I have been using a garmin edge 520 for almost 2 years now. The gps has always been reliable. But recently in the last month or so it has begun to drop out. The GPS ride data later on in strava just ends up with straight lines all over the map. However, the worst part is that i end taking KOMs in segments where i'm not even trying to take a kom.
I've read somewhere that it might be a result of having other electronic devices to close to the garmin?

That sounds really far fetched to me. Currently my garmin sits on top of my headlight (700 lumens). Has anyone else experienced this issue before?

The headlight uses an HID , right? And the cutting out happens when the light is on, particularly at less than full intensity? Lower intensities are achieved via rapid cycling of the power to the HID. This can cause RF interference. The GPS satellites are 500 miles in the sky emitting a signal that has very low power by the time it reaches you. HID lights interfere with wireless bike computers too. The proximity may need to be adjusted.

Forgetting to start and stop the timer will cause you to to not have data either and will result in straight lines between the times the timer was stopped/started. Of course you wouldn't have data for anything during that period if that was the case.

Also, has where you ride changed? It doesn't take much to block a gps signal. Terrain, dense wet foliage, your body if the signal is already weak and as noted RF interferance from other sources.

Move the GPS elsewhere on your bike or turn off other things and see if you note differences.

I'm not sure if it's a HID light (forgive my ignorance first time i have heard of HID. Learn something everyday! ). I have the "light and motion 700" , but you may be right with the lower intensities. I will take more notice of it next time. The light has 4 modes:Lumens700 (high), 350 (medium), 175 (low), 175 (pulse).
I generally run it at 350 or pulse setting as i do my training rides with the group early in the morning when it's dark and then commute to work afterward so i need the battery to last for a few hours. I like to have day time running lights as drivers really hate cyclists here in Sydney

I thought the garmin auto start/stops the timer? i'll double check that later today. But you could be onto something here:


the blue circles is where i stopped. Once at the meeting point with the group and another for coffe before heading home.

Thanks for the insights this has all been very helpful.

High Intensity Diode (really bright Led) That's what you've got. Either move the computer further from the light (I had to put mine on the top tube) or switch to wired instead of wireless. I had the same problem. But it didn't matter whether I was using my L&M light or my Cygolite. Both interfered similarly with my wireless computer when on lower intensities. I switched over to wired on one bike and GPS on the other eventually, so it's no longer a problem for me.

Well you know you have to start the timer initially for the auto-stop/start to function. However it might be wise to check the auto stop/start settings. Most probably leave theirs set to 0, however on my edge 500 I have it set to less than 3 mph (not quite 5 kph). This solved some issues for me that have been so long ago, I'm going to have to think about it some to remember the exact issue that solved.

I'd also recommend that you don't rely on the auto stop/start for anything but short stops while you remain on the bike. If you are getting off the bike for a period, then use the stop. You'll get a message asking to save/discard, but just ignore that and swipe it away if you can or change pages. You do have to remember to push the timer again when you start back and till you get that routine down, you'll mess up some rides. The main reason I do this is because I put my gps in my pocket when I leave the bike and I don't want it stopping and starting while I'm not riding.

Many don't like the auto-shutoff feature as it will turn their device off after so many minutes when the timer is not started. I use it though. If you don't find that the light is the cause of the interference, then enable your auto-shutdown and if the 520 lets you, then set it to a low value. Then if your device shuts down on a ride, you'll have to suspect it has something to do with the timer.

A year or so after I got my edge 500, it started shutting down on several of my long rides. Took several to find the cause, but surprisingly it was me. While juggling my water bottles to swap the empty down tube bottle with the seat tube bottle I learned that the timer button was getting tripped in the dance taking place on the top of the handle bars. The 520 is a different button though, so maybe less likely.

An update.
For the benefit of anyone who may also have this problem of gps dropping out during a ride.

STRAIGHT LINES IN GPS
My auto stop/start was "off" deeerr! but i like the idea of the stop button and scrolling away to a different page (thanks Iride01) i'll do that from now on.


GARMIN GPS DROPOUTS
It is due to the position of the light. I previously mounted the light on my handle bar, but when i got a new bike with the flat bars i purchased a new mount that lets you mount the garmin and the light beneath it (via a gopro attachment).
That's when the problems started. So after moving the light away and checking my ride data here is the proof.




The course (10 laps)




GPS Light mounted on handle bars. GPS tracking not perfect but the course has many tall trees towering over the track. It also DID NOT drop out.


Light connected underneath the garmin via gopro mount. The garmin actually "lost satellite connection" all together during the ride and didnt connect again until the ride was over.

Did any of you have problem with the GPS 'clock' reset recently, was that what I was reading about?

I was riding by a Marine base recently and my garmin must have gotten lost 20 times. I really got tired of the constant beeping. The map was tracking okay, must have just been outside the radius that garmin allows before declaring itself off-route.