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Setting the wheel size on a KT LCD3 / LCD5 / LCD8 so speed reads right

KT LCD3 / LCD5 / LCD8 (Kunteng controllers)

Wheel diameter is the second General Settings screen, in inches (16–28 plus 700C). Combine it with P2 (speed pulses per revolution) or the speed will be a multiple out.

Step by step

  1. Switch the display on. Within a few seconds, press and hold ▲ and ▼ together for about 2 seconds: the General Settings screen appears with the maximum speed flashing.
  2. Press power briefly once: the wheel diameter flashes (e.g. 26).
  3. Press ▲ / ▼ to select 16, 18, 20, 22, 24, 26, 700C (28) or 29 depending on firmware.
  4. Hold ▲ and ▼ for 2 seconds to save.
  5. If the speed is now roughly 2×, 3× or 23× wrong, go to P2 (see the assist-levels guide for how to reach P settings) and set the number of speed pulses per wheel turn: 1 for an external spoke magnet, motor pole pairs (often 23 for a direct-drive hub without a separate sensor, or 6 for a geared hub) when the controller uses the motor Hall signal.
  6. Ride next to GPS; within 3 % is good.
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. The KT list is coarse; if you are between two, choose the smaller one so the legal limit is not exceeded.

Can't find it?

Speed reads exactly half or double: P2 is wrong, not the wheel size. Speed reads about 5 % off: wheel size. Speed reads zero: the speed sensor cable or magnet, look at error 21 and 23 here on ebikecodes.

Frequently asked

What is P1 for?

Motor gear ratio × magnet count (e.g. 87 for a 5:1 geared hub with 20 poles… it depends on the motor). It sets the speed calculation when no external sensor is used; do not guess, read the motor spec.

Is there a 27.5 option?

Older LCD3 firmware: no, use 26 or 700C and accept 2–3 % error. LCD8H: yes.

Why does the LCD3 show 700C instead of 28?

Same thing.

Manuals and video

These displays are sold unbranded by many factories, so there is no single official manual. Check the manual that came with your bike, or your bike brand's support page.

Videos found on YouTube and checked automatically; they are other people's work, not ours.

Other KT LCD3 / LCD5 / LCD8 (Kunteng controllers) guides

KT LCD3 / LCD8: switch km/h to mphKT LCD3 / LCD8: assist levels and the P/C parametersKT LCD3 / LCD8: speed limitKT LCD3 / LCD8: password (C9)KT LCD3 / LCD8: backlight (C6)KT LCD3 / LCD8: walk assist and cruise (C7)KT LCD3 / LCD8: battery voltage and the battery barKT LCD3 / LCD8: throttle settings (P4, C4)KT LCD3 / LCD8: trip reset
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.