Fenix 5 vs Forerunner 235 GPS Test

I finally got around to wearing both my Fenix 5 sapphire and Forerunner 235 on a run today. I tried as best as possible to have a level playing field and reduce the variables to do a fair comparison.

Fenix 5 Sapphire
Beta 4.04 (beta)
GPS: 4.3
GPS + GLONASS
1 second recording

Forerunner 235
7.30
GPS 3.0
GPS + GLONASS
1 second recording

Setup:
- I rebooted both units, then did a GPS soak for 20 minutes in clear skies with no obstructions. Oddly enough, the F5 registered 0.04 miles after the soak, where the FR235 registered 0.01 miles.
- I wore the F5 on my left wrist, and the FR235 on the right wrist. I gave both devices 5 minutes to stabilize the GPS and HRM before I started the activity.
- I ran in a suburb area with mostly wide open skies, and occasional trees. No tall buildings or other obstructions.

On the run:
- I attempted to run a mile at my base training pace, 8:10 min/mile. Followed by a run at marathon pace, 7:45 min/mile. Followed by a few recovery miles, 8:30 min/mile.
- It was challenging to lock in a pace because the devices rarely showed a simliar current pace. They were consistenty 15-30 seconds per mile different. A few times the F5 was off by more than a min/mile.
- The FR235 current pace seemed way more stable; there were definitley less fluctuations. The F5 pace was all over, unless I was running in a straight line for a good distance. I'm not sure which was more accurate/precise, but the FR235 does a better job at smoothing.

After the run:
- I used DCRainmakers anaylzer tool to do the comparison, as well as MyGPSFiles. I also uploaded them to Garmin Connect to see how Garmin viewed the files.
- The FR235 showed a more smooth pace. The F5 has more fluctuations. Again, not sure wihch is more accurate or precise.
- The FR235 did better around corners or under trees. The F5 was often taking corners wide, or short.
- The were both decent at straight lines.

Pace Graph:

DCR Analyzer GPS Maps:
(Fenix 5 is the purple line, FR235 is the blue line.)

I'll do some more runs to compare, but I'll alternate wrists, and I'll also compare the GPS vs GPS+GLONASS.

0 FeelX86 over 7 years ago

I finally got around to wearing both my Fenix 5 sapphire and Forerunner 235 on a run today. I tried as best as possible to have a level playing field and reduce the variables to do a fair comparison.

Fenix 5 Sapphire
Beta 4.04 (beta)
GPS: 4.3
GPS + GLONASS
1 second recording

Forerunner 235
7.30
GPS 3.0
GPS + GLONASS
1 second recording

Setup:
- I rebooted both units, then did a GPS soak for 20 minutes in clear skies with no obstructions. Oddly enough, the F5 registered 0.04 miles after the soak, where the FR235 registered 0.01 miles.
- I wore the F5 on my left wrist, and the FR235 on the right wrist. I gave both devices 5 minutes to stabilize the GPS and HRM before I started the activity.
- I ran in a suburb area with mostly wide open skies, and occasional trees. No tall buildings or other obstructions.

On the run:
- I attempted to run a mile at my base training pace, 8:10 min/mile. Followed by a run at marathon pace, 7:45 min/mile. Followed by a few recovery miles, 8:30 min/mile.
- It was challenging to lock in a pace because the devices rarely showed a simliar current pace. They were consistenty 15-30 seconds per mile different. A few times the F5 was off by more than a min/mile.
- The FR235 current pace seemed way more stable; there were definitley less fluctuations. The F5 pace was all over, unless I was running in a straight line for a good distance. I'm not sure which was more accurate/precise, but the FR235 does a better job at smoothing.

After the run:
- I used DCRainmakers anaylzer tool to do the comparison, as well as MyGPSFiles. I also uploaded them to Garmin Connect to see how Garmin viewed the files.
- The FR235 showed a more smooth pace. The F5 has more fluctuations. Again, not sure wihch is more accurate or precise.
- The FR235 did better around corners or under trees. The F5 was often taking corners wide, or short.
- The were both decent at straight lines.

Pace Graph:

DCR Analyzer GPS Maps:
(Fenix 5 is the purple line, FR235 is the blue line.)

I'll do some more runs to compare, but I'll alternate wrists, and I'll also compare the GPS vs GPS+GLONASS.

Thank you for your comparison, i hope you keep us updated. I am very interested in this, unfortunately the f5 is the first GPS watch i own so i don't know what is a realistic expecation in terms of GPS and pace accuracy. So far i did a lot of runs, some of them with a very good tracking, and some where the GPS was way off (50m+). The pace however is very fluctuant to a point where it is just shy of being useless most of the time.

0 _Reinier_ over 7 years ago

Nice comparison. I look forward of seeing more comparisons. I noticed something similar, I was stretching and did not pause my fenix 5. It looks like i was moving around the spot i stretched. This never happend with my polar m400. See screenshot

0 Former Member over 7 years ago

Nice comparison. I look forward of seeing more comparisons. I noticed something similar, I was stretching and did not pause my fenix 5. It looks like i was moving around the spot i stretched. This never happend with my polar m400. See screenshot

This kind of behavior usually happens when GPS accuracy window is larger than traveled distance during recording interval. It begins to hunt around creating a messy pattern. Actually even when moving, your covered distance may be still shorter than what the device can successfully track in a 1s time window. This is what usually creates the wobble in GPS tracks and especially noticeable at slow walking / jogging speeds.

Smart recording interval probably should help with this. Not sure if Garmin even calculates all of the recorded GPS data in the distance data track, even with 1s recording, or is it filtered based on wrist accelerometer data (no movement = distance calculation stops). According to my experience so far the total distance calculated from GPS points is usually a bit longer than what is actually used for accrued distance that is presented in Garmin Connect, especially with 1s recording.

At least this is the experience with my FR235 which is usually very accurate even when the GPS track is not perfect. Will probably soon get a F5 so will see if it's any good ...