Where & how to wear triathlon ID numbers (tattoos & belts)


Race identification is important in any sport on race days. In triathlon, as a competitor, you will need several identifiers for the race: on the skin, on the helmet, on the bike, during the run, and the swim… and it can be quite overwhelming to follow. As a spectator, you can easily tell apart triathletes from other sports on race day thanks to their lovely body marking, race tattoos, and race belts. So let me introduce all there is to know about race day identification in triathlon.

Why do we need race identification numbers?


Officials need to be able to identify participants during a triathlon race. The race number has to be clearly displayed at all times during the race to allow quick identification. It can be tattoos, stickers, bibs. Race identification is also useful for the athletes to find their equipment.

Body marking is not very common in sports events. It is really important in triathlon due to the swim portion. It is essential for your safety that lifeguards and medical support can identify you at all times during the event and quickly obtain information about you if something was to happen to you.

What’s an official race number or race bib?

The official race number – race bib – is a piece of paper/plastic with an identifying number that must be pinned to the competitor outfit or to its race belt. The number is printed to be easily readable from a distance. Not wearing a bib during a race can incur a time penalty.

Where do you place triathlon numbers?

At least 5 identifications are required: on your body, on your bike, on your helmet, on your racing bib, and on a provided swim cap. This ensures you and your equipment can be identified at all times during the event.

According to World Triathlon (ex ITU) – the international governing body for triathlon and related sports – there are many race numbers to be displayed during the race:

The race packets will contain a minimum of: five (5) official race numbers (one (1) for body, one (1) for bicycle and three (3) for helmet) and four (4) safety pins, numbered swim cap, timing chip, accreditation pass, athletes’ guide, tickets for all of the social functions.

World Triathlon, age-group rules
Example of triathlon race packs

United States specific rules

If you are racing in the United States, it is most likely that your event will be under USAT regulation. USAT adheres to World Triathlon rules but has its own set of rules to clarify some of the points. In the case of race identification USAT really emphasize the fact that your race ID must be visible and readable at all time during the race and that you must wear the provided identification swim cap. See the rules detailed below:

“Race Numbers. Participants shall plainly display their race numbers at all times, and shall maintain the race number in an unaltered, unobstructed and readable state at the start and finish gates, in the transition areas, and on the course. Any violation of this Section shall result in a variable time penalty.”

“If provided by race management, a swimmer must wear the proper official swim cap corresponding to his/her wave. If a participant chooses to wear two caps, the official swim cap must be worn on the outside.  Failure to wear the official swim cap, may result in a variable time penalty. For safety reasons if no official cap is provided, all swimmers should wear their own brightly colored swim cap.”

How do you wear triathlon numbers?

Race bib and race belt

An important rule about the bib number – that you have to wear pinned on your t-shirt or race belt – is that you must have it worn at all times during the run leg on the front.

“Mandatory for the run segment”

“Must be visible on the front during the run segment”

Body marking / tattoos

About body marking, there are a few rules also which specify a bit more in detail what you have to do:

“The Local Organising Committee will provide body marking or body marking decals, who will apply them prior to the event”

“Body markings are to be applied to each arm, unless instructed otherwise by the World Triathlon Technical Delegate at the briefing”

“Body markings and/or decals using multiple digits will have numbers appearing one above the other, not side by side”

“One calf of each athlete – if not covered – will be marked with the category and gender of the athletes”

The important point to remember here is that your race ID has to be written digit per digit from top to bottom on your arms.

Body marking (vertical digits)

Bike and helmet IDs

In your race pack, you will be provided with race numbers to put on your bike and on your helmet. Instructions on where exactly to put them can vary between triathlon events and will be provided with your race pack.

Generally, the sticker of the bike is to be attached to the seat post with the number heading towards your rear wheel. For the helmet sticker, generally, it is to be put on the front of the helmet in the center.

Do I need a triathlon race belt?

A triathlon race belt is not mandatory but highly recommended. Indeed, in order to comply with the “unobstructed and readable” rule, many recommend having the race bib on your back during cycling and on the front during running. A race belt allows doing that easily by sliding it around your waist.

Race belts are great to race without worrying to be asked by referees to reposition the pins. They save time and are more likely to stay in place (less chance to lose the bib). They can be found for around $10 on Amazon which is worth the investment in my opinion.

Triathlete wearing his bib on a race belt (at the back for the cycling)

What do triathletes use to write on skin?

During triathlon races, triathletes write their race number on their skin with a permanent marker. It is generally done by the organizers before the race using non-toxic marker pens such as SportSafe markers (recommended by USAT).

SportSafe markers are made for sports events and are safe for the skin. They can withstand being in the water, they can handle soap and long hours covered by sweat without the writing wiping off. Unlike industrial markers, they do not contain toxic ingredients. They are FDA-compliant cosmetic ingredients.

On a side note, it is recommended not to put sunscreen on before being marked up. You can apply it once the ink has dried on your skin.

What about decal tattoos?

In some events, decal tattoos are provided in the race pack. These are a good alternative to marker pens of body identification. They are much more readable and last longer, which can also make them harder to remove after the race.

Some people find these decal tattoos very appealing. It’s a way to brag about doing triathlons as well as a nice little souvenir.

Xterra triathlon calves tattoos (age group identification)

How to remove body marking and stickers after the race?

Temporary tattoos and body marking made with specific sports markers are made to stand up to soap and water. To remove them, the best solution is to scrub the marking with baby oil or try directly baby wipes. If that’s not enough, you can try non-alcoholic disinfectant wipes, rubbing alcohol, or even make-up remover.

For the bike and helmet, it can be quite tough to remove the adhesive residue left by the stickers. You can try GooGone or Uni-solve adhesives removers. These products won’t damage the paint of your bike.

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