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Setting the wheel diameter on a King-Meter J-LCD, SW-LCD, K5345 or SW102

King-Meter J-LCD / SW-LCD / K5345 / SW102

Wheel size is the first basic setting on most King-Meter displays, in inches. On some firmware it needs the P/C menu (P1 = wheel).

Step by step

  1. Switch on, then press and hold ▲ and ▼ together for about 2 seconds. J-LCD and K5345: the first setting flashes (wheel size or backlight). SW-LCD (small 2-line): hold ▲ and ▼ for 3 seconds. SW102 (tiny 3-button): hold + and − together. Menu order differs by firmware; use the item names.
  2. The wheel size flashes (or step to 'Wheel' / P1 with power). Set 16–29 or 700C with ▲ / ▼.
  3. Power (short press) moves to the next item; ▲ / ▼ change the value; hold ▲ and ▼ (or wait 10 seconds) to save and exit.
  4. If speed is a clean multiple wrong, look for the speed-pulse parameter (P2 on J-LCD firmware with a P menu: 1 for a spoke magnet, pole pairs for a Hall-based readout).
  5. Verify against GPS.
Tip: Circumference reference (ETRTO tyre on a normal rim): 20" ≈ 1590 mm, 24" ≈ 1910 mm, 26" ≈ 2075 mm, 27.5" (650B) ≈ 2150 mm, 28" (700C) ≈ 2200 mm, 29" ≈ 2300 mm. Fat or plus tyres add 60–120 mm; a roll-out measurement (mark the tyre, roll one full turn, measure) beats any table.

Can't find it?

Wheel size shows dashes: OEM-locked to protect the speed limit; the published 1919 or 0512 code in the Advanced menu (hold ▲ and ▼ again from the settings screen) unlocks it on some firmware, not all.

Frequently asked

27.5 available?

On newer J-LCD firmware; otherwise 26 or 700C.

Does the controller need it?

On King-Meter systems the controller reads the display's value for the cut-off, so yes.

Speed frozen at 0?

Sensor or magnet; see error 21 here.

Other King-Meter J-LCD / SW-LCD / K5345 / SW102 guides

King-Meter J-LCD / SW-LCD: switch km/h to mphKing-Meter J-LCD / SW-LCD: speed limitKing-Meter J-LCD / SW-LCD: passwordKing-Meter J-LCD / SW-LCD: battery voltageKing-Meter J-LCD / SW-LCD: walk assist
Still stuck? Take a photo of the display and show it to a local e-bike workshop. Bring the bike's system name (e.g. Bosch Performance Line CX) and the exact code; that saves diagnostic time and money.