Over the years this word has been a catch all for anything “odd” styling in Japanese car culture as viewed by a foreigners perspective. Car has takeyari muffler? Bosozoku. Motorcycle with sandan seat? Bosozoku. While this thought process isn’t fully wrong, there are other words that could be used to better describe it.
To preface this, there are a few words you will keep seeing pop up. Bō-Sō-Zoku is written with 3 kanji charaters, 暴走族. Bō (暴) means violence. Sō (走) means to run/drive. Zoku (族) means a group/tribe of people. Violent Running Tribe is how you will see a lot of people define it, but there is more to it than those 3 words.
History
In the 1970, with the rise of affordable motorcycles, “bad boys” flocked towards them. At the time they were called Kyōsō-zoku or crazy running tribe. These types of people where known for assaults and blackmail. It wasn’t until they started turning on regular citizens and other groups that the name changed to “violent.”
By 1972, the name was wide spread to where news organizations and police departments started using “bosozoku” to classify these types of people. Similar how in America the police started classifying outlaw motorcycle gangs.
These groups of motorcycle riders started to increase in 1972-1974 as incidents started to climb. By 1975, there were 571 of these groups and over 23,000 members nationwide. Members would arm themselves with knives, molotovs, and nunchucks. Around 1977, large gatherings would happen around holidays with thousands of motorcycles and cars. Police tried to fight back with traffic blocking and limiting. To fight back, the Road Traffic Act of 1978 added a prohibition against riding two or more vehicles/motorcycles side by side in one lane.
The peak of bosozoku happened around 1982, with over 42,000 members and over 830 groups. It is estimated as of 2020 that there is under 5,714 that are still classified as “bosozoku.”
So what does this all mean?
Bosozoku was used to describe the violent groups at the time and was considered a negative term for this subculture. As time went on, this subculture wasn’t only about the crime and violence. The car and motorcycle stylings stand alone without the need for gangs.
Now that it has been decades since the 80s, the stigma against the word bosozoku still remains in Japan. Which is why many of the car and motorcycle enthusiast use different terms to describe their machines. Kaido racer (街道レーサー) was coined by Holiday Auto magazine in their reader submitted car photo section titled “Oh! My Kaido Racer.” Old motorcycle owners now refer to themselves as Kyusha-Kai (旧車会), or classic motorcycle/vehicle group. These tend to be riders not associated with a group or commit violent acts, but still style their motorcycles like they did back then. Another term that is popular to describe the motorcycles is Zokusha (族車) or tribe vehicle.
In summary
This style and subculture have been around for five decades now, and the people have evolved too. Many of the old car and motorcycle enjoyers aren’t the violent teens they were in the 80s. With that, the vocabulary changes.
I know for many foreigners learning about this style, bosozoku is usually the entry level word used to describe it. Hopefully this website will help guide you into using this word less to describe the world around these old cars/motorcycles.
Sources: Wikipedia JP, Kuruma-news, Yahoo Questions