade. Riders, who need to know what's happening behind them even more, were left with mirrors and a look over the shoulder. The CHIGEE SR-1 changes that: an automotive-grade radar designed for motorcycles that adds blind spot monitoring, lane change assist, rear collision warning and an overtake alert to practically any bike.

What the CHIGEE SR-1 is

The SR-1 is a rear-facing millimeter-wave radar built from the ground up for motorcycles, not carried over from a car. The module sits at the rear of the bike, two LEDs go by the mirrors, and a single harness connects everything to the 12 V system. The radar switches on once you pass the set activation speed and from then on continuously scans the space behind you. The factory setting is about 10 km/h, and in the settings you can choose 0, 10, 30 or 50 km/h.

A camera needs light and contrast. Radar only needs an object that reflects waves. Where a camera loses the picture in darkness, glare, rain and fog, the radar keeps transmitting in the 76-77 GHz band and uses the reflections to identify vehicles by size, distance and relative speed. That is exactly why CHIGEE built the SR-1 around radar rather than another camera.

Why 77 GHz and not 24 GHz

The first motorcycle radar accessories worked in the 24 GHz band, familiar from older car systems and industrial sensors. The SR-1 uses the 77 GHz band, which the automotive industry has adopted as the standard for driver-assistance systems. For you that means two things.

Precision: at 77 GHz the radar measures distance and relative speed to within millimeters, so it is better at telling a vehicle that is closing in from one that is simply riding alongside. And resistance to interference: higher frequencies react far less to signs, street lamps, barriers and electronics in dense traffic. Fewer false alarms, more trust in what the LED tells you.

The module itself is built to automotive standards. From early 2025 to April 2026 the CHIGEE test team rode with the SR-1 on real roads in different parts of the world, fine-tuning the timing of warnings and the filtering of false alarms.

In practice it works like this: antennas in a 2Tx/4Rx layout cover 110° horizontally and 90° vertically, up to 70 meters behind the motorcycle. The module's electronics work out which objects are vehicles, where they are relative to your lane and how fast they are closing in. Finally, the LED by the mirror lights up or flashes, depending on which of the four scenarios has been triggered.

Four warning modes

The SR-1 has four warning modes. Each runs on its own algorithm and watches a different situation on the road. They work in parallel.

BSD, blind spot

Watches the zone up to about 10 meters behind you in the adjacent lanes. The classic "car next to you": someone overtaking you, riding alongside at a similar speed or sitting where your mirror can't show them. The LED on that side stays lit.

LCA, lane change assist

Looks further back, up to about 70 meters in the adjacent lanes, and has no fixed warning distance. The faster someone approaches, the earlier you get the signal: with a speed difference below 20 km/h about 3 seconds before the risk, at 20-60 km/h about 5 seconds, above 60 km/h about 10 seconds. This is the mode that keeps you from moving into a lane where someone is coming at motorway speed.

RCW, rear collision warning

Focuses on about 10 meters directly behind the motorcycle. When a vehicle behind you is closing in so fast that it crosses the time-to-collision threshold, all the LEDs start flashing rapidly. This is the "someone is about to hit you" alert.

AOA, overtake alert

Kicks in after you overtake someone. In the same 10-meter zone as BSD it tracks the vehicle you have just passed. If instead of dropping back it stays alongside you, the LED on that side lights up.

A radar you can see from behind

Most blind spot systems stop at informing the rider. The SR-1 also has a rear-facing warning light. When someone is closing in too fast, the light signals your presence before they notice you themselves. It helps most at night and in poor visibility, which is when a motorcycle is hardest to see and rear-end collisions happen most often.

Rules on additional lighting differ between countries, so the rear light can be switched off in the settings.

How the LEDs warn you

Two LEDs by the mirrors, on 3M tape or on a bracket for the M10 screw in the mirror stem. The signal is directional: a vehicle on the left lights the left LED, on the right the right one, and when someone is closing in too fast from behind, both flash. Three different signals, without looking at any screen.

The LEDs sit at the edge of your vision, so you get the information at the moment you glance at the mirror anyway. They set their own brightness: in sunshine they cut through the glare, at night they dim so they dazzle neither you nor the drivers behind you.

Paired with a CHIGEE display, you get a second channel: a radar view with the vehicles around you appears on the screen, like on a ship's radar, and the LEDs are joined by audible warnings from the display's speaker.

Settings

Out of the box the SR-1 is set up for ordinary road riding. From a CHIGEE display or the CHIGEE GO app you can change three things: sensitivity, activation speed and alert intensity. Lower sensitivity in town calms alerts from cars in farther lanes, higher sensitivity sharpens the response on the open road. You can set the activation speed to 0, 10, 30 or 50 km/h. Intensity decides how insistent the LEDs are.

Installation

Everything is in the box: the radar module with its bracket, two LEDs, two M10 mirror brackets, a harness with a 3 A fuse, quick connectors for the ACC circuit, Torx keys, 3M tape and cable ties. Most people finish the installation in a weekend with basic tools.

You start at the rear. The module mounts horizontally, 30-100 cm above the ground, with a clear view backwards: under the tail, on the license plate bracket or by the luggage rack. The LEDs go to the left and right mirrors, on tape or on the M10 bracket where the mirror has no flat surface. Finally the harness: red to battery positive, black to negative, yellow to the ACC circuit, so the radar switches on with the ignition.

Have a CHIGEE display? You pair the radar under Settings, Function, Blind Spot Monitoring, Millimeter-wave Radar. The display switches blind spot monitoring from the cameras to the radar on its own and unlocks the sensitivity, activation speed and sound settings.

Large panniers, a top case or a sports exhaust can block the radar's view. Usually moving the module is enough, with no changes to the motorcycle.

On its own, with a display or in the mirrors

In its simplest form the SR-1 radar works on its own: the LEDs from the kit give you full warnings without any display. This is the option for someone who wants radar but doesn't want to build a whole system on the handlebar.

With an AIO-6 or AIO-5 EVO display you add a radar view on the screen, sound from the speaker and full sensitivity control. If you already ride with CHIGEE, it's the natural pairing.

The cleanest cockpit comes with CHIGEE mirrors with LED indicators, where the LED sits in the mirror glass, right in your line of sight. No external module, as if it came from the factory.

One rule: a display pairs with one radar at a time. Two motorcycles with an SR-1 each and one AIO-6? Before pairing with the second radar, delete the first pairing in the settings.

What the radar doesn't see

Range depends on how well a vehicle reflects the waves: a truck reflects more than a car, and a car more than a motorcycle, so large vehicles show up from far away. Slow-moving traffic gives a weaker signal than a vehicle closing in fast. On a tight bend the scanning zone shrinks to whatever fits in the radar's field of view. Ordinary rain makes no difference, but dense fog and a downpour weaken the waves at the longest distances.

The SR-1 is made for motor-vehicle traffic. A bicycle, a pedestrian or a stationary object with a weak reflection may not be detected. It's an assistant: it complements your mirrors and the look over your shoulder, but doesn't replace them.

It helps most where mirrors fail: after dark, in dense multi-lane traffic and on long, tiring stretches. It fits most road, adventure, touring and cruiser motorcycles, as long as the rear gives the radar a clear view. The housing is rated IP69K, so a downpour or a pressure washer won't bother it. See the SR-1 radar or the mirrors with LED indicators.

Frequently asked questions

Do motorcycles come with factory blind spot radar?

Rarely. Ducati, BMW, KTM, Kawasaki and Yamaha offer factory radar (front, rear or both) on their top models, usually as an option. That shows how important the technology has become. The CHIGEE SR-1 brings the same function to practically any motorcycle, whatever the brand or model year.

Why 77 GHz and not 24 GHz?

77 GHz is the automotive standard for driver-assistance systems. It measures distance and relative speed more precisely and reacts less to signs, street lamps and other electronics. The result: more accurate warnings and fewer false alarms.

Radar or camera for the blind spot?

Radar works in darkness, fog and rain, where a camera loses the picture, and it measures distance and speed directly. A camera is better at recognising what an object is, but it depends on light.

Does the radar work in traffic jams?

It depends on the activation speed you set. From the factory the radar switches on at about 10 km/h, so that alerts don't go off constantly at walking pace. In the settings you can choose 0, 10, 30 or 50 km/h; at 0 km/h the radar is always on.

Will I hear the warnings in my intercom?

No. Sound plays only from the speaker of a paired CHIGEE display and isn't passed to a Bluetooth headset. Without a display you get warnings through the LEDs only.

Do I need a CHIGEE display?

No. The SR-1 works on its own. Pairing with an AIO-6 or AIO-5 EVO adds a radar view on the screen, sound, radar-based blind spot monitoring instead of camera-based, and sensitivity control.

Can one display handle two motorcycles with radars?

Not at the same time. To switch to the other motorcycle, delete the current pairing in the settings and connect to the second radar.

Will the SR-1 fit my motorcycle?

All it needs is a 12 V system with an ACC circuit and a spot at the rear with a clear view behind the bike. With large panniers you sometimes just need to move the module.

What does IP69K mean?

Full protection against dust and resistance to high-pressure, high-temperature water jets, the standard for vehicles that get steam-cleaned. In practice the SR-1 doesn't mind a downpour, road spray or a pressure washer.