I took my Edge 200 out with me this morning to track a training run.

According to the Garmin I covered 10.4 miles but according to the gmap-pedometer site I covered 11.4 miles. My time suggests that the Garmin is less accurate 😉

I’d expect there to be a small difference (100 yards or so over that sort of distance) but a mile seems to be rather a lot to me.

I’ve previously compared my Garmin it to a friend’s Iphone 4s running Endomondo and they were both within 50 yards of the same distance over 27 miles.

Are Garmins designed for cycling less accurate at slower speeds?

So, how can I check which is right?

I can’t drive the route as much of it was on footpaths.

Yes I have found the same. A friend has the Garmin , orange coloured wrist device and when we do an average of say 15 miles there is at least a mile difference. If you look at his strava route it is definitely much more accurate. Also found the Iphone is also more accurate as long as it retains its signal.

Have found this myself after I uploaded a ride to compare it to friends Strava traces so I did a bit of investigating and there are a couple of settings changes you can make (at least on my Oregon 450, not sure about the Edge). Firstly check what GPS type you are using, on mine there is a setting called WAAS/EGNOS that is supposed to be more accurate. Secondly you can change the recording interval (it’s under ‘Tracks’ on my unit) mine was set to 0.05 miles so I have changed it to 0.01 miles, this uses more memory but hey ho. So far it looks to worked but it was the first time out today since I made the changes.

Thanks for the info chaps, it’s good to know that it wasn’t just me 🙂

I’ll look at altering the settings to make it more accurate.

Are the wrist mounted ones more accurate or do they (as I suspect) use the same tech as the Edge?

Where was it whilst you were running? IIRC Garmin advise the display should be pointing skywards. I have noticed on my 200 that it seems less accurate when it slips round the bars and display is no longer facing the sky.

I went for a ride comparing my phone vs Garmin. The phone recorded quicker segment times and the Garmin. There is also a local Bermuda triangle where the GPS drifts whether I’m running or riding.

I have an Edge 500, and use a wrist strap for running.

Also when I upload into Strava and Garmin direct, the Strava distance seems to be longer (was half a mile difference) when I went for a long run recently.

Where was it whilst you were running?

It was in my pocket, suppose that won’t have helped.

Do you have the latest firmware? My Edge 500 insistently read 10% under a mate’s device. Checking with the car odometer, it was the same amount out with that.

I updated the firmware to the latest version, and it’s now bob-on.

I was checking the accuracy of my Edge 800 on my road bike yesterday. I had a Cateye Strada triggered off the front wheel and the Edge 800 triggered off the back wheel speed sensor and set to manual calibration. I set the wheel circumference’s the same (2093mm) and at the end of the ride (63.7 miles) the rear wheel had recorded 1% more miles than the front. My next step is to set the Edge to Auto calibrate and check the accuracy then, after that I’ll try the GPS without the speed sensor, but I doubt it will be as accurate due to the varying GPS signal due to tree cover etc.

Are the wrist mounted ones more accurate or do they (as I suspect) use the same tech as the Edge?

Usually more so, as they get a better view of the sky than an edge which is either in your pocket or under your torso on the bars.

Garmins usually give a more accurate (and longer) distance than phones as the sampling rate is higher so they actually log you going round corners, rather than just two points either side and a straight line between them. And they’re usualy somewhere with better reception than a pocket.

I have an “orange” 310XT Garmin which always seems to record 1% low compared to whatever local road race I’m doing.

But if you look at the guru’s review of the Edge 200, you’ll see the update rate is set to “smart”. I suspect that this Garmin trick to reduce the update rate is the cause of you errors.