How to set the wheel size on a Bafang DP C18 / DP C07 / DP C10 so speed and distance read correctly
Wheel size sits under Information on the DP C18 and is entered as a diameter in inches. Get it wrong and speed, distance and the legal speed limit are all off by the same percentage.
Step by step
- Switch the display on, then press and hold + and − together for about 2 seconds until the Setting menu appears (Display Setting / Information / Exit).
- Press − to highlight Information and press power to open it.
- Scroll to Wheel Size (shown as e.g. 26", 27.5", 28", 29", 700C) and press power. If the value does not flash, your firmware has locked it and asks for a service code; the published Bafang code is 8018 (enter each digit with + / −, confirm with power).
- Press + or − until the correct diameter shows. Choose the ETRTO size printed on your tyre, not the rim: a 27.5 × 2.8 plus tyre rolls closer to 29".
- Confirm with power, scroll to Back / Exit and leave the menu.
- Check: ride next to a car, a GPS app or a marked kilometre. Speed should agree within 2–3 %.
Can't find it?
On BBS02/BBSHD conversions the wheel size the display shows is only used for the speed readout; the controller uses its own wheel size programmed with the USB cable. If speed is right but the limit kicks in early, the controller setting is wrong, not the display.
Frequently asked
What is 700C in inches on the Bafang menu?
700C is the 28" road/trekking size (circumference about 2200 mm with a 40 mm tyre). Pick 28" or 700C, they are the same entry on most firmware.
Speed reads 10 % too high after a tyre change, why?
A narrower tyre has a smaller circumference. Re-measure the roll-out and pick the next size down.
Why does the display ask for a password at Wheel Size?
Some OEM firmware locks wheel size and speed limit behind the service code 8018 so riders cannot defeat the speed limit by entering a tiny wheel. Enter it once; it does not persist.