What about the temperature ?

Garmin, for reasons unknown to us, didn't integrate support for the Tempe so third party developers had to come to the rescue. There's more than one app to read the Tempe but I've found Tempe Visualizer OK (until the 1040 arrived).

I've also been doing some temperature comparisons on what was a mainly sunny morning. 

This photo shows the location of the devices (1040, 530 and Tempe). It's possible that the silicone case I put on the 1040 (a modified 1030 case) because I dropped the 1040 on it's first excursion (slippery edges) reduces the amount of air cooling.The Tempe is on the underside of the stem where it's mainly sheltered from the sun and gets a bit of wind when the bike is moving:

The top three rows in the graphic below are for the Edge 1040 (including the reported temperature) and the bottom 5 are for the Edge 530 (including both the reported temperature and that measured by the Tempe (which includes a +2C correction which I've found gets it correct in cold and cloudy conditions with no solar heating)). It's clear that the Edge 1040 fluctuated most and the Tempe fluctuated least. However, I think the Tempe is only read once every 5 minutes so it may miss the extremes.

It was also noticeable that the highest temperatures on the Edges were when I was cycling uphill in the sunshine when there would be minimum air cooling.

After the ride I left the bike, with the devices, in the shade for 1/2 hour, and then did a very short ride so I could log the temperatures. All three devices recorded 22C at the start of that ride which is very close to the ambient temperature at that time.

If logging fairly accurate temperature matters then using an external sensor placed in a shaded location is the only solution.

Nice analysis. the position on the 3 computers, differing mounts update frequency on the tempe and the case on the 1040 means this is not a direct comparison, but about as good as you could do. i think 1.5c difference in this scenario is ok. The fact all 3 show the same temp in the shade shows that that software and sensors are likely the same. It's down to the position on the bike. Most people go out front mount, in the wind.

Thanks for all that information. I have ordered a Tempe.

I received my Tempi but it will not pair with any of my Edge devices. Is there anything I need ti do beyond the normal pairing procedure? The battery is installed correctly. The battery voltage is 3.25 VDC. I have restarted the Tempi.

johndonaldsom said:

I received my Tempi but it will not pair with any of my Edge devices

forums.garmin.com/.../1437331

I recall there is no pairing process. Once the app is installed add a Tempe data field (listed under Connect IQ). It may take a few minutes for a reading to appear after starting a ride. I think the Tempe only broadcasts a value every few minutes. There are some options which can be accessed using Garmin Express. The two options I use are to write the data to the fit file and have a 2 degree (units not stated) temperature offset.

PS: I've just done a trial installation of Tempe Visualiser on the Edge 1040 as it claims to be compatible. The process I described above works and I got a plausible number in a data field. However, I've uninstalled it as the Varia radar wasn't connecting which I assume is part of the sensor problem with the Edge 1040. Both radar and Tempe work concurrently on my older Edges and I'll try again when Garmin claim to have fixed the sensor problem.

Thanks again. It worked just as you described.The cloud cover on today's ride was 100% so it was not a good test but when I got home the Tempe was reading 1F above my home weather station which, as you described, can be offset in the Tempe Visualizer. I uses a n Edge 1030+ with the Tempe mounted under the stem. I hope it is not too long before Garmin overcomes their challenge with 1040 sensors and CIQ data fields. 

I used my 1040 for the first time today and was surprised to see it registering 38C at one stage. The maximum for my ride between 14:00 - 16:10 CET was 41C.

I have done similar rides/times over the last week with my Edge 1000 at max. of 36C. Those rides felt a lot hotter than today, much more sapping. I think the 1040 (based only on one ride) is off, 40+C are killing temperatures.

PS: my wife was on the road at 15:30 in the same area and her Fenix 5s Plus was registering a max. of 34C. This was about the same time I had my 41C. Something is definitely not right.

johndonaldsom said:

ech support told me the 1030+ temperatures were “by design”. Shame on Garmin.

Without indicating a reason, this excuse is meaningless. It’s a “non-answer” (aka BS-ing).