Numbers are synonymous with bike racing. Not only are they a form of recognition for fans, commentators and organisers from trackside and on television graphics but are often regarded as sacrosanct and something a rider will carry throughout their racing career. A lesser known fact is that the displaying of each number is subject to a rigorous set of regulations.

Greg Haines reports from Seat 21F of a Boeing 767 flying from Vienna to Barcelona after the Czech round of the World Superbike Championship at Brno, where he was commentating for Eurosport and reporting for Motorcycle News

#7 is famously associated with Barry Sheene, 93 with Marc Marquez, 99 with Jorge Lorenzo, 65 with Jonathan Rea, 91 with Leon Haslam and most famously 46 with Valentino Rossi. Seldom will they jettison their preferred combination of digits, only when given the privilege of running a Champion’s #1 – and even then they don’t always do it. Nine times out of ten, each number has a story of its own ranging from a birthday or birth year to superstition, a lucky number or simply what the rider was given at random when they started racing.

Nowadays the use of rider numbers signify much more than a form of identification. Entire marketing campaigns are built around the numbers for social media, television, billboards in cities and banners in circuit grandstands. Indeed, Valentino Rossi’s identity has its own aura as well as a vast merchandise and clothing range. The brand VR46 is more globally recognised than the name MotoGP itself.

Before a number is used for any advertising or promotion it needs to become known on the bike itself. This can only happen in a certain way. If a number is not correctly displayed on a bike, teams can face sanctions from the organisers.

Each series has its own regulations; for the sake of this example we will use the code laid out by governing body the FIM in the World Superbike Championship, where bike numbers must be black and displayed on a white background.

The numbers on the front of the bike must have the following minimum dimensions:

Height: 140mm

Width: 80mm

Stroke: 25mm

Space between each number: 10mm

There are also minimum measurements for numbers shown on the sides of the bike:

Height: 120mm

Width: 70mm

Stroke: 20mm

Space between each number: 10mm

It gets more complicated. The number on the front must be centred or fractionally to one side, such as the #76 on Loris Baz’s BMW which is positioned just off to the side so as to not cover the headlamp stickers which mirror where the actual lights would be on the road-going bike (the light stickers are obligatory to make the bike look as much like the road bike as possible, although real headlamps are not necessary in WorldSBK and would mean the bike is carrying more weight than necessary).

In a further bid to make the number as visible as can be, no sponsor logos are allowed within 25mm of the numbers. As well as being stuck on the front, rules state each bike must also have its number displayed on the lower rear portion of the left and right side fairings. Once again, the number must be in the middle of its white background; if the team wishes to change this, it must receive official confirmation from FIM Technical Director Scott Smart at least two weeks before the first race of the season. If the rider, their team or a sponsor prefers the number to have a border, it must be a contrasting colour; the maximum width of this outline is 3mm in a bid to avoid its colour overpowering the black of the number itself. Any border must must surround the entire number. Reflective or mirrored numbers (like the writing you see on the front of an ambulance) is strictly not allowed. If a rider is running a number in double or triple figures – like Rossi’s 46 or World Supersport Champion Lucas Mahias’ 144 – each digit is not allowed to overlap, thus evading any confusion.

There is more still! It is not just the size and colours of the numbers which are sternly policed, but the fonts as well. Illustrations showing dimensions and the list of eight available fonts can be seen below, exactly as shown in the official regulations.

Detailing the permitted dimensions of each digit The eight fonts available to the riders

Simples? The rules are clear but do not always stop teams from making mistakes or not reading the regs properly. In any disagreement about how a number is displayed on a bike the final say goes to the FIM Technical Director. He is one individual compared to the many members of a team, but he is never outnumbered!