Who to believe?

General bike chat that does not fit elsewhere
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wellbeloved747
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Who to believe?

Postby wellbeloved747 » Sat Mar 16, 2013 21:01 pm

Did a 48km ride this afternoon in the crappy weather, i used my new Edge and had Strava running at the same time, they were started and stopped at the same time but the results vary quite a bit!!

Strava on the iPhone 5, in a waterproof case in the centre jersey pocket.

DISTANCE=47.2KM
MOVING TIME=2:02:40
ELEVATION GAIN=376M
CALORIES=1008
MAX ELEVATION=149M


Garmin edge 200, mounted with the included mounting kit, on the handle bars to the right hand side of the stem.

DISTANCE=46.67KM
MOVING TIME=1:48:38
ELEVATION GAIN=262M
CALORIES=1949
MAX ELEVATION=152M

These results are very contrasting, although the Garmin has done less distance and moving time it claims to have done about double the calories?

who should i believe?

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Grill
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Re: Who to believe?

Postby Grill » Sat Mar 16, 2013 21:15 pm

Garmin for everything but the caloric algorithm (which are all rubbish btw).
English Cycles V3 | Scott Plasma 3 TT | BMC TrackMachine TM01 | Ritchey Road Logic | Scott CX Team

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wellbeloved747
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Re: Who to believe?

Postby wellbeloved747 » Sat Mar 16, 2013 21:27 pm

i presume to get a proper reading i need a hr monitor?

Imposter
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Re: Who to believe?

Postby Imposter » Sat Mar 16, 2013 21:36 pm

wellbeloved747 wrote:i presume to get a proper reading i need a hr monitor?


HRM is useless for anything other than HR.

cougie
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Re: Who to believe?

Postby cougie » Sat Mar 16, 2013 22:15 pm

Altitude on these things are bobbins.
Calories are bobbins.
Distance is almost the same.
Time - you probably had auto start stop on the garmin.

The max elevation is almost the same.

Simon Masterson
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Re: Who to believe?

Postby Simon Masterson » Sat Mar 16, 2013 22:25 pm

If the Garmin has an actual sensor on your wheel, then that.

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wellbeloved747
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Re: Who to believe?

Postby wellbeloved747 » Sat Mar 16, 2013 23:32 pm

Nope the Garmin is gps doesn't support wheel cadence, i did have auto stop on but then i thought Strava did? surely because there gps then altitude should be accurate, but i still cant get over the calories because the Garmin is double Strava!

Simon Masterson
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Re: Who to believe?

Postby Simon Masterson » Sat Mar 16, 2013 23:33 pm

Oh dear. :lol:

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Grill
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Re: Who to believe?

Postby Grill » Sun Mar 17, 2013 00:08 am

You have a Venge and a Shiv but didn't think to get the 500? Seems bad...
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Vortice
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Re: Who to believe?

Postby Vortice » Sun Mar 17, 2013 03:09 am

Pretty obvious, but you have Strava and Garmin set up with you correct weight and age?

ChrisAOnABike
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Re: Who to believe?

Postby ChrisAOnABike » Sun Mar 17, 2013 07:05 am

Are your two results both from Strava, having uploaded both, or is one from Garmin Connect?

I did a similar comparison yesterday, using my SGS3 with Strava recording the ride, and the Edge 800 recording, and then uploading the latter to Strava and Garmin Connect as well.

FWIW, my results were fairly consistent:

Edge (Strava) - SGS3 (Strava) - Garmin Connect
Moving Average: 14.9 - 15.0 - 15.1 mph
Distance: 29.1 - 29.2 - 29.1 miles
Calories: 940, 909, 876
Elapsed time: 1:59:12 - 2:00:07 - 1:59:11
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Bigpikle
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Re: Who to believe?

Postby Bigpikle » Sun Mar 17, 2013 08:22 am

The calorie numbers through these devices and software are just guesses - they might as well be blind guesses in all honesty. HR wont help either as you need to know exactly how much work (in kj) you actually did (and to do that you need a power meter) and then you need to know your own unique efficiency eg how many calories do YOU burn per kj of effort expended. Most people get a pretty good estimate of calories burned by simply kj=cals but its still a slight overestimate for many people.

The algorithm used in Polar devices is supposed to be the closest but it is not licensed to anyone else, and Garmins numbers are known to be particularly inaccurate.

Just ignore them and focus on something important...
Your Past is Not Your Potential...

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ShutUpLegs
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Re: Who to believe?

Postby ShutUpLegs » Sun Mar 17, 2013 09:11 am

I'd trust a phone recording device to only get the distance right. Just
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Bozman
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Re: Who to believe?

Postby Bozman » Sun Mar 17, 2013 09:37 am

Just compared my Garmin 500 to Cyclemeter on my iPhone, the difference over 51.5 miles - distance .05 variation, acsent - 7' over 3300' variation and the average speed was 0.02 mph different. The only major difference were calories burnt.

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Pross
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Re: Who to believe?

Postby Pross » Sun Mar 17, 2013 10:17 am

From what I've read on here iPhones aren't great at accurate GPS recording (not sure if it applies with a 5 though). I'd use the device designed specifically for the job but ignore altitude and calories, even with HRM fitted calories is a bit of guesswork - you need power to accurately calculate - and altitude works off barometric pressure.

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De Sisti
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Re: Who to believe?

Postby De Sisti » Sun Mar 17, 2013 10:19 am

With my Suunto T6c I get different hr readings (not by much) and calories expended (big difference)
when I download to Suunto Training Manager 2.3.0 and Suunto Movescount.

(edit; TBH, it doesn't bother me at all, it's just that I thought that the two Suunto interfaces interpret
what they read from the device differently)
.
Last edited by De Sisti on Sun Mar 17, 2013 11:33 am, edited 1 time in total.

Simon Masterson
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Re: Who to believe?

Postby Simon Masterson » Sun Mar 17, 2013 10:22 am

Get a wired computer, and buy some fancy shorts with the change. :lol:

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pride4ever
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Re: Who to believe?

Postby pride4ever » Sun Mar 17, 2013 10:39 am

Strava runs exactly with my computer in terms of distance and thats with it running on Android so....Believe your legs I guess. In terms of calories I dont worry about how many of them I burn on a ride as I'm pretty much see-through as it is lol.
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SmoggySteve
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Re: Who to believe?

Postby SmoggySteve » Sun Mar 17, 2013 11:57 am

Surely the only two things that matter is time and distance. And you could work that out with a stopwatch and a map if you really need to know accurately. If elevation is important, the map can give you that info better anyway. Lot of time goes into making maps in the UK so they are pretty accurate.

Garry H
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Re: Who to believe?

Postby Garry H » Sun Mar 17, 2013 15:20 pm

Pross wrote:From what I've read on here iPhones aren't great at accurate GPS recording (not sure if it applies with a 5 though). I'd use the device designed specifically for the job but ignore altitude and calories, even with HRM fitted calories is a bit of guesswork - you need power to accurately calculate - and altitude works off barometric pressure.

Altitude on the gps unit doesn't work off barometric pressure. It should be reasonably accurate.
Last edited by Garry H on Sun Mar 17, 2013 16:06 pm, edited 1 time in total.


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