I've had great experiences with the Garmin 820 since owning it and purchasing it in August 2016. It has been solid throughout. Until recently.
The speed displayed is now becoming frequently inconsistent, jumping around between 0.5-2mph when my speed is constant.
I'm really unsure of what is causing this and have attempted a few things to rule out possible interferences.
First, I recently purchased an Akasio V50 Elite action camera. I noticed after a few rides with it being used, (mounted on the handlebar), speed readings were jumping up and down 5-10mph, which was really spastic.
Attempted solution 1: Speed Sensor battery and sensor replacement
While I was using a Gen 1 Speed Sensor, I did put in a new battery, but did not solve the issue. I had a newer Gen 2 Garmin Speed Sensor, which I used to replace the Gen 1, but again did not solve the problem.
Attempted solution 2: Action camera location change and removal
I changed the mounting location to my helmet but the speed fluctuations continued. Two days ago, I had the camera mounted on the helmet, but not turned on. Speed fluctuations were still present, but in the smaller range of 0.5-2mph.
I returned home due to a bike issue I needed to address and took the camera off. Going back out on my ride, the speed readings seemed to be much better, like it is supposed to work.
Obviously, I deduced that the camera was the culprit of the fluctuations.
However, on my ride today, at a different location than I usually do for my normal ride, the 0.5-2mph fluctuations returned about 15 miles into the ride.
A bike bell is the only thing that is mounted to the handlebars and has no magnets. I have a magnetic helmet chinstrap on one helmet (Specialized S-Works Evade) and a magnetic helmet light on the rear of the helmet.
Frankly, I've used the helmet plenty of times in the past without issue so really doubt the small chinstrap magnet is the problem.
I also have a hard time thinking that the helmet light on the back of the helmet would be an issue also. I've been using that for a couple of months.
Bike is a 2011 Specialized Roubaix Expert SL3 with Ultegra mechanical groupset. The Garmin 820 is updated with the most current software available. I ride daily so notice the slightest changes. My daily workout ride is also extremely consistent with route and mileage.
Has anyone else experienced this issue?
