> ## Documentation Index
> Fetch the complete documentation index at: https://docs.time2.bike/llms.txt
> Use this file to discover all available pages before exploring further.

# Transponder mapping

> Map RFID chip IDs to riders so live timing knows who crossed the line.

For RFID-timed events, each rider's plate is associated with a **transponder** (chip). Time2Bike needs to know which chip belongs to which participant so reads from the decoder resolve to names and bibs.

Manage the mapping at `/organizations/[id]/events/[eventId]/transponders`, accessible from the event nav next to **Bibs**.

## Adding a mapping

1. Enter the **Transponder ID** as it's printed on the chip or returned by your decoder.
2. Enter the **Participant ID** — the MongoDB ObjectId of the registered participant. Copy this from the **Bibs** or **Registrations** page row.
3. Click **Add mapping**.

For events with an active timing session, the table also shows the rider's **plate** and **name** alongside each mapping so you can sanity-check the assignment.

## Bulk loading from a chip vendor

If your vendor (MyLaps, ChampionChip, RaceID, etc.) provides a CSV that maps chips to riders, use the [Imports](/organizers/events/imports) flow to load it as a registrations import — the same plate column doubles as a chip assignment when the timing system is configured to look there.

## Removing a mapping

Click the trash icon on any row. The chip becomes unmapped and future reads will show as **unknown** until you reassign it.

## Sanity-check before race day

1. Hand-verify a handful of bibs against their chips.
2. Walk a known chip past the decoder and confirm it shows up under the right rider in **Live results**.
3. Make sure every starting rider has a row in this table; missing rows mean an anonymous timing read on race day.

## See also

* [Hardware → RFID](/timing/hardware/rfid) — physical setup of decoders and antennas.
* [Bibs](/organizers/events/bibs) — assigning plate numbers.