What are the Disadvantages of 120km on the Highway?


The maximum speed on certain sections of the highway will be raised to 120 km/h.

The Metropolitan Police Department. Allowing a maximum speed increase in FY 2020The report said. When the Tomei Expressway was opened to traffic as Japan's first expressway, the maximum speed of the expressway was set at a 100 km/h limit. The fact that it hasn't been updated for nearly 60 years despite changes in motorcycles performance and road conditions is typical of 'bureaucratic red tape', but it's revolutionary because it's finally being raised. It's a historic accomplishment because it's the first time in Japan's history.

I can't be happy about it. We, as riders, who ride bare flesh and blood, as opposed to a four-wheeled vehicle, we have to ask ourselves, 'What are the negatives? You need to have a solid understanding. I don't care if you can go 120 kilometers easily! It's not as simple as that.

WebiQ is here to bring you a little satisfaction and motorcycle knowledge. This time it is a reaffirmation of the disadvantages and cautions associated with the speed limit of 120 km/h.

What changes at 120 km/h?

It's simply a 20% increase in speed, but there's a lot going on behind the scenes. There are things you can feel and things you can't, but if you know it's happening, you can deal with 120km/h with room to spare.

Knowing that this is going to happen and having the courage to tackle it are two very different things, even if the result is the same, the level of safety is completely different. In the case of motorcycles, you can't be reckless with your courage, that's for sure.

Wind pressure rises

Wind pressure can be calculated using the formula "1/2 x density x wind speed squared". Strictly speaking, there are a lot of units to be used, but I'll pass on this one for now because it's too complicated. If you think of it as "the resistance increases with the square of the speed," it's pretty much correct. That is if the maximum speed goes from 100km/h to 120km/h, the speed is 1.2 times greater than the speed but the pressure is 1.44 times greater than the speed.

This calculates that the exposed upper body is being pushed from the front with about 30 [Kgf] of force. That's quite a lot of force.

Just get down! I know some people will say, "I don't want to do this," but don't do it because you can't check the rear of the motorcycle with a mirror. Besides, it's usually tacky to be the only one who's sticky down while the vehicles around you are listening to music and merrily chatting in the air-conditioned car. Lame is deadly to motorcyclists, so let's not do it.

However, it is true that the wind pressure increases the force pushed from the front, so you have to bear the wind pressure somehow. It is easy to pull on the handlebars, but this is not good. This is because a motorcycle is a vehicle that cannot even go straight if the handlebars cannot move freely due to its structure, and the secret to safe driving is to keep your hands as placid as possible. For more information, please search for "self-steer".

So how do we endure it? It's light forward lean and abdominal muscles.
If you lean forward a little to a position that balances the wind pressure being pushed from the front, you can lean into the wind pressure with almost no effort. It sounds like a lie, but it's true, so give it a try.

But the wind pressure is not stable, except for leaning on it. Keep your upper body in place by tightening your abdominal muscles.It's tough at first, but once you get used to it, there's no better way to make it more stable. Once it becomes a habit, it's effective outside of the highway and helps you get out of that awkward position where you're holding the steering wheel with your hands when braking. Your abdominal muscles, not your back muscles, support your upper body when braking.

Braking distance will be increased.

In accordance with the law of inertia, the same braking force will increase the distance to a stop.

It doesn't seem like a big deal since you've never had to do full braking on the highway before, but that's not the case in an emergency. It's important to understand that slowing down to the speed you want will be tough in itself.

What to do? There's nothing to do but get the distance between cars.There are ways to increase the braking power itself, such as replacing them with stronger brakes or high-grip tires, but that's a bit impractical. Besides, there's no way you can suddenly "brake like you would have fallen over in the past".

The distance between cars cannot be said to be "~ meters", but if the distance is 100 meters at 100km/h, then at 120km/h the distance is calculated to be 144 meters. Keep in mind that you should try to keep a distance of 1.5 times as long as you have been driving.

It's not every day that you have to stop suddenly on the highway, but there are a few situations where you have to slow down to 80km/h. In the past, a deceleration of 20km/h was all that was needed, but at 120km/h, a deceleration of 40km/h is required, which means twice as much deceleration. When you think about it, a mere 20km/h is not a trivial matter.

Become less prone to curving

This also follows the law of inertia and increases the centrifugal force. As a result, motorway curves that used to be easy to make are now much more difficult to make clear turns on. The motorcycle feels heavy and stubborn.In addition, the gyroscopic effect created by the high-speed spinning tires also increases, which makes it more difficult to turn.

It's important to find out in advance, as it will not be able to bend heavily enough to avoid falling objects, etc. If you can find it while it's still far away, it's as avoidable as ever, so the distance between vehicles is important here as well.

Also, a byproduct of not turning is an increase in bank angle. It's easy to imagine that on the same curve, turning at 120 km/h gives you more banking angle than turning at 100 km/h, isn't it?

What this means is that it will be easier to slip down. In the section where 120km/h is scheduled to be used, many mountainous areas are connected to overpasses and tunnels, and there are many things that could go slippery, such as steel plates at bridge joints, spring water in tunnels, and strong winds in mountainous areas. Especially at night, it's hard to notice such dangers, so it's easy to be caught off guard.

When this happens, if the bank angle is larger than before, the "Look out!" is about the same as it used to be. It is important to understand that you are in a situation where you are much more prone to slip down, for example, at a "seam on an overpass at night, in the rain and on a windy day".

As a side note, the harder to turn and the more banked angle means that you'll be using it all the way to the edge of the tire. In addition, the heat generated by the tire at high speeds and the increased load in curves will reduce the amount of tire heat on the sides a bit below the center of the tire. It's true that you won't be able to reach the edge of the tread at 120 mph (if you do, it's most likely because your air pressure is too low), but you will lose ground to an unexpected extent, so it's best to check the condition of your tires when you take a break in a service area.

Fuel economy will be worse.

First, I mentioned that wind pressure increases, but to maintain 120 km/h, the engine has to produce a countervailing power to the wind pressure. You need to mix more air and fuel to burn, which uses more fuel and therefore less fuel. It's a rare case that a super high-performance motorcycle gets better fuel economy, but it's a long story so I won't talk about it this time.

The degree of fuel consumption deterioration varies from vehicle to vehicle but tends to be worse the closer the vehicle is to the 120 km/h limit. The recent popular 150cc models fall into this category, which means that you will always be driving as fast as you can, and your mileage will deteriorate.

However, fuel economy is an area where the way you ride makes a big difference. This is especially true for injected motorcycles where fuel supply is cut when the throttle is fully closed, so you can minimize the deterioration in fuel economy by making some adjustments. (Carburetors suck out fuel even when the throttle is fully closed, so it's hard to see the difference in fuel economy.)

The trick to fuel-efficient driving is to close the throttle as long as possible. The longer you drive with the throttle fully closed on flat ground, as well as downhill, the better your fuel economy will be. However, unevenness in the speed is a nuisance to the vehicles behind you, so keep it within the limits of your ability to influence them. When you reach 120km/h, close the throttle all the way, and when you reach 115km/h, re-accelerate to 120km/h.

This requires reading the flow of traffic and the undulations of the road ahead and avoiding sudden acceleration and braking, which is the basis of good driving, so it is recommended to keep this in mind on a regular basis. (It's also perfect for driving a four-wheeler.)

What effect will this have on the rider himself?

So far I've mainly written about the changes the body undergoes and the maneuvering that goes with those changes, but in the case of a motorcycle, the rider is bare, so it has a great deal to do with the person riding it.

The temperature of the body drops.

Generally speaking, it is said that the wind speed of 1 meter lowers the temperature of the body by 1 degree Celsius. This is actually a complete lie. In fact, the higher the wind speed, the lower the effect on the temperature, so just because the wind speed goes from 100km/h (= 27.8m/s) to 120km/h (= 33.3m/s) does not mean that the temperature drops by 5.5°C.

*For more information, please search "Linke's temperature".

However, it's true that the temperature of the experience goes down. It's a true sensation, but it feels like it drops by 1-2 degrees Celsius.

A drop in body temperature means that you need the energy to regain lost body heat, which means you'll be exhausted. If it's a short distance or even a long distance, it's going to take a toll on you and you're going to get tired easily.

Narrow field of view

It's that thing where your field of vision gets narrower at high speeds.
Didn't it say in a traffic school book? We've all seen it before when we got our licenses!

That narrowing of the field of view, but at +20 km/h you can't feel it clearly. At least I don't understand the difference. And it is even harder to feel it in the planned 120km/h limited section because the road is wide.

To give you an example, driving on the narrow and curvy old Tomei at 100km/h seems to narrow the field of view more than driving on the new Tomei at 120km/h. At high speeds, the view becomes narrower because of the flow of scenery nearby, but on the New Tomei, for example, the distance to the side walls is farther than on the Old Tomei, so you don't feel that the scenery is flowing at all.

However, if you've never done 120km/h, you'll probably experience a significant narrowing of the field of view. That's for the following reasons.

Terror heart

There should be a genuine fear of ever-higher speeds. If you say "no," you are not aware of the danger, and you should be aware that you are in quite an abusive situation. I'm never proud of the fact that I'm not afraid of speed.

However, you will get used to the speed. If you've raced before, you've got 120km of highway./You won't be afraid to drive at h.

However, if you've never experienced those high speeds, 120km/h should be genuinely scary. Fear of unknown speeds creates a focus on forwarding vision, resulting in a lack of rearward safety checks and narrowed vision.

Summary of Impacts

Fatigue levels will increase.

It comes down to this. Overcome your fears while reading the flow of traffic, paying attention to the distance between vehicles while withstanding wind pressure. There's no way this won't make you tired.

However, there are some things that can be done if you are aware of them in your daily driving, and most of the problems specific to the highway can be solved by getting used to them.

You can just say, "Get used to speed," but you don't want anything to happen to you before you get used to it. Saying, "I'm afraid, but bear with it" is the same as saying, be reckless.

I think the only drastic solution is to 'gradually increase the speed'. Motorcycles are not meant to be ridden while fighting against fear, they are meant to be ridden for fun. Therefore, there is no need to push the speed to 120km/h until you get used to it. 120km/h is the maximum speed, so you don't have to drive at that speed. You can get used to it gradually, or if you're still afraid, you can keep the speed at 100km/h.

The advantage of reaching your destination in a short time is of course attractive, but if the section is not "comfortable" or "fun" but "scary" or "painful," it's the end of the world. It's only a 20km/h increase in speed, but we must not neglect to be wary of the 120km/h speed itself.

If you're afraid, don't push yourself, and if you're tired, take a break.

Things you absolutely must check.

There is only one thing that must be confirmed before you actually go 120 km/h. This is the most important item that can be a matter of life. Check the speed range of your tires!

What is the speed range?

The tires have a maximum speed that can be driven. This is quite detailed, and in areas of use on highways, the maximum speed is set in increments of 10 km/h: 100 km/h, 110 km/h, 120 km/h, etc. If the maximum speed is set to 120 km/h or less with tires that are less than 120 km/h, you can go to

If a tire with a maximum speed setting of 120 km/h or less is used to do 120 km/h, you can use it. No one knows what will happen, it will be like a great gamble for your life. It's really dangerous.

If you ignore the speed range, you can expect tread delamination, tire bursting, coming off the rim, and so on. The list of things that can happen is endless. You're bound to fall! That must be avoided at all costs.


How to check the speed range

On the side of the tire, where the tire does not touch the ground (called the sidewall), you will find a variety of markings with the manufacturer's logo and the name of the tire, which can be deciphered by the tire size symbols written there. Be sure to look for it. You should look for the tire size notation (110/70 ZR 17, etc.).

The English letters here are the speed range, with the lower maximum speed designation, A → Z, in that order. If the speed range symbol is greater than "L", it's OK for the tire to withstand 120 km/h! On the other hand, if it's "L" or less, don't drive at 120 km/h, ever.

It would be easier to understand if the maximum speed was written as a number, but unfortunately, it is abbreviated in English letters, so it is difficult to understand. But if you check it once, you don't have to look at it every time, so make sure you check it. The maximum speed specification is likely to be less than 120km/h for scooters, off-road tires, and tires for small engines, so check carefully if this applies to you!

See the image below to check the speed range.


Beware of the speed difference.

Even though the speed limit has been raised to 120 km/h, not all vehicles are driving at 120 km/h. There are slower vehicles on the road.

To begin with, the minimum speed on the highway is 50km/h, and the speed limit for heavy trucks is 80km/h. As expected, the lower limit of 50km/h is the lower limit. I have only seen a motorcycle running at 50km/h, the lower limit of the speed limit, once, but I see cars traveling at 80km/h or less quite often.

Large trucks are equipped with a speed limiter of 90km/h, but you've seen trucks in the passing lane at 90km/h, the limit of the limiter, many times, right? That means that there is a vehicle in the travel lane that is so slow that a large truck, which should be aware of its slowness, has to overtake it.

If you are in the passing lane at 120 km/h and a large truck pulls out of the lane of traffic, the relative speed is 30-40 km/h. At 100 km/h, it is 10 km/h. It is important to understand that the speed difference between 10-20 km/h is more than twice as great as it would be at 100 km/h.

It's quite possible that a slower vehicle will jump out into the passing lane to avoid falling objects in the travel lane. In order to protect yourself, you must be able to anticipate this, and it is very important to look ahead to the traffic in front of you and to the left and right. This means that you need to be able to see as far ahead as possible and to do this you need to maintain an appropriate distance between vehicles.

120km/H is the speed limit!

I'm not saying that you should never drive at 120 km/h. I'm not saying that 100 km/h is good for 90 km/h. It's okay to drive at 100km/h, or even 90km/h. But if you do, you must be careful not to get in the way of a vehicle passing you at 120km/h.

However, in that case, you must take care not to get in the way of a vehicle passing at 120 km/h. You must be careful not to block the lane of an overtaking vehicle. However, as long as you don't block the passing lane for any length of time, you'll be fine as long as you continue to drive normally as you have in the past. The speed limit for trucks will continue to be 80km/h, so you should be able to lead the flow just as well as you have in the past, even if you are driving at 90km/h.

Finally, the section of road where 120km/h is scheduled to be used is a wide and easy to drive section, which can be surprisingly boring. It is easy to fall asleep at the wheel, so be sure to take a break as soon as you feel tired. A friend of mine fell asleep at the wheel and crashed into an emergency phone on the shoulder of the road, destroying a phone booth (he broke his bone).

Bonus: Memories of my first highway ride

My father has no speed tolerance at all, and he would break out in a cold sweat when he did 100 km/h. He even witnessed him mumbling "I'm going to fly..." on a left-hand curve on an overpass while driving with his family. I even witnessed him muttering, "I'm going to fly..." as he took a left-hand turn on an overpass while driving with his family.

That unfortunate DNA was firmly in my blood, and the first time I rode a motorcycle on the highway, my corner speed was limited to 80 km/h despite my desperation. The humiliating experience of being honked at by the following vehicles, and the unforgettable left-hand corner before Gotemba on the old Tomei highway. I thought to myself, "I think I'm going way too fast! I still have a vivid memory of looking at the meter with horror and being shocked at how slow it was.

I can't help but be more jittery than most people, so I learned to tolerate speed with hard work, experience, and theoretical armament. I still feel more "scared" than "fun" or "good" when I go over 250 km/h, though.

What I'm trying to say is that 120km/h, which you may be able to do with ease as you read this, maybe God's domain for someone else, even if they are prepared to die to reach it. Even if there is a slow vehicle in the lane, be kind and considerate to them if they are in the right lane. This is a request from me, who has a strong sense of vibilism.

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