Epson Runsense 810-SF 810SF :: GPS + HR Accuracy Review

Epson SF-810 Review

Epson SF-810 ReviewEpson have recently made a significant effort to enter the wellness/fitness markets with a series of wrist-based devices. The RUNSENSE SF-810 is their top-of-the-range running watch. As at April 2015 this is coming in at over £250 (rrp £300)

Summary: It is a great piece of quality-engineered, running kit for more serious runners. It has one of the most accurate optical HR sensors. It has an in-built cadence/stride sensor. It can be used as a watch and the sport usage battery life is just under 24-hours (depending on precise usage). It’s ‘good-to-go’ as it is, you don’t need to buy anything else.

You might and should (IMvHO) at least consider this over and above a Garmin, Sunnto, TomTom or Polar because of the accuracy, battery life and optical HR. It is a real-RUNNER’S watch. If you MUST have optical HR then this is your RUNNING watch.

If you don’t like chest straps, this is probably the most accurate runners watch out there.

It’s not without its problems of course.  It only has 3 metrics per screen, or three plus HR-Zone to be more precise and the tap-screen control is just a tad too sensitive sometimes. The software/hardware initial setup is not great, indeed the only material faults with the watch are not the watch itself but all the supporting software, documentation and procedures that appear to have been cobbled together around it.

Now I’ll be honest. I want to like this product. We all should. Garmin have a very large market share and Suunto and Polar (and TomTom) don’t seem to be making many inroads into it. The financial clout required to enter the market and to do R&D for a whole product range AND for a decent multi-platform APP/software package is HUGE. Many millions. The global market is HUGE and the payback could be profitable. But the investment can never come fro a new start-up. It simply HAS to come from a company with access to lots of cash. Epson is one of the few companies that can do that….


Opening Up and Starting Up

It comes in a standard, average-quality, container and you get a USB charging cradle and the watch itself. There’s a quick-start guide too.Epson SF-810 Review

It’s nice to look at and it compares favourably to other devices in that respect. Here it is next to the Epson PULSESENSE band. The cradle seems a bit bigger than it needs to be and, also trivially, the device is NOT as easy to get out of the cradle as it is with the PULSENSE.

Here you can see a comparable screen size to the Garmin 920XT. Epson could quite easily have fitted in two metrics on the middle line like other round-faced watches such as the FENIX. However the 5x circles at the top of its screen represent HR Zones 1 through 5. So that is a sort-of, extra metric.


Epson SF-810 Rear

On the reverse is the optical HR sensor. It IS DIFFERENT to the PULSENSE. Looking closely the SF-810 appears to have two receiving plates next to the light. Whether or not that is what makes it accurate I don’t know.

Epson Pulsense - rear
Epson Pulsense – rear

For completeness here is the rear-shot of the PULSENSE.

And here they are side-by-side.


Software Setup

I found the software setup clunky and time-consuming to setup. EPSON RUN CONNECT is the software you need to install on the PC and/or as an APP. RUNSENSE View is the software you need to install for viewing the data. You will need a (free) account with fitnesssyncer/tapiriik if you want to transfer data to use any other vendor’s sports analysis software eg STRAVA

I had to speak with Epson support in order to figure out how to update the firmware that it was telling me to upgrade and I had to speak to support in order to figure out how to get HR data out of RUNSENSE as the TAPIRIIK link did not work for me.

Must Read: Polar Verity Sense Review

Most (loan) watches that I receive come with an unused quick start guide. The Epson quick-start guide had been used by previous reviewers. A manual or quick start guide should NOT BE NECESSARY. Everything should be intuitive. The manual is there for reference.

Some of the great Stuff

There is great stuff here. Let’s face it, you will spend VASTLY more time using the watch than setting it up.

Get over that first hurdle that I’ve just moaned about and you will be in running nirvana.

You can set autolap by distance or by time. I often do time based intervals and this is great for me. My more expensive Garmin can’t do that.

The battery life really is good. Up to 20 hours with HR+GPS and up to 24 hours with GPS on but HR off. I never tested those limits, it always had sufficient charge for me. That’s more than the Garmin Forerunner 620.

It has a built-in cadence sensor (for some reason they call cadence ‘pitch’) and stride length can also be shown but I’m not quite sure what could be done about the latter (stride length training).

It has a WALK mode and a BIKE mode but no swim mode. HR alerts, for example, can be used specifically with those modes. It is waterproof to 50m and so you can swim with it (accuracy during swimming further on in this post). However it is A RUNNING watch, not a triathlon watch. The ‘nod’ to these functions suggests that a triathlon watch is perhaps Epson’s next new product based firmly on this form factor.

There are altitude and ascent metrics. But also one called GRADE (ie how steep is the hill). Again, perfect information for a running doing hill work. My top-of-the-range Garmin can’t do that.

TAP-control. Not quite Apple’s TAPTIC engine but the 810 enables a firm tap to be user-configurable. I added the ‘change screen’ functionality as the response to the tap, you might make a tap add a lap. Great stuff

IMG_3529On-screen metrics: 3 horizontal areas are presented with the central one being higher than the other two. This gives a very nicely clear number whatever you have chosen to go there). The number would be bigger that a quarter-screen number on my square-faced Garmin, whereas the top and bottom number would be smaller than the corresponding one on the Garmin. Of course you can also have 2 metrics or a single metric per screen and there are 4 standard configurable screens for use in this way. If the option for 2x central metrics was offered I would have used that, however I suspect that as time progressed I would use the 5x HR zone indicator that is at the top of each screen instead of a specific HR reading. So, overall, that’s a nice compromise and something a little different to Garmin.

Time-to-HR Zone (for current lap): Another interesting metric. Not one that I’d previously heard of. I never actually used it but presumably it estimates how long it will take you to get to your target zone at current effort rates. Again, nice. Probably of limited use though in reality.

The ascent/descent/speed metrics all look useful to add to bike-screens if you ever cycle. However the lack of a BTLE bike cadence and/or speed and/or power sensor is somewhat limiting for more serious bike usage. Perhaps, like Wahoo TICKR-X, some for of motion sensor algorithm for the wrist watch can be used to determine cycling cadence? cycle cadence would be the most basic sensor/metric to add first.

Steps and Lap Steps can be configured as metrics for when in use in WALK mode. However the SF-810 is NOT an activity tracker in the sense that it permanently counts steps and monitors movement constantly. Walk mode has to be specifically turned on and an exercise session started. Personally I think this is a reasonable approach. Having recently done 1,000 steps (with another product) whilst driving I suspect that MANY step counters/activity trackers are wrong. In reality pottering about the house, garden or office is only going to add a few hundreds of steps. Why not measure the walk to the shops or the walk with the dog round the park or the walk to/from home as specific step-activities? Those are measures that are likely to do some (albeit small) amount of good. If you are buying this watch you aspire to being a runner of some sorts. You don’t need to record the steps you do around the house; they are meaningless in your context IMHO. Running miles are FAR FAR more beneficial than walking miles.

Estimated time-to-completion and distance-to-completion metrics are useful for goal-related running activity, which is also supported.

LAPS can be made manually or automatically (distance/time). However there is also the SPLIT functionality which can be used alongside laps. LAPS occur within SPLITS. So you could do a 2×20 minute session with a 10 minute warm up, 5 minute rest and 10 minute cool down. Each 20 minute would be a SPLIT and you could have 1km or 4 minute AUTOLAPS or manual laps within each SPLIT … nice!

Interval functionality is provided, allowing effort and recovery periods all to be repeated. Standard stuff but necessary for a runners’ watch.  Alarms can be set for target heart rates in the active interval. More complex structured workouts with cadence/pace and other alerts appear not to be possible. To be honest many people would not use this functionality (I rarely would do) yet it is an omission that must be corrected at some point. This would score down the SF-810 against other watches on a feature-by-feature comparison, indeed Suunto have only just implemented their rudimentary workout functionality in this respect.


For a runners’ watch the manufacturer needs accuracy. The runner might not really need super-accuracy BUT THEY WILL MOAN ABOUT it all the time. So from a customer satisfaction point-of-view and to limit ‘product returns’, accuracy is rather useful. I would temper that with the accuracy of heart rate and particularly with optical heart rate. I sense that people out there realise that optical and (non-chest strap heart rate) are new innovations and we will all give a little slack in exchange for the joy of not having to wear a chest strap.

Here is the HR track from my Garmin on a test run. Garmin have their detractors and critics but I would point out that this is Garmin’s latest, greatest pod and strap and a new factory reset Garmin 920XT. So it should be accurate.

920XT 13-04-2015, Heart rate

The above track corresponds to what I tried to do. Some quite high peaks and some steady and relatively high states maintained for a minute or a few minutes. It seems about right.

Here is the RUNSENSE HR track. (export to GPX, import with Strava and use the special Strava TCX URL extension to export to TCX and then upload to Sporttracks…easy, sigh!)

Test Data For Watch RUNSENSE 13-04-2015, Heart rateIt looks broadly similar. You can see the flatlines towards the end. I wasn’t aware of those during the session but there they are. It was a hot day, maybe they were produced because of sweat? The only difference I was aware of during the session was that the RUNSENSE HR seemed to take a bit longer to come down after a peak. Looking at the two graphs you might say that the RUNSENSE was a tad lower?

(EDIT: Added comparison graph) Anyway, comparing the two directly we see the two flatlines towards the end and also the inexplicable omission from Epson around 22 minutes where I was running at faster than 3:30/km pace.


This observation is borne out in the TRIMP score. I won’t bore you with what it is. Basically the  Garmin is 69 and the EPSON 67. That’s not ideal but I could live with it. Most likely the difference is caused at the flatline periods.

Either way the RUNSENSE is acceptable. I could live with it and no doubt further improvements are on the way. Other optical HRs I have used don’t properly work at all at the higher heart rates…that (the other vendors) is NOT acceptable for a runner.

GPS Accuracy

Here are two example on the same course of me running in the EXACT middle of the road for the entire distance shown. You should be aware that the map may be wrong in the sense that the GPS position inherent to the map could be out slightly. This will further compound any inaccuracy from the device. But at least the map will be as equally inaccurate for both devices…

The first example is running in totally clear sky with no building or trees in a curvy line, probably over a km or so.

The first is the RUNSENSE and you can see a shift to the EAST and SOUTH. I’ve experienced similar with other watches in the past but, if the map is right, it’s a good 5m out.

pulsense - curve line tracking

The next is with the Garmin.

920XT - curve line trackingYou can see it’s different with a bias towards the WEST.

Neither look great! Maybe the Garmin edges it? But I’d probably call it a 0-0 draw.

Let’s look now at straight line accuracy with some tree cover (a tree-lined path with not too many leaves out at this time of year). The satellite image had the tree cover from whenever it was taken so I’ve used a map view from the same map provider.

You’ll probably have to look at this one, it’s the RUNSENSE.

Runsesne - straight line tracking

And here is the Garmin.

920XT - straight line tracking

Again I was running down the GREY TRACK in the exact middle for about 1km. Ignore when I was running from right to left (above) over the grass. Garmin wins this one 2-1, I’d say. But the Epson produces a straight line and so, in theory, the speed/pace that comes from that should be accurate as I was running in a DEAD STRAIGHT line. So even though the Epson was positionally out the PACE/SPEED might be as-accurate or more accurate. So I think Epson has just scored a last-gasp equalizer and so we move into extra time…

Here are some splits from the same run from the EPSON RUNSENSE. As I said earlier I tried to run at a range of PACEs over reasonable periods.

runsense Pace Splits

And the same splits from the Garmin 920XT, there are trivial differences in the lap positions, I could only press one at once and you can see the split times are similar. In any case I had to add the splits for the RUNSENSE manually for reasons that I won’t go into now.

920XT Pace Splits

So the Garmin has me running 50 or so metres further in total. That seems broadly consistent across the splits.

However this data comes from Sporttracks. Sporttracks and other software will most likely re-calculate the PACEs based on the GPS coordinates and time splits. So both of the two tables that I have just shown may, in fact, bear little correlation with what the watch actually showed when I was running. And, to make matters worse, on the Garmin the algorithm for the CURRENT PACE and for the LAP pace are both different.

My sense from the run was that the Epson had me running FASTER (ie a lower pace number). But this is NOT borne out by the data. My sense from other runs with the Garmin (previously) was that the PACE data in Sporttracks always seemed faster than what I remembered on the run (and I use LAP and INSTANT paces ALL the time)

So I’ll let you draw your own conclusions from that. (Maybe the Garmin shows up slow?)

If it’s consistent then you can use it and it shouldn’t matter much. But you might then argue that you need to run at a certain pace to hit your 5k or marathon time and I would agree with that. But then you used to use the course lap markers (could be 2-50m out, easily). And you might not run in a straight line and that too can easily cost you 50m of extra running over 5k.

Here are the paces as a bar chart. Not sure that helps either.

Runsense first.

Test For Watch RUNSENSE 13-04-2015, Pace

Garmin second

test for watch - 920XT 13-04-2015, Pace

There was an AUTOLAP event on the Garmin which might probably explain the one bar that is different.

So I’d say both are OK to use.

Accuracy When Swimming

Here is the data from a slow swim in a nearby outdoor 50m pool. As you can see the HR records perfectly well and indeed arm strokes are recorded too.


The speed from the GPS will be meaningless and as you can see there are cut outs on that as the device goes under water. The strides per minute (strokes per minute) figures look a little suspect as my stroke rate is a little on the slow side, especially in this slow swim. But the HR track comes up accurately with no drop outs.

Contrast that to DC Rainmaker’s experience below with an open-water swim. Maybe there have been firmware improvements since he tested his before general-release?

Anyway, it’s not (yet!) a swim watch.


For starters there’s none of the SMS notifications stuff. This is a proper runners’ watch.

I won’t go into the details of the software. IT has a different look and feel to the (actually OK) PULSENSE software and the APP and PC/WEB interface have a different feel with the APP having a much nicer feel than the not-so-great PC/WEB interface.

You can certainly get by with the stats from what EPSON offer you. However if you want more, and I would certainly want more, then you MUST get the data out of the Epson environment.  You can only export in CSV (useless) or GPX (very limited) formats. The other alternative is TAPIRIIK which I couldn’t get to work. (EDIT: May 2015 – Epson have now linked to STRAVA and have also worked on TAPIRIIK)

Here are some Epson-sourced images showing the software

Best REI/Wiggle/PMC price is linked to. Prices are often discounted below $/£/Eu100.


This watch is just about correctly priced for a high-end, accurate, optical HR+GPS runners’ watch with excellent (Apr 2015) battery life that wants to give the correct value for money. To do well in the market, however, it should be priced lower in order to get over the ‘it’s not-a-Garmin’ barrier and to compensate for an inadequate software offering around what is obviously an excellent watch.

The two actions that Epson need to do NOW are

  1. Improve data sharing/connectivity
    1. Get the TAPIRIIK link to work robustly
    2. Allow manual .FIT or at least .TCX export (EDIT: May 2015 link to STRAVA Supported, GPX export is there too)
  2. Lower the price significantly to £150 (note that I have already said it IS correctly priced already) make this already excellent watch SUCH good value for money that people HAVE to buy it without a second thought. Shake up the market. (OK It’s not going to happen!)

With Garmin’s entry into the optical HR market (May 2015), Epson need to move fast.

Watch: 9.5/10

All the non-watch stuff: 3/10


Here is the 90+ page manual. The Garmin 920XT has a 3 or 4 page manual and many more complexities across all triathlon sports.


Here is the iOS manual which is different and, in places, better !!

Prices, Discounts & Availability

Best REI/Wiggle/PMC price is linked to. Prices are often discounted below $/£/Eu100.

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