Here is the procedure for stetting a Vetta C-10 Cycle computer.

 To set the wheel size - press the RIGHT button until the ODO is displayed. Then press the LEFT button for more than 2 seconds. The wheel size will show up. Use the right button to advance the flashing digit, the LEFT button to change the digit. The wheel size is the circumference of the wheel in mm.

  To toggle MPH to km/h - From the ODO display - Press BOTH buttons for more than 2 seconds. Use the RIGHT button to toggle from MPH to KMH, the LEFT button to set.

 To set the clock - From the time display, hold the LEFT button for more than 2 seconds. Use the right button to advance the flashing digit, the left button to change which digit and then to set.