Which events are timed with RFID chips and where the chip goes

When a participant does not even stop at the finish and their time is recorded on its own, an RFID chip is usually behind it. The technology has been used in event timing for decades, and today you find it from small school runs to large racing series. Let us go through which events are timed this way, why RFID suits them, and where the chip goes in each sport.

RFID timing in short

A passive UHF chip has no battery. The reader's antenna emits a signal, the chip draws a moment of energy from it and answers with its code. That makes it cheap (it costs cents) and it survives frost and rain, which suits mass events. An active transponder has a battery and transmits by itself. It is bigger and pricier, so it is used where long range and high accuracy are needed, especially in motorsport. The band for passive UHF chips depends on the region: 865 to 868 MHz in Europe, 902 to 928 MHz in the USA and Canada, 920 to 925 MHz in China and roughly 916 to 921 MHz in Japan. The chips are often wideband, but the reader must be made for the band of the country where the event takes place.

The reader reports a chip repeatedly while it stays within reach of the antenna, so one passing produces several reports. The software turns them into one passing: it records the first read and ignores further reports of the same chip within a short window. That is why a reader can handle a dense finish, dozens of chips at once.

Running: from a 5K to an ultramarathon

Running is the most common use of RFID. Road races, trail runs, cross country and school competitions are all timed with a chip on the bib. The reason is simple: crowds form at the finish and nobody can note down by hand who just crossed.

Placement has to take the body into account. The human body is mostly water, which absorbs radio waves, so a chip pressed against the skin reads poorly. In our test we held a chip against a bare stomach and the antenna did not read it at all. That is why running tags have a foam layer underneath that separates the chip from the body by 5 to 15 mm. Wear the chip on the front and on top, never in a pocket or under a jacket.

Triathlon, duathlon and open-water swimming

In several disciplines the chip is fastened to the ankle with a strap and stays on the participant through the whole event. Readers in the transition zones record splits, so you know how long the change from water to bike or from bike to run took. Pool swimming is usually timed with touch pads, RFID comes into its own in open water and in multisport.

Cycling: road, gravel and MTB

Cycling marathons, gravel and MTB events are timed with a chip on the bike or on the helmet. A bike has metal though, and metal detunes the chip. An ordinary chip stuck straight onto metal stops working because the metal short-circuits its antenna. There are two solutions: an on-metal chip, or an ordinary chip with a gap from the metal, meaning a holder or spacer roughly 5 to 10 mm thick. On a fork the chip is usually fastened with a cable tie.

Our test was clear. An on-metal chip worked well on a bike, yet the same chip held against a small curved metal bottle was not read at all. On-metal chips use the metal as part of their antenna and need a large enough, above all flat, surface. In MTB enduro individual stages are timed, so readers stand at the start and finish of each stage.

Motocross, enduro and other motorsport

A motorbike combines all the problems: a metal frame and fork, a layer of mud and plastic covers. Thin clean plastic does not bother radio waves, while metal, carbon fibre and metallic paint damp them like metal does. Wet mud damps them too. Proven places are the front number plate (plastic, facing forward), the front fender, and the fork with a spacer or an on-metal chip. The rear tends to be the muddiest. If you can, use two chips per rider, for example one on the plate and one on the helmet. In motocross RFID is also used to count laps after a mass start, and professional series often use active transponders.

Obstacle races and rough terrain

Obstacle races bring mud, water and physical contact. Bibs get lost and dirty, so the chip often goes on the wrist or ankle and is protected by a waterproof case. What helps here is toughness: a chip with no battery in a solid case survives immersion and knocks.

Winter sports

Cross-country skiing, ski mountaineering and other winter events use a chip on the bib or on the ankle. A passive chip has an advantage here: it has no battery, so frost does not affect it, unlike active transponders whose battery life drops in the cold.

Lap events and charity runs

In 24-hour races, relays and charity runs participants cross the finish repeatedly. The reader records every passing and the software builds the laps and the running order from them. It suits children's, school and club events just as well: chips are cheap and a reader copes with a group of children finishing together.

When RFID is not ideal

The antenna records a chip when it enters its zone, not exactly when it crosses the line. That is why RFID suits results in whole seconds and a dense finish without queuing, but not hundredths of a second. For sprints, track running or official motorsport tests where hundredths are required, you need photocells or professional decoders. For very small events, a few dozen participants, manual timing is often enough.

A checklist for organisers

• A reader made for the band of your region (Europe 865 to 868 MHz, USA and Canada 902 to 928 MHz, China 920 to 925 MHz) and chips that cover that band.
• The chip always on the outside and with a gap from the body. On metal use an on-metal chip, or a 5 to 10 mm spacer.
• Run 20 test passes at different speeds and count how many were recorded. Repeat it wet and with a muddy chip.
• Set the antenna power so the read zone matches the course. Needlessly high power widens the zone and the first read comes too early.
• Prepare a backup: for a missing chip, enter the passing by hand, in TAQIO by tapping the participant's name.

Where TAQIO fits in

TAQIO takes the chip code from an RFID reader, matches it to a participant and records the passing straight away. In lap events it counts the laps and shows results live. If a chip is missing, you record the passing by hand. The app also works without internet and sends the records once the signal returns. If you would rather not source hardware yourself, TAQIO offers chips and readers tested directly with the app.