The Secret Hidden in the Parameters (Part 2)

What does cam lift mean?

What are the effects of valve overlap angles on different models?

How does the large forward extension angle and drag distance correspond to the handling performance?

What is the difference between a sports car and a station wagon's human-machine triangle setup?

What are the kerb quality, net mass, payload, and total mass?

……

Concept and manipulation,

parameters and performance,

How closely are they related?

Motorcycles are machines, industrial products, emphasizing data quantification, using various concepts, parameters to define and describe performance, such as forward angle, towing distance, wheelbase, man-machine triangle, net mass and curb weight, valve overlap angle, cam lift, power, torque... However, motorcycles are also riders' cars, and they need to give riders richer feedback and more experience, and those data are too blunt, too cold, and difficult to understand. In the end, what function are these concepts of motorcycles used to describe? What kind of performance do these parameter indicators correspond to? Let's explore the story behind the important concepts and parameters of motorcycles through "car to tell".

Turn geometry

Parameters directly related to the steering performance of the motorcycle are mainly the forward extension angle, towing distance and offset. The forward extension angle is the angle formed by the extension line of the steering column and the vertical line that passes through the shaft of the front wheel, the larger the forward extension angle, the more blunt the steering, and the better the linear stability. The towing distance is the length of the projection on the ground after the extension line of the steering column crosses the vertical line passing through the front wheel axis, and the larger the drag distance, the more stable the straight driving and the more blunt the steering. The offset is the distance between the extension line of the steering column and the parallel line passing through the axle of the front wheel, and the greater the offset, the more flexible the steering, and the stability of the straight driving decreases.

The steering geometry of each model is different, and the difference between a sports car and a cruise car is more typical, because the former is a high-speed model that often attacks and corners quickly and requires a keen steering response, and the latter is a casual model that is good at running straight lines, emphasizing the rock-solid riding characteristics.

The Harley FXDR 114 is a classic American cruiser that emphasizes unhurried acceleration, a bold driving posture and comfortable riding performance. To this end, the FXDR 114 is equipped with a 114 cubic inch engine, which is an increase of 123mL compared with the 107 cubic inch engine of the same door brother, reaching 1868mL, which is definitely a "big man". The V2 engine of the FXDR 114 uses a bore and stroke of 102mm ×114mm, with a compression ratio of 10.5:1, and under the servo of the latest generation of electronic fuel injection system, it can burst the maximum torque of 161N·m, while the speed is only 3500r/min, and the low-speed torque is extremely powerful. Considering that the V-twin engine is rigidly mounted to the frame and has a huge displacement, in order to improve riding comfort, Harley engineers installed a double reverse balance shaft for this engine, which effectively reduced the vibration during idling.

The FXDR 114 features a mild steel tube frame with a low and long vehicle shape. The swingarm is completely redesigned and made of aluminium alloy material, which reduces the weight of the steel swingarm of the same door brother by up to 43%! Harley claims that this move effectively improves the performance of the rear shock absorber due to the significant reduction in the under-spring mass. The saddles and tail are supported by a subframe, and unlike the siblings, the FXDR 114's subframe is not made of steel, but is welded from aluminum steel tubes, further reducing the mass.

Corresponding to this dynamic characteristic and frame setting, Harley engineers adopted a larger steering geometry that emphasized rock-solid straight-line running performance. The FXDR 114 has a backsloping angle of 34°, an increase of around 40% compared to a supercar, and a towing distance of 119 mm, which is also an increase of around 20%. This large steering geometry setting, although the FXDR114 can not be compared with the supercar in the corners, but has an exceptionally stable straight driving performance, running on the road easy to stretch, heroic atmosphere.

Human-machine triangle

The human-machine triangle is actually about the driving posture. When the rider steps on the motorcycle, there are three main contact parts with the motorcycle, namely the hand - handlebar, the foot - pedal, and the hip - cushion. The connection of these three contact points constitutes a human-computer triangle. The human-machine triangle is directly related to the riding comfort and handling characteristics, and different types of motorcycles use different man-machine triangle settings.

For sports motorcycles, the pursuit of speed and handling performance, riding comfort is the second thing. Therefore, in terms of human-machine triangle setting, this idea is also highlighted, and the Kawasaki ZX-10R is a typical example. As we all know, Kawasaki has had a smooth ride in the Superbike Championship in recent years, and since 2015, it has occupied the championship of the WSB arena for five consecutive years, and it is a double champion, including the rider championship and the manufacturer championship. The Kawasaki Warhorse ZX-10R has an unusual energy, this 998mL liquid-cooled, DOHC 16-valve side-by-side four-cylinder engine, the maximum torque increased to 114.9N·m (11200r/min), the maximum power reached 149.3kW (13500r/min), and when the forced intake system is activated, the maximum power will soar further, up to 156.8kW (13500r/min), which is very exciting!

Just as important as increasing the power is to reduce the wind resistance, air resistance is to consume engine energy, prevent the speed of the road blocker, and "the road is one foot high, the magic is one foot high", when the rider runs to a certain speed, it will become more and more difficult to increase the speed. Therefore, sports motorcycles will take measures such as reducing the windward area to achieve the goal of reducing air resistance and increasing speed. The ZX-10R features a low drag deflector and windshield to optimize the aerodynamic design. The rider's wind resistance can also not be ignored, so Kawasaki engineers raised and moved the foot position up and backwards, the handlebar position was installed lower, and the 835mm seat height was relatively high, so that the rider formed a clear forward-leaning driving posture and distributed more weight to the front end. Especially when galloping at high speeds, it is convenient for the rider to lie tightly on the fuel tank and curl up behind the windshield, thus effectively reducing the resistance of strong airflow.

The human-machine triangle setting of the touring motorcycle is the opposite of that of the sports motorcycle. Take the "Big Mac" Triumph Rocket 3 GT as an example,

As a road heavy brigade, comfort is placed first, paying more attention to ergonomics, driving and riding is more relaxed. The first is that the wheelbase reaches 1677mm, providing more space for riders and passengers, even if it is a big man, sitting on it looks stretched naturally. Secondly, the seat height is only 750mm, the rider's feet can easily land on the ground; the rider's foot pedal is slightly forward and lowered to make room for the legs to be comfortable and natural; the handlebar is installed in a higher position and then naturally swept back. The human-machine triangle composed of saddles, pedals and handlebars allows the rider to form a relatively upright driving posture, which is particularly comfortable and heroic to drive.

Curb weight and net quality

It should be said that among the various parameters of the motorcycle, the most popular concept is weight, because this concept is in contact with us at any time in daily life, in fact, the weight we say in layman's terms is often quality. If you dig a little deeper, you'll see a lot of things hidden behind the weight. Motorcycle weight has a variety of divisions, such as net mass, curb weight, curb weight, payload, total weight, etc., which method is used, different countries have different practices, and even the definition of the same division may be slightly different. In general, net mass refers to the weight without liquid, that is, the weight of the motorcycle fuel tank without gasoline, the crankcase without oil, the radiator without heat dissipation, the brake system without hydraulic oil, etc., which belongs to the weight of the motorcycle when it is the lightest. The curb weight, on the other hand, is the weight of the motorcycle when it is filled with liquid, and the motorcycle is only available under the curb weight state. In general, the quality of maintenance is another term for the quality of maintenance. The total weight is the sum of the motorcycle's curb weight plus the rider' and passenger's weight and luggage weight. Payload refers to the rider, passenger and baggage weight that the motorcycle can withstand.

The weight varies greatly from model to model. In general, motocross is the lightest of the various models. In the case of a 250mL liquid-cooled single-cylinder engine, the KTM off-road vehicle EXC 250 is exceptionally lightweight – in order to steal light and reduce weight, KTM engineers use a lightweight chrome-molybdenum alloy steel tube frame to enhance lateral rigidity, longitudinal rigidity and torsional rigidity while focusing on weight reduction, and the subframe uses aluminum alloy square tubes. The EXC 250 ranks among the slimnest, lightest, and most responsive arrays in its class, weighing only over 100kg if there is no fuel in the tank; even if it is filled with gasoline, the whole vehicle weighs only about 110kg, which is about 20kg lighter than the ordinary 125mL street car!

The first-class model, which focuses on comfort and enjoyment, is heavily weighted due to the use of a large engine and various auxiliary devices. Armed with a large V2 engine with a displacement of up to 1854mL, Yamaha Star Venture adopts Yamaha's well-mastered twin spark plugs, diagonal top combustion chamber, and 4-valve cylinder head technology. Given Star Venture's expeditionary mission, Yamaha also installed a mini oil radiator between the front and lower tubes of the Star Venture frame to ensure that the engine was in ideal working condition.

Star Venture's travel equipment has everything, such as an easy-to-park system equipped with an electric motor, allowing riders to easily move the Star Venture, just through the control buttons on the handlebar, you can achieve safe slow forward or backward movement; the infotainment system includes a vehicle control center, communication devices, advanced sound systems, etc., adding a lot of life to the journey; the standard heated handlebars, heated rider cushions and backrests, heating passenger cushions and backrests, so that you can whether you are in the cold and windy early winter, It is still in the cold late autumn, and it is warm all the way when traveling. Therefore, Star Venture is strong and powerful, and the quality of the tank is as high as 434kg!