The relationship between the engine and the rear wheels is not only limited to the simple relationship between power transmission and driving force generated after force. Furtherly, it is because that the tires are elastic.
Driving force and grip force
Elastic tires are squeezed every time they receive a force, and the tires are squeezed by power before transmitting it to the road. Part of the flat rubber is on the ground to release the power and drive the vehicle forward which creates the grip force.
We know more or less that the power of the current four-stroke engine is produced by each “explosion”. After the explosion, the piston generates thrust to drive the connecting rod to push the crankshaft, and the crankshaft transmits through the flywheel to cause the gearbox, which leads the gearbox to the chain and finally transmitted to the rear wheel. This is a very complicated and continuous action! Engine power only comes from the stroke of “explosion”, and other “inhalation, compression, and exhaust” are all preparatory actions for “explosion”. The so-called “driving force” will only appear after the force generated by the explosion is transmitted to the rear wheels, and the force when the engine is ignited and “exploded” is relatively transmitted to the road through the rear wheels. Each time these three strokes before the explosion is the so-called “ignition time interval”.
After the engine power is transmitted to the tires, it is transmitted to the ground evenly through the tires, and part of the force (yellow mark) is transmitted back to the tires. At low speeds, the ignition interval is long, so the engine power can penetrate the road completely, and the excess force will be absorbed by the tires.
After the engine power is transmitted to the tires, it is transmitted to the ground evenly through the tires, and part of the force is transmitted back to the tires. At high speeds, the ignition interval becomes shorter, and the remaining power that has not been absorbed by the tires is reproduced, so that the engine power cannot be completely transmitted to the ground and the grip is reduced.
Anything that is elastic will deform to varying degrees when it is squeezed to lie flat on the object that puts them under pressure, so the weight of the car, the power of the engine, and the center of gravity of the person are all factors that will affect the grip of the tire! If you simply rely on weight, the most direct external force, to squeeze the tire, the grip you can get is limited. Because motorcycles will generate centrifugal force when riding in a curve, the “stickiness” of the tire alone cannot produce enough grip. The power generated by the engine is the main source of grip for the rear wheels!
High-performance tires = safety?
I believe that many people have the stereotype of “high-performance tires = safety”. After reading the above, everyone can also know that the tires’ grip is produced by the deformation of the tread and the contact with the road surface. So if you want to say that the grip of the tire depends on whether it is sticky or not, the correct way to say should be whether the tire is soft or not. So here comes the problem: soft tires grind fast but wear-resistant tires seem to be unsafe. Many people who have this idea would rather sacrifice their pockets for safety, and take the risk that they might run out of tires halfway through a long trip to use high-performance tires, but is this really safe?
However, each tire has different properties, softness, and difficulty in squeezing deformation, so this time it depends on your riding habits and vehicle type to choose the tire you need. Many good friends say that it is safer to replace the tires with better tires. Isn’t that the goal to go straight to the top tires? This is wrong. Tire selection is not like this, but what is the difference between high-performance tires and ordinary street tires? In short, it is the “difficulty in getting into work ” and the “difference of limits”.
- Difficulty in getting into work
Many people know something about “tires warming”, but the purpose is to get tires into working condition, which is also called “wake up”. The high-end performance tires are made of soft material and can easily enter working conditions. However, the general street tire material is hard, so it will naturally take more time to get it into working condition, but if the vehicle is heavier, the tire can enter the working condition very quickly (because of the heavy burden on the tire). The grip provided by the tires in working conditions is actually very stable and powerful. Unless it exceeds the limit value that the tire can withstand, it will actually be enough on ordinary roads!
- Difference of limits
Soft tires represent the ability to deform with lighter force. The biggest difference lies in the “deformability at high speeds”. Because of the material and the manufacturer’s special weaving method, high-performance tires can maintain sufficient deformation ability even at high engine speeds. It is difficult for ordinary street tires to achieve this effect. However, we usually face low-to-medium-speed compound corners in our daily leisure running, and the speed section of these corners may be more than enough for ordinary street tires.
High speed can indeed get faster acceleration after exiting a corner, so it is recommended to retreat into a low gear before the corner to obtain a higher speed and faster exit response. It also destroys the stability in the corner. The time to finish this mountain road is not slow, but I always feel that my fluency is not enough.