The most important thing when riding a motorcycle is to avoid accidents on public roads and minimize them as much as possible. To achieve this, it's essential to know your own riding skill level and understand the dynamic characteristics of your motorcycle.
This "Assessing Riding Skills Through Images" project, published irregularly, aims to interpret and explain a rider's riding characteristics from a single riding image. The image featured today is the one below. What can you infer from it?
Cornering images are the most likely to reveal riding characteristics. I always pay attention to the "Lean Angle," "Front Fork Stroke," and "Front Wheel Direction." Just by observing these three elements, I can determine a rider's riding style and skill level, so I don't pay particular attention to rider's physical appearance, such as riding form or seating position.
■ バンク角 / Lean Angle
・ 充分な角度までバンクさせられており、問題はありません ・ There's sufficient lean angle, so there's no problem.
■ ストローク量 / Stroke
・ さほど沈み込んでいません。この事から、コーナリング初期には前輪に掛かっていた筈の荷重は抜けており、前輪のグリップ力は低下している事が判ります ・There's not much sagging. This indicates that the weight that would have been on the front wheel at the beginning of the corner has been released, reducing the front wheel's grip.
■ 前輪の向き / Front Wheel Direction
・ コーナーの出口がライダーの視線の方向だとすれば、前輪の向きと出口方向との違いが大きく、アクセルを開けていける状態ではありません ・If the rider is looking toward the corner exit, there's a large difference between the front wheel's direction and the exit direction, preventing them from opening the throttle. 以上の事から、この人にはライディングスキルを向上させられる幅が大きい事が判ります。 タイヤのグリップを高く保ち続けて、安全にコーナリングを行なうには、コーナリング前半は前輪に荷重を掛け続けて、自然にフロントタイヤの向きが変わるのを待ち、その後、コーナリング後半は意識してアクセルを開けていく様にする事が勧められます。 そして、画像の様に前輪の向きが充分に変わらない内からコーナーの出口方向を見るのも決して悪くはありませんが、それは、野球やサッカーなどボールを使う競技で、ボールに打撃を与える瞬間以前に目を逸らしている様なもので、正確なコントロール技術は得られないでしょう。自然に前輪の向きが変わる操作を意識して行ない、アクセルを開ける直前まで旋回から意識と視線を外さない事をお勧めします。
The above indicates that this rider has significant room for improvement in their riding skills. To maintain high tire grip and corner safely, it's recommended that they keep weight on the front wheel during the first half of the corner, wait for the front tire to change direction naturally, and then consciously open the throttle during the second half of the corner. And, as in the image, it's not a bad idea to look in the direction of the corner exit before the front wheels have fully changed direction, but that's like looking away before you hit the ball in a ball sport like baseball or soccer, and you won't gain accurate control. I recommend being conscious of the way the front wheels naturally change direction, and not taking your eyes off the turn until just before you open the throttle.
Riding skill is the ability to use the characteristics of your motorcycle comfortably and efficiently. Being fast or flashy does not necessarily mean you have high skill. In fact, even someone who can ride fast does not necessarily have high skill, and there are many skilled riders who don't ride fast. Furthermore, I believe that the key to honing and improving your riding skills is to listen to your motorcycle, understand its characteristics, and know your own and your motorcycle's limits.
This book, "Examining Riding Skills through Images," is intended to be a reference for anyone wishing to "improve their riding skills." It shares the experience and knowledge I have gained from observing the riding of many people over many years, as well as my own extensive research and practice in improving my skills, so I hope you will find it useful.
If you were to ask, "What do you need to continue your activities?", many people would probably answer "money," "number of participants," or "good equipment." However, I would answer "people."
Since the company's founding in 1991, I've had little interest in money. We weren't profit-making organizations, nor did we divert our income. We simply deposited our money in a dedicated bank account. However, since 1995, the number of events we held increased, and proper management became necessary. That's when Ms. S and Ms. H from Osaka offered to handle the accounting. Ms. S handled the accounting for two years from 1998, and Ms. H handled the accounting for two years from 2000. Thanks to their help, we've been able to successfully hold over 40 events a year.
And then, from 2002, Mr. O, who now lives in Paraguay, took over the accounting for over 10 years, building an accounting system tailored to GRA's structure. He created an accounting worksheet in Excel for each event, with each event and item categorized, to make it easier to understand the cash receipts and payments for each event and to input data. This detailed system organized by event allowed us to operate with peace of mind, and it remains an important system for us today.
In 2016, Mr. O from Osaka took over the accounting duties. Not only is he skilled in accounting, but he is also a talented and passionate person who continues to support GRA's activities in many ways.
In 1998, when the Internet was gradually becoming popular, Mr. U from Hyogo asked me, "Why don't you make a website?" At the time, websites were still in their infancy, but he built a website for GRA all by himself. Thanks to him, we were able to lay the foundation for expanding our website-based advertising activities.
It was Ms. K from Osaka who helped us turn this fledgling website into a fully functional site, complete with event announcements and various post-event release pages. She was a great contributor, creating numerous pages directly in HTML, without using website creation software, allowing for more precise page layout and color scheme adjustments. Thanks to her work, we were able to create a fully functional website, complete with event schedules, event reports, course maps, and results.
It was Mr. T from Osaka who rebuilt the website into its current format, which allows for even more detailed information to be disseminated. Thanks to his efforts since 2010 to build the website, we have now reached the current size of over 3,000 pages. His contribution to making it possible to provide GRA with diverse content and detailed information is immeasurable. The time he has spent must have amounted to several hundred hours. We are truly grateful for his help.
In 2004, Mr. M from Kanagawa suggested we become an NPO. At the time, we were considering changing from a voluntary association with little social responsibility to a corporate organization with a strong social credibility in order to achieve our goals of raising rider awareness and social recognition. His words were a lifesaver. Mr. M only attended three events, but I believe he wanted to support us in his own way. Just a few months after I agreed to his proposal, I received an envelope from him containing the necessary application documents and a set of application procedure guides for becoming an NPO. As long as there were no problems with the information provided, all that was left to do was stamp the documents and submit them. Thanks to him, we are still able to continue our social contribution activities as an NPO.
Mr. K from Osaka was the one who checked the documents prepared by Mr. M and took it upon himself to handle the legal matters, which I had no experience in. He rarely attended GRA events and was not very noticeable to me, but when he noticed the move to incorporate as an NPO, he offered to handle the legal matters, which he used his experience in, and has since been in charge of important management tasks for the NPO.
The "Office Staff" are special people who are different from many other supporters. While other supporters provide support at their own discretion and in their free time, the "Office Staff" come to a designated activity base every week to handle various administrative tasks and work several hours without pay. Among them, Ms. T and Mr. O from Osaka are particularly special.
In 1998, when the number of events increased and the amount of administrative work grew, Ms. T began attending "administrative meetings," which we held once or twice a week to handle administrative tasks. She spent more than three hours a day, almost every week, for approximately 17 years. She has devoted well over 2,000 hours to administrative tasks. What's even more important is her continued belief in GRA's goals and ideals and her commitment to working with us for so long. It's thanks to her contributions that GRA has been able to continue its activities. Without her contributions, GRA would undoubtedly not exist today, and she is an important person for whom we owe our deepest gratitude. Thank you very much. O君も、Tさんと同じく1998年から、週1日以上、毎週欠かさず活動拠点に来てくれて、事務処理を行なう支援を 10年以上してくれました。彼も、GRAの掲げている目標を深く理解してくれて、積極的に参加してくれた方で、他にも 広報や経理などの業務も担当してくれるなど、GRAの活動には欠かせない大切な人です。
Since 1998, Mr. O has come to our base at least once a week without fail, helping with administrative tasks, for over 10 years. He also deeply understands and supports GRA's goals, and is an important person who is indispensable to GRA's activities, taking care of public relations, accounting, and other tasks.
In addition to Ms. T and Mr. O, introduced above, I will not forget the other people who participated in "administrative meetings" and handled a huge variety of tasks. I would like to express my gratitude once again.
For me, the most important thing in our activities is to adhere to the goals and principles we had when we were founded. For that reason, even if there were times when we stopped holding flashy events and our activities seemed to have changed significantly, the people who shared our goals and continued to walk alongside us over the years are our most valuable assets, and they are the biggest reason why GRA has been able to continue its activities for so many years.
In the past, we have changed the format of our activities several times, under the guise of a "de-pick" plan. At times, we stopped holding events for several years, and as a result, many people who had participated in GRA because they admired the flashy running events lost interest in it. In fact, at the beginning of an information session on the "de-pick" plan held in January 2001, someone raised their voice in anger, asking, "Why did the secretariat just stop holding events on their own?" Despite having received a detailed outline of the plan in the mail in advance, he failed to inquire about the administrative workload beyond the event itself. Furthermore, he loudly criticized the administrative office's activities in front of Ms. T and Mr. O, who had made significant contributions as "administrative staff."
At the time, I didn't point out or argue with him because his comments were unexpected, but later I became convinced that his actions made the "Evolving Plan" a necessity. The "Evolving Plan" was necessary precisely because there were people who not only disregarded GRA's stated goals, but also prioritized their own enjoyment by attending events, ignoring the people who provided so much support to continue the organization. Therefore, with each "Evolving Plan," the number of participants in running events decreased. However, we continue to be blessed with people who sympathize with our philosophy and continue to support us to this day. And I believe that as long as we continue our activities with the same philosophy, there will be more people like that around the world.
Grass spreads its roots in the joints of the paved road surface, eroding the asphalt over time, and in some severe places the asphalt pavement has turned back into soil. Therefore, we are working to remove the underground stems as much as possible. This will prevent the grass from regrowing for a while.
Traffic Park is located on a riverbed, so the accumulation of sediment is serious around the periphery of the park, especially at the four corners. However, the cleaning area this time was in the middle, so there was not much concern about sediment accumulation.
Thus, the cleaning work started at 5am, and by around 9am, we were able to complete almost all of the planned area without being significantly affected by the midsummer sun.
Looking back at the northwestern outer path area of the park, where we worked in June and July, under the clear skies, it feels good to see that the road surface seems to be happy as well.
The next cleaning planned area will be the outer perimeter road at the upper left of the course map. We also want to clean the roads to improve safety for people using the park.
This is an image I don't remember taking. It's an image of my usual cluttered room, and the focus and composition are poor, but there's something about it that's intriguing. Perhaps it's a message from me, who lives in a parallel world.
GRAは、誰でも自由な意思と自由な方法で運営にも参加できるのが最大の特徴です。今回は、企画や機材などの支援で参加された方々を紹介します。 GRA's biggest feature is that anyone can freely participate in its management. This time, we will introduce the people who supported us with planning and equipment.
We have received various proposals from several people regarding the operation plan. The most memorable person among them was Mr. H from Shizuoka. He proposed a well-thought-out plan that he had devised on his own. He put together a proposal document that was several pages long. Furthermore, a few years later, he even offered to give us his motorcycle that he no longer rides. We are deeply grateful for his support in the operation of GRA.
Iwas even more surprised by Ms. Y's initiative from Hyogo. In 1993, he asked us if we could make a collection of impressions, and we simply replied, "Yes, it would be fine." However, he created a collection that far exceeded our expectations. He asked participants of a special event called the "Gymkhana Party," which was held twice a year, to write their impressions, and later received and edited the impressions, added illustrations and photos, and compiled them into a fine collection of impressions, and delivered the printed data to the secretariat. And over the course of seven years, he delivered the joyful voices of the people who participated in the Gymkhana Party a total of 14 times. Thanks to you, many people are still viewing our website.
Furthermore, Ms. O from Kyoto provided us with great support in the area of art. He proposed a plan for an information pamphlet for the Gymkhana Party, and created a pamphlet that looked like a party, even including illustrations that he created himself. He then took it upon himself to create a magnificent banner for the Gymkhana Grand Prix, over 4m wide. He also did a great job as an art designer, creating banners for the sponsoring companies. Thank you very much. I still treasure the banner that he created for us, featuring an illustration of "Gymkhana Boy."
The first person to surprise me with the arrangement of large equipment was Mr. Y from Hyogo. In 1991, when we held the first Gymkhana Party, he arranged and delivered the PA equipment, which is essential for large events. At that time, I did not realize the importance of PA equipment, and just decided to hold a party event, but thanks to him, it became a very exciting event. After that, at the Gymkhana Party, which was held twice a year, Mr. Y continued to arrange PA equipment that was gradually upgraded, and we were always able to fill the event with a fun atmosphere. Thank you very much.
Mr. N from Osaka made and provided special equipment for the Gymkhana Party. In 1992, he delivered and set up the so-called Christmas tree, which is used to display the start signal for races, to the event venue himself. I was surprised because I hadn't expected this, but thanks to you, it helped us to get the event off to a smooth start and liven up the atmosphere. Thank you very much.
また、PC関連機材の提供して下さった方も多くいらっしゃいますが、その中でも、兵庫の N君の事は決して忘れられません。彼は、走行系イベントへの参加回数は 3回と少ないのですが、タイム集計用の PC と プリンターなどの 機器を提供して下さったのです。その際、必要な機材を分かり易く綺麗なパックに収納して、必要な時に誰でも利用し易い状態で 贈呈して下さった事はよく覚えています。その他にも、「公式Webサイトの 啓発コラム用に使って下さい」として、社会問題を題材にした画像を自ら撮影して、それを送付して下さった等、GRAが取り組んでいる社会的な課題にも真摯に向き合いながら、20年以上に亘って支援をして下さっている方です。ありがとうございます。どうぞ、これからも宜しくお願いします。
Iwill never forget Mr. N from Hyogo. Although he has only participated in three running events, he provided us with equipment such as a PC for tallying times and a printer. He has also taken photos of social issues himself and sent them to us, asking us to use them for the awareness column on our official website. He has supported GRA for over 20 years, sincerely addressing the social issues that GRA is working on. Thank you very much. I look forward to your continued support.
And Mr. Y from Tokyo donated a desktop PC he built himself, asking us to use it as a PC for the secretariat. Thank you very much. Although Mr. Y has never participated in an event, he has been supporting GRA's activities for many years, including converting about 200 analog videos into digital format and creating many illustrations required for explanatory articles using a PC. Thank you very much. We look forward to your continued support.
Iwill also never forget that the Aichi Prefecture organizer, TSRA, donated a homemade "start gate" to be placed at the starting point in 1991 to coincide with the first "Gymkhana Party." Although they did not contact us in advance, they decorated it with beautiful colors and livened up the atmosphere of the party, which left a strong impression on me. After that, we used it as an important production equipment for many years. Thank you very much.
And it was Mr. S from Osaka who purchased 40 pylons needed for the event and continued to carry them to the event venue. Thank you very much. We were very grateful for your help.
Mr. M from Shizuoka donated a PA set with a CD changer, and also provided us with a lot of necessary software and information for the PC, which has been a great help to the operation of the secretariat. Thank you very much.
In addition, Mr. I from Osaka arranged and provided various equipment that may be needed for events, and Mr. K from Shizuoka donated a converter to extract AC100V from a car battery for the PA equipment. We have received support from so many people that it is impossible to introduce them all here. Once again, we would like to express our gratitude. Thank you very much.
As mentioned above, GRA has continued its activities thanks to the support of people all over Japan. In the next and final installment, we will introduce the most important and indispensable "secretariat staff" who have continued to support GRA's activities from the ground up.
The swallow couple that arrived in May this year renovated the abandoned house (nest), gave birth to a baby, and let it leave the nest safely at the end of June. Then, at the beginning of July, a new couple arrived to replace them. So, if all goes well, we should soon be hearing the voices of healthy babies.
However, there is one thing that worries me. It's the local gang of sparrows. They make short, threatening sounds and attack if they get the chance. I know that last year, the house that the swallows that arrived were renovating was cruelly destroyed, and only one male swallow was left, singing all summer.
Of course, the gang is coming again this year, but the May couple was able to drive them away skillfully. However, the July couple, perhaps because they are newlyweds, seem a little confused about how to deal with the approaching sparrows.
But I'm sure they'll be fine. Sometimes during the night, the adult bird's voice can be heard from inside the nest. This is proof that the adult bird is definitely still incubating eggs in the nest. In the near future, the voices of the babies will be heard early in the morning. (The image shows him, judging from the shape of his tail feathers.)
Clouds continued to spread across the sky from the morning, which helped to reduce physical exhaustion, and the continuous rain over the past few days made it easy to remove the thick layer of dirt and sand that had built up on the road surface .
Even so, the power of plants was on full display this time as well. There were many areas of the road surface where the asphalt had been eroded over the years and turned into soil. In places like this, it is necessary to remove not only the leaves above the soil, but also as many of the underground stems that run in all directions in the soil as possible to prevent the plants from regenerating, which is quite a lot of work.
The other day, TANITA told me that the "internal age" had suddenly increased. I was shocked.
But the next day, it said it was 54, just like before. It's good to complain.
Either way, the results are calculated through programmed processing using the data you entered and the measured data, so it's an important indicator of your health. I hope you'll continue to support TANITA.
GRA began its activities in the 1990s, the age of analogue. Thanks to the support of many people in digitising the records and materials from that time, we are still able to carry out a wide range of activities today.
『 データ処理 / Data Processing 』
1990年代は、開催された競技イベントで、印字されたリザルトが配布される事は無かった時代でしたが、京都の S君がその常識を大きく変えてくれたのです。1992年、S君はは、独自に制作した集計ソフトと 自身の PC とプリンターを持ち込んで、見事、立派なリザルトを作成してくれて、配布する事が出来たのです。当時、PCと言えば デスクトップ型が殆どで、小型のプリンターも無く、表計算ソフト Excel 3.0 さえ普及が始まったばかりの頃でしたが、S君のお蔭で、イベントの最後は、綺麗なリザルトを参加者全員に配布出来た時は大きな喜びでした。ありがとうございました。あなたの大きな支援のお蔭で、GRAは活動の質を高めていく事が出来ました。
In the 1990s, printed results were never distributed at competitive events, but Mr. S changed that perception. In 1992, Mr. S brought his own calculation software, PC, and printer, and created and distributed beautiful results. At the time, most PCs were desktop computers, there were no small printers, and even spreadsheet software had only just started to become popular, but thanks to Mr. S, we were very happy when we were able to distribute beautiful results to all the participants at the end of the event. Thank you very much. Thanks to your great support, GRA has been able to improve the quality of its activities.
Following in Mr. S's footsteps, Mr. H from Osaka and Mr. K from Hyogo also began to use their own laptops, small printers, and spreadsheet software that they had set up themselves to calculate times. Thanks to them, we were able to distribute handwritten results at most of the events we held, and the quality of the events improved significantly. Thank you very much. They have established a platform that allows anyone to compile times, even without specialist knowledge, and this has undoubtedly enriched the results and encouraged many participants.
In 2010, GRA decided to shift to disseminating information worldwide via the Internet, and the thing we needed the most support from many people was to digitize over 300 "results." Moreover, the results required nearly 10 input items for each participant, such as "name" and "vehicle name," and we had to do this for nearly 100 participants, and then convert it into HTML for posting on the website, which was a huge process. At this time, Mr. T from Kyoto played the most important role. He created a spreadsheet based on a spreadsheet software that allows the inputter to easily input the necessary items with fewer errors, and also incorporated a program to convert the input data into HTML. Thank you very much. Thanks to him, the results of past events can be widely shared with people all over the world.
Nearly 15 people volunteered to manually input over 300 results again. At the time, there were many restrictions on PCs and communication environments, so we mailed the Excel input sheet that Mr. T created to those who volunteered together with the results to be input. Then, we had them return the sheet after inputting the data, which is a time-consuming process that would be unthinkable today, but in a short period of 7 to 8 months, we were able to digitize almost all of the results. Thank you very much. Thanks to him, the most important information about competitive events is being delivered to many people.
In addition, Mr. Y from Tokyo was in charge of data processing of the video data. Since digital video cameras only started to become widespread in the 2000s, the nearly 200 videos shot up until 2010 were in analog format, and they needed to be digitized in order to be made available on the Internet. Mr. Y was the one who handled the data processing alone. Although he had never attended a GRA event, he was a great help to us by taking on this time-consuming task. Thanks to him, we have been able to widely spread awareness of GRA's activities to people all over the world. Thank you very much.
Iwill also never forget the support that Mr. K gave us in the participant data management system. Since we started our activities in 1991, we had continued to manage the data using a relational data system that we had set up ourselves, but in 2010, there was a high possibility that we would not be able to keep up with changes in the OS, so we tried to switch to a system using ACCESS. At that time, Mr. K from Shizuoka reconfigured the system for ACCESS. Thank you very much.
We are grateful for the support from people across Japan, which has enabled GRA to widely share a vast amount of information and continue our awareness activities. In the next issue, we plan to introduce two people who strongly supported our transition to an NPO.
I weigh myself once a day with a TANITA scale. In addition to my weight, I check my body fat percentage, muscle mass, etc. I weighed myself again today and felt down. There were no problems with my weight or body fat, as always. But the "internal age" shown at the end was 55. Yes, I'm not complaining because I'm younger than my actual age, but... Until yesterday, it had been 54 all this time.
Yesterday, I had an attack of atrial fibrillation (palpitations). Apart from feeling very sick, the most frightening thing is that blood clots that are easily created during an attack can lead to cerebral infarction or myocardial infarction. So, once I have confirmed the attack with a diagnostic machine, I go to bed immediately. I rested from 1pm, and yesterday it subsided after 9 hours.
During that time, my heart rate continued to record more than 150 beats per minute. However, since my heart was not behaving normally, my blood pressure dropped significantly, to about half of normal levels this time, and I even felt dizzy.
今は、発作が治まり、まるで、何も無かった様な気分ですが、行動を控えています。なぜなら、発作の間、体中の細胞に老廃物が溜まり続けていたからです。心拍と血圧が戻ったとしても、脳や末端組織の環境は元に戻っていないからです。 Now that the attack has subsided, I feel as if nothing had happened, but I am refraining from action. This is because waste products continued to accumulate in the cells throughout my body during the attack. Even if my heart rate and blood pressure return to normal, the environment of my brain and peripheral tissues has not returned to normal.
However, my ability to resist attacks is improving little by little. The frequency of attacks is gradually decreasing. Two years ago, I would have attacks every 3-4 days, but this time, I haven't had an attack for nearly two weeks. And I'm grateful for the attacks. Because it makes me realize deep down that feeling healthy and energetic is a very precious thing, and that the things I worry about every day are very small.
I hope everyone stays healthy and lives a more fulfilling life.
The first draft of part of the detailed explanation to be published in the Q&A article "Is full lock necessary?" has been completed, so we would like to introduce it here.
It is important to be careful when understanding caster angle. As you may have experienced, the maneuverability and characteristics when turning are completely different between motorcycles and cars. This is because the principles of turning and the vehicle structures are fundamentally different. Unfortunately, however, there are many cases where the caster angle of motorcycles, just like that of cars, is described as "improving straight-line stability." However, this is by no means an accurate understanding. For motorcycles, caster angle does ultimately create trail and provide straight-line stability, but in essence it is an element that "creates an opportunity to turn" and disrupts straight-line stability.
自動車とオートバイとで、キャスター角の目的が異なっている事は、それぞれの角度にも表れています。自動車は直進安定性を高める必要があるのですが、キャスター角は 3度から 5度程度で、オートバイの 25度から 30度程度の角度と較べると大幅に小さく、一見、直進安定性が少なく思えます。しかし、直進安定性の為に必要なキャスター角はその程度で充分なのです。一方、オートバイのキャスター角が大きいのは、直進走行から車体を傾けて旋回を始める際、前輪が旋回方向へと向きを変える「キャスターアクション」を獲得する為に必要だったと考えられます。「キャスターアクション」は、下の図で解説している通り、操舵軸（操舵回転軸）よりも 車輪やサスペンション、ハンドル周りのステアリング系の重心点が上にある事に始まります。そして、操舵角が大きくなるにつれて、路面から受けている反力によって、更にその操舵角が大きくなるという少しやっかいな特性も持っています。 The different purposes of caster angle between automobiles and motorcycles are also reflected in their respective angles. Cars need to improve straight-line stability, but the caster angle is about 3 to 5 degrees, which is significantly smaller than the 25 to 30 degrees of motorcycles, but that is enough for straight-line stability. On the other hand, the large caster angle of motorcycles is thought to be necessary to obtain the "caster action" that causes the front wheel to change direction in the direction of the turn when the vehicle starts to lean from a straight line and turn. "Caster action" occurs when the center of gravity of the steering system, such as the wheels and suspension, is higher than the steering axis. Also, as the steering angle increases, the reaction force from the road surface makes the steering angle even larger, which is a bit of a nuisance.
以上の通り、オートバイでは、「キャスターアクション」で旋回を助けると同時に、その弊害と危険性を避ける為に、キャスター角は 30度以内の設定で落ち着いていると考えられます。そして、同時に、一般的なフロントサスペンションであるテレスコピック形式では、路面追従性を高めて、路面の凸凹によるフロントタイヤのグリップ喪失を防ぐ為にも、フロントフォークを後傾する必要があり、現在の様な角度設定になっていると言えます。つまり、オートバイ特有の特性の為に、キャスター角が設定されており、決して直進安定性の為とは言えない事が分かります。そして、仮に、テレスコピック形式以外のサスペンションが普及した際は、当然ですが、現在とは異なるキャスター角設定になる事は充分に考えられます。 As mentioned above, in motorcycles, the caster angle is set to within 30 degrees to help turning with "caster action" while avoiding its disadvantages and dangers. At the same time, in the telescopic type, which is a common front suspension, the front fork needs to be tilted backward to improve road following and prevent the front tire from losing grip due to unevenness in the road surface, so it can be said that the current angle is set. In other words, the caster angle is set due to the characteristics unique to motorcycles, and it can never be said to be for straight-line stability.
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なお、自動車が基本の学問・自動車工学では、「キャスターアクション」の定義はオートバイの場合とは異なっているので注意が必要です。自動車の場合のキャスターアクションとは、「走行時、ハンドルを切った際、自動的に直進状態へと戻ろうとする作用であり力の事」を指しています。つまり、自動車の「直進安定性」とは、旋回中にハンドルから手を離すと、操舵輪（主に前輪）が直進状態へと戻る作用であり、それを生み出している要素の一つがキャスター角です。しかし、オートバイでの旋回時には同様の作用は無く、キャスター角の目的が全く異なっている事が理解できるでしょう。 Please note that in automotive engineering, a field based on automobiles, the definition of "caster action" is different from that of motorcycles. In the case of automobiles, caster action refers to the force that automatically returns the car to a straight-line state when the steering wheel is turned while driving. In other words, the "straight-line stability" of an automobile is the action of the steering wheel returning to a straight-line state when the hands are taken off the steering wheel while turning, and one of the factors that creates this is the caster angle. However, there is no similar action when turning on a motorcycle, so you can see that the purpose of the caster angle is completely different.
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余談ですが、キャスター角が異常に大きく設定されている例を紹介します。それは、トラックレーサーと呼ばれている、トラック競技やマラソンなどで使用される車椅子です。 As an aside, I will introduce an example where the caster angle is set abnormally large. It is a wheelchair called a track racer, which is used in track events and marathons.
As an aside, I will introduce an example where the caster angle is set abnormally large. It is a wheelchair called a track racer, which is used in track events and marathons. As you know, the direction of the wheelchair is adjusted by adjusting the input to the left and right rear wheels, which are driven by hand. However, in the case of relatively simple course layouts such as competition tracks and marathon courses, the front wheels are placed far away from the rear wheels, and the length of the wheelbase increases the straight-line stability of the body, so that the athlete can drive the rear wheels with all their might. And as you can see in the image, it generally has a very large caster angle. At first glance, this may seem to be to make it easier for the athlete to operate the steering wheel, but it turns out that there is a different purpose. It is thought to be to make turns more efficient. In other words, the larger the caster angle, the greater the force exerted on the turn, even with the same steering angle. As a result, even with a small steering angle, the turn can be made effectively. However, a large caster angle also has a disadvantage. That is, even when going straight, the wheel will always start turning to the left or right due to the influence of the road surface or uneven driving force. Therefore, to counter this problem, the front wheel steering of track racers is equipped with powerful dampers and springs, which are designed to keep the car moving in a straight line at all times. When turning, the steering wheel is used to steer, and the steering angle is automatically fixed at that position. When the car returns to a straight line, the steering wheel is released, and the dampers and springs return the car to a straight line. Another reason why this mechanism is effective on track racers is the small front wheel load. In the case of a vehicle with a large caster angle, when the front wheel (steering wheel) is steered, the weight of the vehicle lowers the body on the steering wheel side. Then, when steering to return the car to a straight line, a force is required to lift the lowered body, and a vehicle with a large front wheel load has the disadvantage of requiring a large force. However, in the case of track racers, the front wheel load is basically small, and the driver's operation should be able to handle it sufficiently, so it is not considered to be a big problem.
The cooler arrived without any prior notice, the day before the cleaning day. It was a gift from Y, a long-time friend who always supports us in one way or another. It was a thoughtful gesture that was typical of him, who acts immediately when he thinks of something, without prior consultation. The motorcycle has limited loading capacity, and we also have other large equipment, but we couldn't help but respond to the thoughtfulness at least once. We made a little effort to bring it to the site, and the drinks were colder than usual. Thank you, Y.
The cleaning of Ako City Traffic Park, which was carried out on July 10, was also a road surface cleaning of the outer road, following on from the previous cleaning. However, there was less dirt and sand accumulated in the area than in the previous cleaning, and as a result, the cleaning area increased from about 18 m2 to about 23 ㎡.
Even so, the thick sediment on the road surface is a big problem, but the grass spreading on the road surface is also a big problem. In fact, the spread of grass is destroying the asphalt of the road surface. In severe cases, the asphalt that should have been paved has completely disappeared and has been replaced with soil in many places. Therefore, in such places, the grass is uprooted to prevent further destruction.
The seasons change quickly, and the park is now bathed in the summer sunshine. Dragonflies have already begun to flutter about, and a chorus of katydids has begun to echo from the grass in the park.
In places that have not yet been cleaned, there are many places where grass and grass have invaded the road surface, as shown in the image below. Every time I see it, I think, "I want to clean it up quickly," but there are too many to deal with. First, I will properly clean the roads that people who come to the park always use, and then I will gradually move on to the places that have not been touched. The opponent is more difficult than I initially expected.
GRA has held events in many places. We have held events at over 50 venues throughout Japan, many of which were made available through the "support" of individuals, which has made it possible for us to hold over 40 events a year.
The person who provided the greatest support was Mr. O. Not only did he arrange for the venue that gave us the impetus to continue our activities in 1991 when GRA was founded, but he also continued to support many of the events we held in the 1990s, arranging important venues that served as the base of our activities, making him one of the important people who supported GRA's activities.
Another big supporter was Mr. S from Honda. He works at Honda Motorcycle Japan, a subsidiary of Honda Motor Co., Ltd. He contacted us in 1994 and agreed to lend us the practice venue for Honda motorcycles in Osaka on exceptional terms. After that, he entrusted us with hosting events at the gymkhana course at Suzuka Circuit and managing events in Nara Prefecture, providing great support to GRA in expanding the scope of its activities.
Mr. I was also a very important supporter. In the early 2000s, he said to us, "I know this venue. Would you like me to negotiate for you?" and we actually made the event a reality. In the same way, he found and arranged many other venues and parking lots, mainly in Osaka Prefecture, which allowed us to continue holding events. He is a very reliable person.
And the Gymkhana Grand Prix, which we started in 1995, was also a success thanks to supporters from all over the country. This is a series of races held all around the country, competing for points earned throughout the year, and in addition to the cooperation of local clubs with experience in hosting events, there was also a lot of valuable support from inexperienced individuals who secured venues and planned the event. The first person I would like to introduce is Mr. U. He applied to manage the Kagawa GP in 1995, and not only did he negotiate and secure the venue for the first time, but he also singlehandedly handled everything from planning to running the event, and has continued to accomplish this admirably. Thank you very much. I am always impressed by your vitality.
For the Nagano GP, just like Mr. U from Kagawa, Mr. T from Nagano has been in charge of planning and running the event by himself since 1995, negotiating and securing the venue, arranging the equipment, and designing the course. He has a strong passion and determination that you would never imagine from his quiet and reserved demeanor. Thank you very much. Thanks to him, this event has become the one that attracts people from the most regions of the series.
Another person I will never forget is Mr. A from Okinawa. He personally negotiated and arranged for the venue for the Okinawa GP, and it has been held every year since. When the previous venue became unavailable, he searched for a new venue and negotiated for it by himself. There is no doubt that gymkhana has taken root in Okinawa thanks to Mr. A's efforts.
The Hokkaido GP was also a success thanks to the strong support of Mr. N. He used to work in the motorcycle industry, but this was his first time hosting a gymkhana event, and he provided detailed support from arranging the venue to announcing the event, writing releases, and planning the events on the day of the event.
The most unforgettable supporter was Mr. K, who planned and organized the Kanto GP in 1999. Despite having absolutely no experience in planning and management, he planned and managed the event with all his heart, from arranging the venue in Ibaraki Prefecture, to planning the event and writing the release text. Thank you very much. Having met someone with such strong passion as Mr. K is a great asset for us.
And Mr. Q also strongly supported GRA. Mr. Q had more passion and talent than most people, and not only did he work hard alone to hold the Kyushu GP in 2001, he also arranged the venue for the meeting in Tokyo and offered to hold the first GRA event with "trial cars", which enabled us to gather enthusiastic participants and hold the event since 2009. Thank you very much. He is a person that GRA should never forget.
I will never forget how, at the Kanto GP held in 2000, Mr. N was in charge of everything from arranging the venue in Saitama Prefecture to planning and writing the release text. Thanks to him, we have been able to continue holding the Kanto GP every year. Thank you very much. He used to live in the Kansai region and participated in many GRA events, but we are grateful for his support since he moved far away.
Mr. T has been a great supporter of the Gifu GP. Thanks to Mr. T, who confirmed the local venue and negotiated with us, we were able to hold the Gifu GP for the first time in 2001. Since then, he has confirmed and arranged new venues, so not only have we been able to hold the Gifu GP every year, but we have also been able to hold various events in Gifu.
Ise GP would never have been held in Mie Prefecture without the support of Mr. A and Mr. I. Although the two had participated in several events held by GRA before, arranging the venue and planning the event requires a completely different level of passion and determination. Thanks to their support, we were able to hold not only Ise GP, but various other events in Ise.
I will never forget Mr. U, who arranged for us to use a very special venue, a vehicle manufacturer's test course. Although this course is supposed to be off-limits to outsiders, thanks to Mr. U's efforts we were able to hold the Shizuoka GP in 2002. From then on, we were able to borrow this valuable venue every year until the Gymkhana Grand Prix ended in 2004. Thanks to him, we were able to establish a similar series, the GRA Tour, which began in 2006, as a venue to be held in Shizuoka.
In 2004, the last year of the Gymkhana Grand Prix, we were blessed with a new person who arranged the venue. Mr. H arranged the venue for the Biwako GP in Shiga Prefecture. Thanks to him, the last year of the series was a fulfilling one.
In 2006, we started a new series, the GRA Tour, in place of the Gymkhana Grand Prix, and we received valuable support from new people. They were Mr. M, who arranged the venue for Shizuoka Rd in 2007, and Mr. O, who arranged the venue for Hyotanjima Rd, held on Awaji Island in 2009. Thanks to them, the GRA Tour was able to fully achieve its original purpose.
Although it was not a series race, Mr. K from Tottori Prefecture was responsible for the planning and making arrangements for the venue and other planning work required to hold the event in a completely new area. Mr. K negotiated with various parties, including the local government, to secure the venue and ensure the success of the event. As a result, not only were many local riders able to participate and their families also attend, but the event also featured an exemplary run by police motorcycle officers, and he cooperated in planning and running the event in a way that was hard to believe was the first time. Thanks to his help, we have been able to hold several more events since then.
I have mainly introduced the people who led the event to success, even though they were trying to arrange the venue and plan the event almost by themselves for the first time. However, I must not forget the cooperation of clubs all over Japan who have experience and a track record of hosting events. These are TSRA at the Aichi GP, Hiroshima Gymkhana Club at the Hiroshima GP, and Team Cosmos at the Kyushu GP. Thank you very much. Thanks to them, we were able to hold a stable Gymkhana Grand Prix.
While I was working, I heard a voice calling out "Hey!" from the top of the bank next to the park. I looked up and saw a familiar small elderly person saying "Hey, come over here." He had found me by chance while I was cleaning up before and gave me a candy. This time, he didn't even enter the park, but called out to me and gave me ice cream and a coffee drink. I'm sure he found me this time too and went out of his way to buy them for me. Thank you. In order to fully receive his feelings, I decided to take a break so that the ice cream wouldn't melt. Thanks to him, I was able to continue cleaning up longer this time than last time. I'm grateful for that.
Since I started cleaning up Traffic Park in Ako City, I've met many different people there. People who walk early in the morning, people who walk their dogs, people who jog, people who read on the benches, etc. Many of them casually call out to me and exchange greetings with a smile. I think that's the joy of being alive. That's why I continue cleaning up Traffic Park.
In the area that was cleaned up on July 3rd, there were places where nearly 20cm of soil had accumulated and places where grass had grown widely, destroying the asphalt pavement, making the work quite hard.
The area that has been cleaned is about 18㎡, and the cleaning of the park's outer path is still ongoing. However, the number of people visiting the park is gradually increasing. We will continue to do so in order to make it a safer practice environment.
As I was working on the article "Self-steering Riding," I felt the need to touch on the "gyro effect," so I'll introduce it here. 「ジャイロ効果」とは、回転する物体が持つ様々な物理的な特性で、ジャイロスコープとは地球ゴマなどに応用されている特性です。そして、私達が乗っているオートバイでも、特に 前後の車輪（タイヤ＆ホイール）でも「ジャイロ効果」の影響を受けていて、特に、バンク時に “旋回モーメント” が発生しています。
The "gyro effect" is a physical characteristic of rotating objects, and a gyroscope is a characteristic that is applied to things like spinning tops. The motorcycles we ride, especially the front and rear wheels (tires and wheels), are also affected by the "gyro effect," and a "turning moment" occurs especially when banking.
その “旋回モーメント” が発生している様子は、下記に掲載の、高知みらい科学館 が制作した動画で確認できます。ただ、車輪の回転方向が オートバイのイメージとは逆なので、旋回モーメントも逆の方向に発生している事を理解の上でご覧ください。きっと、 “旋回モーメント” の発生が理解できると思います。 You can see how that "turning moment" is generated in the video below. However, since the direction of rotation of the wheels is opposite to that of a motorcycle, if you watch it with the understanding that the turning moment is also generated in the opposite direction, I'm sure you will understand the generation of the "turning moment."
Naturally, the gyro effect also affects "self-steering." Also, the larger and heavier the wheels are, the greater the gyro effect becomes, so in the case of motorcycles, the effect is much greater than in the example in the video. However, unlike the example in the video, in the case of motorcycles, the tires are in contact with the road surface, so I think that further consideration is needed as to how this influence manifests. For that reason, the article I am currently working on will focus on the "turning moment" that is generated when the tires come into contact with the road surface.
However, my belief remains that the function of these "turning moments" is the biggest factor in creating the unique dynamic characteristics of motorcycles. I believe that understanding and applying "turning moments" will take riding to a new dimension and bring a safer and more enjoyable motorcycle life to many riders.
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