randomly (?) flashing headlights in auto mode

I have the Edge 820 Varia Radar taillight and the Edge Remote, the only options I currently have for the Custom button on the Remote are:-

Start & Stop the Timer
Start Timer
Stop Timer
Turn Backlight On
Show Map
Show Compass
Show Elevation Profile
Show Lap Summary
Show Virtual Partner

You can select any two of the above, one with a Long press of the button and the other with a Short press.

I did put a suggestion in to Garmin a while back requesting the option to cancel a Segment, maybe you could put in a request for what you require.

The AUTOMATIC control of the headlight is based on a combination of ambient light conditions and the time of day.

For headlights that support flashing I think it goes like this

Daytime with high ambient light - flash mode

Daytime with medium ambient light - flash mode

Dawn/dusk (low to medium ambient light) - medium beam

Night (low ambient light) - high beam

thanks guys!

I'll contact Garmin to make some suggestions and report bugs then, because the flashing in my case is often occuring when it shouldn't: in complete darkness at night time, and constantly switching between fixed and flashing at dawn/dusk.

I'll probably try and block the light sensor of the 820 too, in order to stop the lights from flashing when I REALLY need a fixed beam. hopefully I figure out where it is placed...!

If you take the light network out of auto mode you can control what the light do manually through the Edge.

thanks for the suggestion aweatherall... still, changing the settings via the 820 requires a good dozen presses... masking the top left corner of the unit is a lot faster way to disable the auto mode and prevent intempestive flashing... now debating wether I should fabricate some sort of flip on cover for night time with some masking tape or wether using my hand when I encounter tricky conditions for the sensor will be enough :P I actually like the auto mode, because of these very long tunnels I sometimes go through during day time...!

I eventually understood that the 820/varia headlight couple only reacts to light: the brightest ambient light, the lower the power setting and when brightly lit, it flashes. BUT there are 2 BIG issues

1- inertia : in fast changing light conditions -night time with cars and lamp posts etc.- the light adjusts a dozen seconds too late, hence the flashing and light intensity changes seem pretty random
2- sensor placement: since the edge 820 is tilted towards me, the sensor is extra sensitive to light condition behind me, not in front (where it actually matters)!

all this explaining my issues with building angles lit on only one side, and similar conditions. if one side is brightly lit and I'm heading fast towards the unlit side of the building, the light will start flashing only once the light source is behind me: once i'm in complete darkness !

One thing that might help you in the future. I don't know if have a Di2 system with a D-fly, but Garmin recently added light control as one of the configurable options on the Edge 1000 for users with Di2 button integration. I suspect that this will get ported to the 820 at some point.

YES ! that will help...! in that future in which I own a di2 bike :P !

One thing that might help you in the future. I don't know if have a Di2 system with a D-fly, but Garmin recently added light control as one of the configurable options on the Edge 1000 for users with Di2 button integration. I suspect that this will get ported to the 820 at some point.

I believe it's for the Dura Ace Di2 not the Ultegra Di2

Dura Ace. It needs the shifters with the buttons that are under the hoods.

I know it’s getting a bit off-topic, but… Out of curiosity, can the extra control buttons be connected to Ultegra Di2?