The History Of The Gentlemen's Agreement That Capped Motorcycle Speed

Have you ever wondered why a bunch of high-performance superbikes from different brands all mysteriously topped out at 186 mph? No, it's not some physical limitation that even Emmett Brown couldn't overcome. It's because motorcycle makers did what humans do when the adults start looking at them funny — they calmed down.

What became known as the "gentlemen's agreement" was a fully voluntary accord to cap motorcycle top speeds at 300 km/h (or about 186 mph). This was a direct reaction to the top-speed arms race that was motorcycle manufacturing in the late '90s, punctuated by the Suzuki Hayabusa's ability to hit 194 mph in testing by CycleWorld. To take a step back, those speeds on four wheels can feel sketchy. The industry saw the writing on the wall and decided it would rather self-police than get policed.

It wasn't a paranoid imagination, either. A movement bubbled up in Europe with sights set on high-speed bikes, specifically looking to limit motorcycles to 300 km/h. Kawasaki USA even admitted to CycleWorld that its 2000 ZX-12R could go faster, but had to be limited to stay within these proposed limits.

Before the agreement, the sportbike world was doing that classic thing where nobody says they're competing, but everyone is definitely competing. Kawasaki's ZX-11 hit 176 mph and held the "fastest" crown for years. Honda then answered with the CBR1100XX, clocking in at 177 mph. Then that Suzuki entered the room at 194 mph — the Hayabusa was fast, fast. And before you start to check out Craigslist to see how cheap a used 'Busa is, this is only the start of the story.

The next volley came in 2000 — Kawasaki's ZX-12R, which oddly came in lower at 187 mph. And here's the part that matters for our history lesson: Kawasaki USA admitting that the bike was neutered. However, that didn't seem to stop Suzuki's 2000 iteration of the Hayabusa, with CycleWorld's testing topping out at 191 mph. Clearly testing conditions could be part of the story here, but it was clear the proposed limits were not immediate and sweeping — it was informal, after all.

If the Hayabusa was the catalyst for the change, the Kawasaki Ninja ZX-12R was the martyr. Kawasaki had a bike rumored to hit 197 mph. However, it launched in 2000, just as the agreement was being finalized. Kawasaki was stuck. They had put all their chips on black and it came up red. They had built a 200-mph bike but could only sell a 186-mph one.

Cycle World reported Kawasaki scrubbed a planned world press introduction while new electronic control units were made up to keep the ZX-12R within the proposed speed cap. To spare the brand embarrassment, rumors were spread that it was aerodynamically unstable at high speeds, but most insiders knew it was just politics. Even though it had more horsepower than the Hayabusa, the restricted ZX-12R could not beat it in top-speed tests. By 2001, the cap was unofficially official, and the Hayabusa's 220-mph speedometer was later replaced with one topping out at "just" 185 mph.

For years, the manufacturers played by the rules, but as the threat of regulation faded, so did the agreement. In 2007, MV Agusta released the F4 1000 R 312, specifically named for a claimed 312 km/h (194-mph) top-speed figure. This number that sounded better on paper than it did in Cycle World's top-speed testing, however. For what it's worth, MV Agusta was not apart of the initial group to form the agreement, but it was unofficial, after all.

Today, some manufacturers use a digital speedometer that simply stops at 299 km/h and shows dashes, even as the bike keeps accelerating. Kawasaki eventually won the whole thing anyway in 2014 by making the super-quick Ninja H2R, a 249-mph track-only monster. And if you want to see what a purpose-built land-speed car can do with a motorcycle power train, check out SuperfastMatt's build — because, apparently, a mere 270 mph wasn't enough, and now he's talking 300-plus and chasing 325.

The gentlemen's agreement saved the superbike, but in the end it just proved you can't really stop people from wanting to go fast.