Hot
- Wrist-based heart rate monitor
- Download up to 500 songs and connect with BT headphones for phone-free listening
- Sync music from streaming services for listings offline (e.g. Spotify)
- Records a variety of standard and customizable activities
- Performance monitoring and conditioning data
- Broadcast HR to other devices (e.g. Garmin Edge)
- Stylish, sleek and low profile
- Set to block messages/alerts during certain times (e.g. sleep hours)
- Buttons, not touchscreen – easier to use with gloves
- Auto uploads to a variety of apps (e.g. Strava)
- Fully charges quickly
- Links with Garmin Connect for an abundant of data
- Garmin Pay™ contactless payment solution lets you pay with your watch
- Customizable watch face
Not
- Bluetooth range not as good as my Forerunner 920XT
- Requires USB cable with unique charging clip
- Not for multisport (triathlon) or open water swims
Price: $449.99 USD (no music version $399.99)
Source: Online or retail
Colors: Black with Stainless HW, Cerise w/stainless HW, Black w/slate HW, Black w/Rose Gold HW,
Display size: 1.2” diameter
Weight: 42.2g
Connectivity: Bluetooth, ANT+, Wi-Fi
Battery Life: Up to 7 days in smartwatch mode; GPS mode without music up to 14 hrs; GPS mode with music up to 5 hours
How obtained: Sample from company
RBR advertiser: No
Tested: 5 months
Chock Full of Features
I have been using the Garmin Edge 1000 and Forerunner 920XT for years now. My only complaint was having to wear a heart rate monitor chest strap. It was especially an issue when swimming or biking in cold weather as the strap retains moisture. Then Garmin released new Forerunners with both wrist HR and music. Back in March when I requested a test model, the triathlon multisport watch did not have music yet, so I opted for the 645 Music model. It would do everything I needed, except open water swims (OWS).
Transitioning from the 920XT to the 645M was fairly easy. The buttons were in different locations but worked similarly. Garmin has made real strides in reducing the size and weight of their wearables. I really liked the sleek and lighter weight profile of the 645M (42.2g) over the 920XT (62g).
Like many RBR readers, my activities include more than just cycling. The 645M has built-in activity profiles for common sports like running, cycling, swimming (pool), elliptical, paddle sports, and strength training to name a few. You can also create your own. For example, I created an activity profile to record my Pilates and Barre workouts since there was only a choice for yoga.
There are so many features to the 645M it’s difficult to list them all in one review. Therefore, I’ll cover what I believe to be the key ones. For a full listing of the 645M’s specs visit the Garmin site here.
Phone-free Music
If you like to workout to music but hate having to carry your phone with you, the 645M lets you listen via Bluetooth headphones. It stores up to 500 songs including playlists from select music streaming services as well as your own collection. I downloaded songs from Spotify and then paired my Aftershokz headphones. Not carrying my phone was nice and I just used the buttons on the 645M to control playlists, pause, volume, repeat, skip or shuffle. If you have multiple headphones, you can pair them to the 645M and quickly select which one to use.
Garmin is adding compatible streaming services all the time. Currently Premium subscribers can use:
- Amazon Music
- Deezer
- iHeartRadio
- Spotify
You can also pair the 645M to a Bluetooth speaker to hear music. Note, the watch itself does not have a speaker, just the audible tones when receiving alerts or pushing the buttons.
Pairing Sensors
The 645M pairs with Bluetooth and ANT+ sensors, thus compatible with most speed/cadence, HR and power meters. Since I always wear a watch, I liked having the option not to wear a HR monitor during an activity and just use the Broadcast HR feature on the watch. For cycling, I just paired the watch with my Edge 1000, broadcasted my HR from the 645M and my Edge 1000 displayed my HR. The HR broadcast also worked to control my Wahoo Headwind fan. Another use for broadcasting HR was during my open water swims (OWS). I could now record my HR for pool swims using the wrist HR, but for OWS, I broadcasted the HR to my 920XT. Yes, for this scenario I wore 2 watches which isn’t ideal. But I’m not ready to invest in a 945 just yet since my 920XT works just fine
Garmin Connect™ Via Web or Smartphone App
As with other Garmin devices, you can sync to Garmin Connect to store your activity data and join an online community. I really like the mobile app and having my data at a glance. The wrist HR provides sleep data, avg resting HR, stress level, calories burned during the day (not just during workouts) and steps.
This data is important for keeping tabs on how my body is doing not only under the stress of a workout, but during recovery time. I monitor my sleep and when I feel refreshed, I can see how much deep sleep vs light sleep I had that night. Then adjust my rest/sleep time accordingly.
Navigation and Training
Courses can be sent to the 645M using Garmin Connect. Use saved courses to follow a route or try to improve performance from a previous ride/run. Other training features include workouts, Virtual Partners, racing against previous activities and more. There’s even a metronome that you can set to beats per minute to help improve running, swimming or biking cadence.
Performance Monitoring
The 645M monitors your training and recovery by evaluating recent exercise history and performance indicators. Some of the key fitness measurements include lactate threshold tracking and fitness load/recovery.
Garmin Pay™
If you like to use Garmin Pay contactless payment solution, the 645M has this feature. It lets you to use the watch to pay at most registers without carrying cash or credit cards. I don’t use this payment method, so I did not test this feature.
Smartphone Features
Once the 645M is paired with your smartphone (Android or iPhone), you can set up alerts including email notification, texts or calls. If you don’t want notifications while working out, simply turn off the feature.
Battery Life
According to Garmin the 645M battery lasts 7 days in smartwatch mode, up to 14 hrs in GPS mode without music, and up to 5 hrs in GPS mode with music. From my experience those figures are pretty accurate. When charging, the phone requires USB cable with unique charging clip (comes with the watch) and charges extremely quickly.
Other Features and Customization
Using Connect IQ™ store, you can personalize the 645M by downloading apps, widgets, watch faces and more. To test out the customization feature, I changed the watch face to a picture of my cat. Okay, okay, I know it should have been a pic of my bike.
When staying in a hotel, I use my watch as an alarm clock. But it was disruptive to have notifications and alerts going off all night. Instead of removing the watch, I set the Do Not Disturb feature to occur between 10:30 p.m. and 7 a.m.
Like many of the Garmin products, the 645M also has built in safety and tracking features. Simply set up your emergency contacts and pair your smartphone, just hold the light button down and it activates a message with your real-time location. The incident detection feature automatically sends a message to emergency contacts if an incident is detected during an outdoor walk, run or bike activity.
Some of the compatible Garmin devices for the 645M include the Varia™ Rearview Radar, Varia lights, VIRB® 360, VIRB Ultra 30 and Running Dynamics Pod.
The 645M reads outside temperature during activities. Unfortunately, if it is cold outside and you’re wearing long sleeves, it will not get an accurate reading. This isn’t a biggie, but thought I’d point it out.
The 645M uses Garmin Connect to store your data. You can also sync it with other apps like Strava, so activities automatically upload. You can also download Strava segments to the 645M and leverage Strava Live Segments for real-time updates on achievements when you ride. You’ll receive notification of approaching segments, comparisons to your personal best times, to friends’ times and current KOM/QOM.
In March, RoadID announced their new sidekick identification badges that attach to the watch band. It fits nicely on the 645M band and keeps ID information available 24/7. Now I don’t have to remember to put on my ankle strap before a workout.
Bottom Line
Garmin has made great strides in their wearable line making them lighter, sleeker and more stylish. The Forerunner 645 Music with a wrist HRM has tons of features that will monitor your training and performance, provide music and Podcasts during your workouts, and keep you safe with tracking capabilities. With so many features, there’s something for every athlete.
I love my Garmin Forerunner 935 for its battery life (“up to 24 hours in GPS mode”), button-based operation, ability to set up activities, tailor the display screens for each of them, and lots more, When I recently used it on a 3-day, 170-mile tour, charging was only needed once during that period. I typically charge it roughly once/week. I’d say the real-life GPS mode battery life is about 15-20 hours. While the 935 doesn’t have internal music storage, it works very well with the music (entire library!) stored on my phone. And the phone’s with me anyhow. BTW, the 935 is generally considered to have all the capabilities of the much more expensive and heavier Fenix 5 model.
The optical heart rate monitor works pretty well. It’s not as accurate as a chest strap or similar that could be added, but good enough for my use. The Garmin Connect app on my phone works well for keeping track of everything with long-term records, and has neat overlay capabilities within a given event’s records. The Garmin cadence sensor integrates well. Can’t comment on the speed/distance sensor since my dog munched that one before it could be installed – the only thing of value she’s chewed.
I’ve tried some custom watch faces, but they seemed to drain the battery a bit faster, while not providing sufficient advantages over the built-in Garmin variations with their own customization. The buttons become quite intuitive after playing with them a bit when the 935 was new.
I previously owned a Garmin Vivoactive 3 watch for several months that claimed to have up to 14 hours of GPS time, but never came within half that time when used on bike rides. It was obvious that it would not be useful for even a single all-day ride. And the touch screen, which seemed like a great idea, became very frustrating. Gotta love REI’s return policy, which is 90 days for electronics like this.
Maybe the 645 is better about meeting the predicted battery life, but I’d be cautious.
DCrainmaker has very comprehensive reviews for items like this that are worth checking out.