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Epson Runsense SF-810 review: Long battery life and impressive accuracy can't overcome the high price

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MSRP: $349.99

The Good Accurate heart-rate and GPS tracking on runs. Long battery life. An easy-to-read display that offers up a lot of data. Can be worn in the shower and pool.

The Bad No all-day activity tracking. Workout data isn't synced automatically. Mobile app is slow. GPS signal acquisition slow and inconsistent.

The Bottom Line Long-distance elite athletes will appreciate the accuracy of the GPS and heart-rate, but the high price tag makes it less appealing for everyday runners.

Visit for details.

6.7 Overall
  • Design 7
  • Battery 9
  • Performance 6
  • Software 4
  • Features 7

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.

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.

Sarah Tew/CNET

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.

Sarah Tew/CNET

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.


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.

Sarah Tew/CNET

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.

The Runsense SF-810 compared to similar running watches. From left to right: Runsense SF-810, Garmin Forerunner 225, Fitbit Surge, Adidas MiCoach Smart Run. Sarah Tew/CNET

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.

Sarah Tew/CNET

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.

The heart-rate data recorded on the Epson Runsense SF-810/ Screenshot by Dan Graziano/CNET
The heart-rate data recorded on the Polar M400 using a Bluetooth chest strap. Screenshot by Dan Graziano/CNET

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.

Sarah Tew/CNET

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.

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