How it Works
The SL-R1+ must be parallel to the ground with the lens pointing opposite to the direction of movement (backwards) in order to detect the correct braking direction. When you slow down rapidly, the SL-R1+ changes from the current light mode to solid mode at full brightness for 2 seconds (or longer depending on how fast you are moving) then returns to the current light mode.
Limitations
If the SL-R1+ is not parallel to the ground it may not provide accurate braking detection.
Riding uphill or downhill may cause false-positive brake detection or missed brake detection.
Vibration of the light may cause false-positive brake detection or missed brake detection.