Pitfalls in Traffic? What makes large tourers' front-vehicle following "ACC" different from four-wheelers

Adaptive Cruise Control (ACC)" has been increasingly used in motorcycles in recent years, including large tourers. This function automatically maintains a safe distance while following the vehicle in front on highways and other roads, and is well known in four-wheel vehicles. However, ACC for motorcycles actually differs from the function in 4-wheeled vehicles in some respects, and care must be taken when using it. So, what are these differences?　Here, using Yamaha's Tracer 9GT+ Y-AMT and other models as examples, we introduce the features of ACC for motorcycles, the differences from 4-wheeled vehicles, and points to note when it is activated. We will also discuss the latest trends, such as KTM's 1390 Super Adventure S EVO, which was introduced in 2025, and other recent models that also employ almost the same features as 4-wheeled vehicles.

Difference between ACC and cruise control

ACC is now a familiar feature in 4-wheeled vehicles, and as anyone who drives a modern car knows, it allows the vehicle to cruise at a set speed on highways without accelerating, and when it catches up with the vehicle in front, it maintains a certain distance between the two vehicles and follows it. Motorcycles have long been equipped with "cruise control," or cruise control function, which allows the rider to maintain a set speed without accelerating. However, they were not equipped with a function that automatically followed the vehicle in front, requiring the rider's operation to catch up with the vehicle in front. However, recent models are equipped with radar sensors that allow the ACC to automatically maintain a distance, just like a car. This contributes to further reduction of fatigue and improvement of safety when touring long distances.

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Tracer 9GT+ Y-AMT with the latest features

So, what features does ACC on a motorcycle actually have?　Let's take the Yamaha Tracer 9GT+ Y-AMT, which employs the latest features, as an example.

This model is an advanced version of the Tracer 9GT with an 888 cc, three-cylinder engine and advanced driver assistance systems, including ACC, which follows the vehicle ahead. For its 2025 model year, the car's name has been changed from Tracer 9GT+ to Tracer 9GT+ Y-AMT due to the adoption of the Y-AMT electronically controlled shift mechanism. The main function of ACC is to first detect the presence or absence of a vehicle in front and the distance between vehicles using millimeter wave radar equipped on the vehicle body. Based on this information, ACC automatically controls the vehicle to cruise at a constant speed, decelerate if the distance from the vehicle in front is close, or accelerate to a set speed if the distance is far. ACC is activated when the vehicle is traveling at approximately 30 km/h or more (depending on the gear used). The distance between vehicles during follow-up driving can be selected from four levels. The system also features a "turning assist function" that detects when the vehicle is turning in a corner, etc., and suppresses the increase in vehicle speed or limits the following acceleration if there is a vehicle in front of the driver. This function also contributes to safety when cornering. In addition, when the rider turns on the turn signal to the overtaking lane and the system determines that the vehicle is in an overtaking condition, the "overtaking assist function" accelerates the vehicle more smoothly than when recovering normal vehicle speed. These various ACC functions help reduce rider fatigue when touring. The Tracer 9GT+ Y-AMT also features the "Radar Linked UBS (Unified Braking System)", Yamaha's unique front-rear linked braking system that, when the rear wheel brake is operated, moderately distributes braking force to the front wheels as well. When the rear wheel brake is operated, UBS distributes braking force to the front wheel as well, resulting in a good brake feeling. This model also features a function that automatically assists braking force if the rider's brake input is insufficient, despite the close proximity of the vehicle in front and the threat of a collision, by matching the UBS function with millimeter wave radar and a sophisticated 6-axis "IMU" system. This advanced function assists the rider in maneuvering to avoid a collision. In addition, the 2025 model year will also feature a new millimeter-range radar behind the vehicle. The 2025 model also features new features such as "Blind Spot Detection (BSD)," which detects vehicles approaching from behind and displays the information in the mirrors. Incidentally, as mentioned above, this model is equipped with the new Y-AMT electronic shift mechanism. This is a newly developed automatic transmission that eliminates the need for a clutch lever and shift pedal, allowing the driver to shift gears using a shift lever mounted on the steering wheel. In terms of main functions, both MT mode, which allows manual shifting with paddle shifters, and AT mode, which allows fully automatic shifting, are available. In particular, in relation to ACC, when the AT mode and ACC are activated, the Y-AMT automatically shifts gears according to the increase or decrease in vehicle speed as well as gear selection during constant speed driving. This also makes it the world's first control system for two-wheeled vehicles that can be entrusted to the system to shift up and down or maintain such shifts during follow-up driving, just as in a typical four-wheeled automatic vehicle.

The major difference from a 4-wheeler is in traffic jams.

In this way, the ACC in the Tracer 9GT+ Y-AMT is as highly functional as a 4-wheeled vehicle. It is important to note, however, that it does not have the "traffic jam following (or all-speed following)" function that is available on the latest 4-wheeled vehicles. This means, for example, that when ACC is activated, if the car in front stops in traffic, for example, your car will automatically stop. When the car in front starts again, the system resumes following the car in front by the driver's operation or other means. On the other hand, the Tracer 9GT+ Y-AMT's ACC can be set to cruise at a minimum speed of 30-50 km/h (depending on the gear) and a maximum speed of 160 km/h. For example, if the speed drops below 25 km/h in first or second gear, the function will automatically stop. (Again, the minimum speed varies depending on the gear). Thus, when the vehicle in front stops in traffic jams or other situations, the rider on the following motorcycle needs to operate the brakes. The speed range supported by radar-connected UBS is 30 to 150 km/h, and the function of UBS itself is not activated unless the rider operates the brakes when ACC is not in use, such as on ordinary roads.

What is the reason for limiting these functions at low speeds and when stopped?　According to Yamaha's developers, the reason is that "if the motorcycle brakes on its own when the rider is not consciously applying the brakes (e.g., in traffic jams), the rider may be thrown forward by the unexpected braking, and in the worst case, the rider may be thrown forward. In particular, unexpected braking during cornering increases the danger to the rider. This is because a motorcycle, whose center of gravity shifts back and forth with acceleration and deceleration, is not as stable as a car with four wheels. And these settings are the same for many other models with ACC functionality. For example, in the Kawasaki Ninja H2 SX SE, the system deactivates when the speed drops below a certain speed set for each gear. This means that the rider must operate the brakes himself when the car in front stops in traffic or when his own car also stops. In this regard, the same applies to models made by European manufacturers equipped with ACC functionality. For example, the Ducati Multistrada V4S/S Sport and BMW R1300GS Touring also basically deactivate the ACC function when stopped, so the rider must operate the brakes, etc. .

KTM's new model also has an automatic stop function

Such ACC for motorcycles, KTM's 1390 Super Adventure S EVO (not available in Japan as of December 5, 2025) is attracting attention with its 2025 model year ACC that also performs fully automatic stopping. Based on the 1290 Super Adventure S, an adventure model that boasts high performance in both on-road and off-road driving, this model has an enlarged displacement of 1350 cc, increased power, and other improvements. A major topic is the adoption of the KTM AMT, which automates clutch operation. The clutch lever is not equipped, and the left switch box is equipped with a fingertip switch for shifting gears, allowing the rider to shift gears at will. The Bosch ACC, which was also used on the previous generation model, has been upgraded with brake assist, collision warning, and distance warning. In addition, in conjunction with the KTM AMT, the system can automatically stop and restart when the vehicle in front of it stops. Just like ACC with a traffic jam following function on a 4-wheeled vehicle, the system automates riding operations to the utmost limit, allowing for fatigue-free touring.

As if in response to the functional evolution of cars, advanced driver assistance systems such as ACC are gradually being updated for motorcycles as well. With these technological advances, we can look forward to a world in which motorcycle accidents will be greatly reduced in the near future. Go to  (9)