Whats more accurate, a Garmin or iphone?

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  • Whats more accurate, a Garmin or iphone?
  • tagnut69
    Member

    A little while ago I was on a ride with a mate, we did 20 miles on road but on checking the data of our rides on strava there were significant differences in the figures. We are both the same age, height and weight, rode side by side on the same course, our mileage was only a few yards out but calories was near on 400 different and wattage around 100 different. I was using my Garmin edge 25 uploading to strava via Garmin connect, mate used his iPhone and direct in to strava, neither of us had any other sensors like heart rate, cadence or power.

    So which would be the more accurate?

    hols2
    Member

    My guess is that you would find they are both too inaccurate to be of much use for training. If you’re using it to impress ladies down the pub, just use whatever number is better. If that’s not good enough, just make one up.

    Premier Icon Yak
    Subscriber

    I think all the calorie/power data for both is entirely made up. If you had a big pub lunch then go for the bigger figure 😉

    For the rest, probably the iPhone. My garmin 200 undermeasures compared to my mates iPhone and other more expensive garmins. The 25 is just the newer 200 isn’t it?

    Premier Icon slowoldman
    Subscriber

    If there is no heart rate or power input I doubt either are accurate.

    Premier Icon Mad Pierre
    Subscriber

    Neither without the extra sensors!

    I’m surprised the mileage wasn’t different by a bigger margin too! Phones use assisted GPS (usually less accurate overall) and Garmin doesn’t.

    A shed load of settings for both can also affect all things!

    Premier Icon cookeaa
    Subscriber

    So which would be the more accurate?

    Neither is more “accurate” they’re just gps tracks, the Calories and Wattages are estimates based on that plus whatever other data/information you’ve provided to Strava.

    For example it takes account of the type of bike you tell it you are using, try editing your ride and telling it you used an MTB and then change it to a Road bike, I bet the estimated figures change significantly…

    The fact that you basically did the same route at the same time matters not a jot to strava’s al-gore-rhythm, if you’ve told it you weigh 20kg more and you’re using a Fat bike, it will estimate your Calorie use / power output as being higher than your svelte buddy on a Road bike…

    Crap in, Crap out is the old adage I believe.

    100mph
    Member

    Riding with my mate who uses an iphone and I have an 820 + HRM, his calories burned figure is usually double mine on every ride.

    ads678
    Member

    I use a Garmin Fenix 5 to record exercise, which syncs with Garmin connect app then transfers to Strava. Strava data is always different to garmin data, strava always makes me faster, and gives me a bit it of extra length!!

    Premier Icon cookeaa
    Subscriber

    Actually OP it is worth getting a HR Strap to use with your Edge 25, it’s about the most useful £30 you can spend on and item of “Sports science” kit (IMO). Both because it gives a more accurate picture of the work you’re body has done over the course of a ride, and allows you to gauge your current workload and adjust as appropriate during a ride.

    Premier Icon oldtennisshoes
    Subscriber

    strava always makes me faster, and gives me a bit it of extra length!!

    *signs up for strava*

    Garmin has always calculated things differently to Strava – for example I’m pretty sure that GarminConnect ‘trusts’ your device’s elevation data whereas Strava cross-references your GPX position with (OS?) maps to calculate elevation. I presume that’s why I can see different cumulative height on GarminConnect vs the same upload when copied into Strava. That doesn’t explain why two similar rides on Strava can have such wildly different calorie data, though. Are your weights (according to Strava profile) similar? Do the elevation profiles of the rides appear similar?

    Riding with my mate who uses an iphone and I have an 820 + HRM, his calories burned figure is usually double mine on every ride.

    Is that off-road? If so, that’s my experience too. I guess the algorithms that calculate energy expenditure based on height gained don’t take into account how smooth or techy trails are. We all can appreciate that riding 100m of vertical on a road vs riding on a rocky singletrack parallel to the road.

    I always get a higher calorie count when I’m using HRM but on the road the difference is not that much. Off road the difference can indeed be twofold IME.

    Premier Icon ta11pau1
    Subscriber

    Even with a HRM I take the strava calories burned figure with a pinch if salt.

    Apparently on a (albeit fairly tough) 33 mile, 3hr muddy gravel ride the other week I burned 3,860 calories.

    Premier Icon jam bo
    Subscriber

    neither are accurate.

    bike type makes a massive difference on strava. my default bike is my mtb, it overestimates a road ride power/calories by ~50% if I leave it set to that.

    Premier Icon Paceman
    Subscriber

    Using the Strava app via iphone/android smart phones invariably gives faster, longer and higher climbing results than Garmin devices based on comparisons between riders on our group rides. Most of us have stopped caring now though.

    Premier Icon ampthill
    Subscriber

    Phones generally have good gps accuracy as they are big enough for a big reciever. Little Garmin watches aren’t great

    The only real figure I’ve ever seen are here

    https://fellrnr.com/wiki/GPS_Accuracy

    antigee
    Member

    if the pilot is incapacitated in a light plane then Garmin can land it….

    believe siri can tell you what plane is about to crash land into your house

    @ampthill useful read thanks

    Premier Icon Twodogs
    Subscriber

    If you haven’t got a heart rate monitor or power meter, calories and power are basically a made up number

    DickBarton
    Member

    Are both set to record every 1 second? The one that does that will be more accurate for distance and route. For other measures like power then without sensors it is a guessing game.

    erictwinge
    Member

    i wouldnt have a frickin clue about wattage or calories or whether the times are off, but i just know if ever my garmin is flat and i use the strava app on my phone instead, the lines on the map are incredibly more precise!

    Premier Icon schmiken
    Subscriber

    The only way to get a semi-accurate calorie burn is with a power meter. But even then, that only tracks how much power you put into the pedals – 30 minutes on a pump track apparently only used 25 calories last time I went!

    Premier Icon ampthill
    Subscriber

    FYI

    If I use my watch to monitor a ride then Strava trusts the height data and gets out wrong. You can ask Strava to correct it but only on the web page. Which is annoying

    So, ironically, it’s less hassle to use my phone as Strava doesn’t it so cheers the elevation

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