Why You Can Trust CNET Epson Runsense SF-810 review: Long battery life and impressive accuracy can't overcome the high price
The Runsense SF-810 has superior battery life and impressive GPS and heart-rate accuracy, but a high price will have you running for the hills.
As he approached the final stretch in the Boston Marathon, Olympic silver medalist and last year's champion, Meb Keflezighi, looked down at his wrist and with a quick glance was able see his pace, distance and time. He could even monitor his heart rate, even though he wasn't wearing a chest strap. Keflezighi was wearing a GPS running watch, but it wasn't a Garmin, a Polar or a Suunto watch, it was one from Epson, a company known primarily for its printers and scanners.
Epson Runsense SF-810
The Good
The Bad
The Bottom Line
The company has introduced three models as part of its line of Runsense sport watches that it hopes can compete in the crowded wearable market. There's the entry-level SF-510 ($250, £160, converted to about AU$325), the midrange SF-710 ($280, £200, converted to about AU$365) and the high-end SF-810 ($350, £260, converted to about AU$455), which is the model we reviewed. All three watches share many of the same features, but only the SF-810 includes a built-in optical heart-rate sensor.
Being able to run for longer distances without a charge, and keeping excellent heart rate tracking, are key features that make any running watch better. But in a super-specialized landscape like GPS-enabled running watches, there are only so many who will find these features appealing in exchange for its tradeoffs.
What it does
Epson's Runsense watches aren't activity trackers or a smartwatches. The SF-810 and its siblings are GPS-equipped running watches. All three models are capable of tracking pace and distance, while the SF-810 is also capable of measuring your beats per minute thanks to the optical heart-rate sensor on the back.
Unfortunately, as the name implies, these watches don't have multiple functions and are designed solely for runners. There is no specific mode for swimming or cycling, although you can still measure speed and distance on a bike when the GPS is enabled. This is done through the normal running mode.
Despite an included accelerometer, the Runsense watches don't measure steps taken, distance walked or calories burned throughout the day. Instead, the accelerometer is used mainly as a GPS substitute to measure distance when GPS signals are unavailable, such as when running indoors or on a cloudy day when you can't acquire a signal anywhere.
Indoor runs were only off by around 0.10 to 0.20 mile, versus what my treadmill measured. This is similar to other devices, such as the Garmin Vivoactive and Polar M400 , when measuring distance with their accelerometers. I don't rely on the watch much when I am inside (that's what the treadmill's distance reading is for), but the accelerometer helps insure you're covering your distance measurements in any condition.
Design
You wouldn't want to wear the SF-810 around all day, even though you most certainly can. It's lightweight, and the strap design, which features a spring-like mechanism, makes the watch comfortable to wear. But anyone outside of the running crowd would likely be turned off by its bulky body. The SF-810 functions like a normal watch, displaying the time and date, but it lacks any all-day activity tracking: you'll only see data get recorded when you track runs, which eliminates it from the "I need a Fitbit" crowd.
Aside from charging it, there isn't a real need to take the watch off. It carries a water resistance rating of 5 ATM, which means it can withstand pressure of up to 50 meters and can be worn in the shower and pool. You can learn more about water resistance ratings in watches and activity trackers here.
What stood out to me was the display. There's no fancy touchscreen or high-res colors: it's a basic LCD. But it's always on, and it's easy to read outdoors, even while in direct sunlight. Running at night was even possible thanks to the impressively bright backlight, which illuminates the display for 10 seconds at a time.
Heart rate: No chest strap required
A heart-rate monitor makes it easy to measure, monitor and control the intensity of your workouts. It also opens the door to heart-rate interval training. The problem, however, is that the chest straps traditionally used can be quite uncomfortable, so much so that many runners choose not to wear them.
The big appeal of the SF-810 is the optical heart-rate sensor that sits on the back of the watch. The technique used by Espon is similar to those found in the Fitbit Surge , Apple Watch and Mio products, however it is developed completely in-house. A flickering LED green light is used to light the capillaries, which allows the sensor on the back to measure the blood as it flows by.
There's a belief that chest straps are more accurate than the optical sensors on wearables. I tend to agree with this statement, but that was until I tested the SF-810. I wore both the SF-810 and a Polar M400 connected to a Bluetooth heart-rate strap to see how they stacked up.
The SF-810 delivered impressive results that were, for the most part, equal to that of the Polar chest strap. The only difference I noticed was that the chest strap was quicker with the readings, and, on occasion, the SF-810 would need a second or two to get the correct number.
Overall, though, I was impressed with Epson's in-house heart-rate technology.
GPS inconsistencies
The biggest issue I had with the SF-810 had to do with the GPS, the one feature runners care and rely on, but it had nothing to do with accuracy. In fact, the GPS accuracy was on par, if not better than the Garmin Forerunner 225 and Polar M400. The issues I faced surfaced when it came time to acquire the GPS signal.
On my first day with the watch, I stepped outside my apartment building in the Upper East Side of New York City. I waited as it searched for a signal...and waited and waited. Around the two minute mark, the watch told me it was unable to acquire GPS. I had the option of trying again, skipping (which would continue the search as I began my run), selecting indoor mode (which disables GPS), or canceling the workout all together.
I chose to try again. I wasn't in a rush and luckily it was a nice day out, but if this had been the dead of winter, I would have very unhappy. The mission failed. I ran without the GPS on the first day.
On the next run I decided to use Epson's assisted GPS feature. This will preload your location to the watch through the company's mobile app. It took about 25 seconds to get a signal, then I was off and running. The problem with this solution is that the precache location will only remain on the watch for two hours. It can be a pain to have to do this before every run.
My GPS inconsistencies continued over the course of the next two weeks. Some days it wouldn't acquire a signal with the assisted GPS feature turned on, and other days it would be fine without it.
I frequently begin my GPS search as I run toward Central Park. The Garmin Forerunner 225 and Polar M40 usually pick up a signal before I reach the entrance, which is less than half a mile away from my apartment. The SF-810 always seemed to have difficulties locking in on my location as I ran. It wasn't until 20 or 30 minutes into my run that a signal would finally be acquired.
The SF-810 also had trouble mapping out direct routes on the streets of New York City, but this is a problem seen in watches from Garmin and Polar, too. It's an urban problem. The GPS was usually spot-on once I reached an open area, such as Central Park or along the East River.
There's a general rule of thumb when it comes to GPS watches: on cloudy days, you will have a more difficult time acquiring a signal. The SF-810, however, would succeed on cloudy days and fail under the clearest of skies, and vice-versa. I frequently wore a Garmin Forerunner 225 or Polar M400 during my testing with the SF-810 and didn't once experience a problem with acquiring a signal with either watch.
Running with the SF-810
When I wasn't encountering GPS-acquisition problems, running with the SF-810 was quite enjoyable. The watch is fairly basic. There are no complicated menus that you need to search out before starting a workout. Simply press the start button, wait for a signal, and press the button one more time to begin tracking.
What I liked the most was the amount of data the watch manages to present. The SF-810 features 35 different data points and four customizable display screens. You have the option of displaying one, two, or three lines of data points on each screen at once.
What can you choose to display? A lot: distance, lap distance, pace, average pace, lap pace, speed, average speed, lap speed, split time, lap time, time, calories burnt, altitude, guide time, guide distance, stride, average stride, lap stride, pitch, average pitch, lap pitch, heart rate, average heart rate, max heart rate, lap heart rate, steps taken during run, lap steps, heart rate zone time, time to heart rate zone, total ascent, total descent, grade, estimate time, estimated distance and target pace. Take your pick.
You can also tap on the screen to switch between the different display screens, making it simple to switch between each display midrun. It's great, but sometimes I noticed I had to tap pretty hard.
As with a majority of running watches on the market, the SF-810 includes both Auto Pause and Auto Lap features. Auto Pause automatically pauses the watch when you stop (for example, at a busy intersection), while Auto Lap automatically records lap data when you reach a specific distance. There's also interval training on board. You can set the amount of reps you would like to do in a given running workout, along with the time, distance and heart-rate zone, and amount of rest.
I generally try to stay around an eight minute pace on my runs. With the SF-810, there's a target pace feature to tell you when you need to speed up or slow down to hit that specific pace. You can also set up a target pace range. For example, if I set my range as 15 seconds, I won't be notified to change my 8-minute pace as long as I remain within the 7:45 to 8:15 range.
Epson's Run Connect app needs work
Basic data from your runs can be viewed directly on the watch with a tap on the Lap button. To get a more detailed look, however, you will want to upload the data to the Android or iOS mobile app, or Epson's website, which I found I used more often than I expected to view my data.
The Epson app, unfortunately, is of the worst things about using the SF-810. Not only is the upload process slow and unreliable, but the app interface is full of frequent loading delays. Epson's Runsense website is faster and delivers a slightly better experience, but it's not all that great either.
The SF-810 doesn't include automatic syncing, either. Watches like the Garmin Forerunner 225 and Vivoactive are capable of automatically uploading data from your runs once you are in range of your smartphone. But with Epson's watch, you have to press and hold the Lap button to initiate sync. Then you have to manually upload each workout through the app. It's tedious and time consuming: I sometimes waited more than five minutes for it to finish.
Once everything has been synced, you can view a map of your running route, and charts with data on your heart rate, pace, distance, and more. The Run Connect app is also where you can customize your watch features: display screens, toggle features like Auto Lap and Auto pause, and activate Assisted GPS.
Battery life
Epson's entire Runsense line offers some of the best battery life in the business. The SF-810 does especially well, lasting 20 hours with an active GPS signal and active heart-rate sensor. This is compared to 10 hours of battery life with a continuous GPS signal and heart-rate sensor on the Garmin Forerunner 225, 5 hours on the Fitbit Surge, and 9 hours with the Polar M400 and a Bluetooth heart-rate monitor. The cheaper SF-710 and SF-510, which don't include heart rate, are said to last a whopping 30 hours with a continuous GPS signal.
I got about two weeks of overall usage out of the SF-810 before I was required to charge it. During this time I used the GPS and heart-rate sensor for around 30 to 40 minutes, four to five times a week. Your results will vary based on how often you use the GPS. It's a good thing I didn't need to charge much: the mammoth-sized charging cradle is a pain to carry around.
Conclusion
The Runsense SF-810's heart-rate sensor and GPS tracking is incredibly accurate. The amount of data the watch can track is impressive, battery life is very good, the display is easy to read, and it's comfortable to wear. But its GPS-acquiring problems, weak app, lack of automatic syncing, and low data uploading make it a real headache to use.
The last major hurdle is price. At $350 (£260), the SF-810 is $50 (£20) more expensive than the Garmin Forerunner 225, which also includes an optical heart-rate sensor plus all-day activity tracking. Epson priced the SF-810 towards the high end of the market. Long-distance elite athletes such as Meb Keflezighi might appreciate it, but for everyday runners and fitness-tracking folk it won't hold much interest.