Resolving Error 21 on Biktrix eBike
If your eBike display is not showing any speed while riding or is showing "Error 21" you are likely experiencing an error with the bike's Speed Sensor. The fix may be as simple as properly aligning it!
The speed sensor consists of a sensor attached to the non-drive side chainstay on the bike along with a magnet positioned on one spoke of the wheel. The rotation of the magnet and wheel is how the bike speed is determined by the controller.
If you have a rear hub motor bike you will not have an external speed sensor like in these images. In that case please contact support for assistance in resolving the error!