Garmin 945- Worthy Successor for a TomTom Sparks 3?


My first GPS watch was a Garmin Forerunner 305. I was very excited to be able to see pretty much exactly where and what distance I was running- and thus, how fast.

My first GPS watch: Garmin 305

Then I bought a TomTom Cardio + Music watch. I was hoping I would have not have to use a chest strap anymore because the watch had an optical sensor that was supposed to measure the pulse on the wrist. Unfortunately, that never worked well for me, so I got a bluetooth chest strap that I could couple to the TomTom. I was also hoping that I could listen to podcasts from it during long runs. That did not work well either, because I had many drop outs.

However, it was smaller and more comfortable to wear, and most importantly- it was waterproof, so I could swim with it. There is no open water swim setting- but I could use it for open water swimming in „Freestyle“ (literally!) mode. It would not be able to measure the distance I was swimming exactly, but I could see roughly were I was swimming.

My first TomTom watch got lost during a travel, so I bought a TomTom Sparks 3 (this time without the music- promise) – with which I have been quite happy. With an overpriced bike-mount it even worked very well for me as a bicycle computer.

My TomTom Sparks 3 with an aftermarket wrist strap, the original wrist strap to the left and the overpriced bike-mount to the right.

Now the Tom Tom Spark 3 has become outdated, too (and Tom Tom decided to discontinue the development of GPS watches). Now there are much fancier gadgets available.

If I am really honest to myself there was no real need for me to get a new GPS watch. Yet I know being able to use new technical toys is always very motivating for me. So when I signed up for a popular half-marathon I used this occasion as an excuse to buy a Garmin 945.

Some Test Results

After the purchase my first questions were: will the optical wrist-sensor work for me, and how well will it track my position during outdoor swimming.

To see how well the optical heart rate sensor works, I was running, biking and swimming with the Garmin 945 and a Polar H10 chest strap as a reference. For running and biking the results were pretty good; though once when I did some interval runs I noticed a bigger discrepancy. Maybe it was my fault, maybe I had the wrist strap to loose or too tight.

During this run there was a very good agreement between the optical sensor readings of the Garmin 945 and the readings of the Polar H10 chest strap.
Some intervals where the Garmin 945 sensor did not catch the heart rate frequency increase correctly.

Optical heart rate sensing during swimming is available after the software update from September 2018. However, at least on my wrist and during my test swim, the reading had nothing to do with my heart rate. Perhaps the sensor picked up the hear rates of nearby fish or birds.

Heart rate during a swim: the data from the Garmin is way off

To find out how well will the Garmin 945 will track my position during outdoor swimming, I was swimming in a nearby lake with the Garmin on my left wrist, the Tom Tom on my right wrist and an iPhone 6s (with the Polar App running) in a swimming buoy.

I was hoping I could use the GPS data from the iPhone as a reference. However, the path that the iPhone recorded was just as wiggly and unrealistic as the data from the Tom Tom. However, the track that the Garmin recorded looked very smooth and seems to correctly show the path I was swimming.

Swimming with the Garmin and the TomTom on my wrists, and an iPhone in a swimming buoy. I was hoping I could use the iPhone data as a reference- which obviously did not work out. The track from the Garmin 945 looks pretty realistic.

So I went for another swim, and this time I put the TomTom into my swim cap. This actually worked well- I got nearly identical readings from both the Garmin on my wrist and the TomTom in my cap. Which probably means that the Garmin on the wrist can correctly trace my open water swimming (at least it could during this swim in a lake without any waves). Impressive!

Swimming with the Garmin 945 on my wrist and the TomTom in my swimming cap. Nearly identical tracks- which means both are probably correct.

Some Other Features

When the Garmin 945 is worn at night, it acts as a sleep tracker (so does the TomTom, but I did not use it for sleep tracking because it was too uncomfortable).

I have been using a Withings sensor below my mattress for a while for sleep tracking. Like the Garmin, it senses motion and heart rates and tries to infer sleep phases. I find sleep tracking useful because actually seeing „bad“ data makes me think about it- did I not sleep well because of too much coffee too, too much alcohol, too much food or because of unsuitable entertainment before bedtime… and thus, sometimes helps me to avoid such factors and thus actually improved my sleep.

Sleep tracking data from the Garmin 945 on my wrist and from the Withings sensor below my matress. Detected sleep duration was about the same, but the Garmin thinks my deep sleep was in the first half of the night- which is more realistic.

A feature I was keen to try out was the „music“ feature for listening to podcasts during long, slow runs. It worked really well with my „Antimi“ truly wireless headphones. No dropouts at all!

„Music“ feature: I experienced a pleasantly stable connection to my bluetooth headset

The Garmin 945 can show a map and supposedly it can be used for navigation. I do not yet know if this will be of any use for me- the screen is small, and using the map feature seems to be incredible complicated, as it involves a lot of button-pressing. Perhaps the simple trail feature of the TomTom is more useful.

The map is very fancy, but to me it seems be very difficult to use

Preliminary Conclusion

During the first week of using the Garmin 945 I was exercising quite a lot- so far the motivational new-toy-effect has worked for me.

My first week of using the Garmin 945

I do not think that I will regret that I bought it. Sure, my trusty old TomTom does everything I really need a GPS watch to do. But now I do not have to take a phone with me when I want to listen to podcasts during running.

And most importantly, a fancy sports watch like the Garmin 945 will surely give me more prestige in my social peer group than a Rolex would 😀

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