Garmin or Strava?

enzo berzot

On recent rides with my friend my Strava stats are way off his Garmin stats which he uploads to Strava.
Distances are identical, as are calories used but height climbed and average speed are very different despite us cycling together.
Should I bin my free Strava on my phone and upgrade to Garmin kit?

imposter2.0

enzo berzot wrote:

On recent rides with my friend my Strava stats are way off his Garmin stats which he uploads to Strava.
Distances are identical, as are calories used but height climbed and average speed are very different despite us cycling together.
Should I bin my free Strava on my phone and upgrade to Garmin kit?

So what if it's different?

sungod

without a powermeter the calories figure is simply nonsense (even with a pm it's still based on assumptions about metabolic efficiency that may not be correct for any given person)

when computing average speed, i'd assume one is only including time when moving, that can cause a large variation if the other is simply doing speed = distance / (end time - start time)

altitude is always iffy - consumer gps altitude accuracy is poor, barometric sensors are slow to respond, strava has no special magic giving it accurate altitude data for each point on the road

and as m'learned colleague says above, so what? it really doesn't matter, switching to a garmin simply gives you a different set of data, which'll probably still be wrong

enzo berzot

True - they may well both be wrong, but I'd like to base my training on the most accurate (ie. correct) method.
As a disillusioned Strava user I wondered if Garmin was more consistent and accurate?

imposter2.0

enzo berzot wrote:

True - they may well both be wrong, but I'd like to base my training on the most accurate (ie. correct) method.
As a disillusioned Strava user I wondered if Garmin was more consistent and accurate?

The only discrepancies you mention were height gain and average speed. Those are hardly 'critical' in terms of training metrics.

tangled_metal

Does it matter? If you base your training on the same source of data then it's the changes that matter more than the absolute, guaranteed accurate metric. I could be wrong here but I'd worry less about the accuracy and concentrate on relative changes.

bobmcstuff

As a famous statistician once said, "all models are wrong, but some are useful".

The question is, does changing from one wrong model to another give you any additional utility? Probably not in this case.

Personally I like the barometric altitude from my garmin since it's more granular than the map-based calc from Strava, but it still has major flaws (such as if the ambient pressure is changing the altitude gain/lost can be ludicrous).

slowbike

1) Ignore calories burned data - from any source - it will not be right and I think a lot of people just use it to justify the big slab of cake mid ride - if you're trying to lose weight - don't eat cake ... if not, then it doesn't matter.

2) Average speed - moving or elapsed? - If you're trying to get faster over distance then a shorter elapsed time is the ultimate goal - however, most of us use moving speed as that's the one we have most control over.

3) Elevation gain - this differs on the same ride between units of the same make/model - Strava offers an elevation correction that resets it back to it's own calculation based on stored elevation data rather than barometric or consumer GPS derived data - both methods have their limitations - perhaps we should stop looking at absolute height gained (do you count the 6" over each speed bump - do a dozen of those and it's another 6' height gain!) and fuzzy the metric - flat, moderate, hilly or mountainous ... that'll do ..

wongataa

enzo berzot wrote:

On recent rides with my friend my Strava stats are way off his Garmin stats which he uploads to Strava.
Distances are identical, as are calories used but height climbed and average speed are very different despite us cycling together.

Strava average speed is your average moving speed. Garmin average speed is your average speed including stops so it will be lower (on Connect you can see your average moving speed as well. It is usually slightly different from Strava's due to what speed value is used as a cut off - it is higher than 0 to remove GPS drift errors.)

If the elevation is recorded by a device with a barometer and Strava and Garmin are set to use the recorded data the elevation climbed will be identical. If elevation correction is turned on then the recorded elevation is ditched and the elevation is computed from various map data etc. This will produce differences.

davidof

Is your Strava height gained more than on his Garmin?

Strava elevations generally over-read compared to a barometric altimeter.

fenix

Strava on the phone is fine for logging your rides. Don't over obsess on average speeds or anything - routes and weather effect this. Just get out and ride and you'll improve.

enzo berzot

davidof wrote:

Is your Strava height gained more than on his Garmin?

Strava elevations generally over-read compared to a barometric altimeter.

Thanks all for your input.
I'm merely looking for an acurate training mode and appreciate it is unhealthy to be too hung up on stats but it is confusing to see wildly conflicting results.
Here are the stats which are odd - both from 2 riders covering the same route pretty much behind each other with 1 cake stop:
My Strava = 35.7 miles / 1596 feet altitude / 15.8 Ave / moving time 2hrs 15
Pal's Garmin uploaded to Strava = 35.5 miles / 1863 feet altitude / 16.2 Ave / moving time 2hrs 12
Oddly different altitude and average.
I know it is freakishly pedantic but what's the point of basing your training stats on something completely unreliable!

fat daddy

Why do you assume if you move to garmin it's going to be reliable ?? ... it's not, it's consistant to its own algorithms just like strava.

I wonder if your stats had been better than his garmin ones then you would be looking to swap ?

imposter2.0

enzo berzot wrote:

Oddly different altitude and average.
I know it is freakishly pedantic but what's the point of basing your training stats on something completely unreliable!

As I said earlier, basing your 'training stats' on two such utterly irrelevant metrics is a bit pointless anyway. What are you actually 'training' for that requires you to track accurate climbing and average speed?

dabber

enzo berzot wrote:

My Strava = 35.7 miles / 1596 feet altitude / 15.8 Ave / moving time 2hrs 15
Pal's Garmin uploaded to Strava = 35.5 miles / 1863 feet altitude / 16.2 Ave / moving time 2hrs 12
Oddly different altitude and average.

Regarding the different moving time figures, you need to be aware of how Strava calculates what constitutes stoped time... and I quote Strava...

Strava considers a point "not moving" if your speed is less than 0.3 meters/sec (0.67 mph), but we don't start accumulating resting time unless you're "not moving" for at least 15 seconds.

StillGoing

Elevation can be affected by the angle of the device mounting even by a few degrees. There's a YouTube video out there of the same device being tested over the same course at various angles with different height readings as a consequence. Something to do with the barometric pressure.

Mikey23

Speaking personally, I would use your phone for what it does best and get a dedicated gps device, garmin or otherwise for your rides. Otherwise you may find yourself in the back of beyond needing an emergency phone call and find that your phone is out of charge. A 520 with a proper barometric altimeter is relatively cheap and will serve you for years!

davidof

enzo berzot wrote:

e stats which are odd - both from 2 riders covering the same route pretty much behind each other with 1 cake stop:
My Strava = 35.7 miles / 1596 feet altitude / 15.8 Ave / moving time 2hrs 15
Pal's Garmin uploaded to Strava = 35.5 miles / 1863 feet altitude / 16.2 Ave / moving time 2hrs 12

The averages are not bad. For altitude, it is complicated as others have said.

GPS calculated altitudes are inaccurate. Even more so they are inaccurate between each reading. If you are climbing a hill you would expect your altitudes to increase like this:
1,1.5,1.9,2.4,2.7,3,3.5...

but with a GPS you may get

1,1.5,1.3,2.0,2.5,2,4,3,3.5


Altitudes from GPS reported by Strava

where the altitude bounces around a lot, these cause cumulative errors.


Altitudes from Garmin 1000 with barometer - much smoother


If you take the strava altitude data you are relying on the strava data actually being accurate for a given point and your gps accurately reporting where you are. Lots of factors will affect this - terrain, trees, buildings etc. If you are climbing a road that traverses up a hill then a location a few meters to the left or right will make a big difference in altitude and again, all errors are cumulative.

A barometric altimeter is better but are affected by changes in barometric pressure (changing weather) and temperature and tend to under read over long climbs. As reported above some Garmin's are sensitive to wind. (see: https://forums.garmin.com/archive/index ... 33043.html)

Some altimeters will mix GPS and barometric data and you can even enter known waypoints to correct if you pass throught them (useful for summits and cols).

Just a note on the Strava data, they've built up their own database based on barometric data submitted by riders, which is a clever thing to have done but still relies on positions being accurate or dropping obviously erroneous locations from input data.

see also: https://support.strava.com/hc/en-us/com ... elev-gain-

enzo berzot

fat daddy wrote:

Why do you assume if you move to garmin it's going to be reliable ?? ... it's not, it's consistant to its own algorithms just like strava.

I wonder if your stats had been better than his garmin ones then you would be looking to swap ?

True!

meursault

The work guys I regularly ride with, and I, all have Garmins and Strava. The data is always different. It's just a tolerance thing, for data.

enzo berzot

Thanks to everyone for their replies.
It seems there is no definitive answer to my question but really interesting to hear of the pros and cons of both methods.
Looks as though I'll stick with Strava on the phone for now...

imposter2.0

You still haven't explained why elevation and average speed are such essential training metrics for you?

enzo berzot

Imposter wrote:

You still haven't explained why elevation and average speed are such essential training metrics for you?

Yes - my average speed on familiar routes tells me (generally) if my overall fitness is improving over time. Elevation is more out of interest to be honest.
Plus, I like stats..

StillGoing

wongataa wrote:

Strava average speed is your average moving speed. Garmin average speed is your average speed including stops so it will be lower (on Connect you can see your average moving speed as well. It is usually slightly different from Strava's due to what speed value is used as a cut off - it is higher than 0 to remove GPS drift errors.)[/quote]

Only if you've not set it correctly. A Garmin or any other dedicated device, when set correctly, will show both average moving speed and average speed. It's easy enough to differentiate between the two.

mugensi

enzo berzot wrote:

On recent rides with my friend my Strava stats are way off his Garmin stats which he uploads to Strava.
Distances are identical, as are calories used but height climbed and average speed are very different despite us cycling together.
Should I bin my free Strava on my phone and upgrade to Garmin kit?

How do you know that his Garmin isn't incorrect and your phone strava app correct???

Also on the Garmin you can set your home altitude and this may have an effect on altitude gained especially if you are starting from somewhere other than the home location.

wongataa

philthy3 wrote:

wongataa wrote:

Strava average speed is your average moving speed. Garmin average speed is your average speed including stops so it will be lower (on Connect you can see your average moving speed as well. It is usually slightly different from Strava's due to what speed value is used as a cut off - it is higher than 0 to remove GPS drift errors.)

Only if you've not set it correctly. A Garmin or any other dedicated device, when set correctly, will show both average moving speed and average speed. It's easy enough to differentiate between the two.

My Garmin Edge 800 does not have a average moving speed data field. If you want to have the average speed data field show average moving speed you have to turn on auto pause and have it trigger at an appropriate speed. If you don't want auto pause on (I don't) then you have no way of seeing your average moving speed on the device.

My Garmin GPSMap handheld GPS device does have an average moving speed data field as well as an average speed data field.

imafatman

I just got a Garmin 820 having used Strava on my phone for years and have been comparing the two.

Both are reporting very similar distances and average speeds, typically within 3-5%. The most obvious difference is the altitude gained reading. Garmin almost always reads less than Strava, as much as 30% less on one ride. The closest they have been is 4%.

One thing is for sure, the Garmin has a much more accurate GPS. Strava on my phone often ends up looking a bit zig-zagged. Strava must have some pretty clever ways of cleaning up that data.

From what I understand, these miniature barometric sensors are more accurate than GPS but not by a huge margin.... They still have a reasonable amount of error in them and things like temperature and humidity easily affect them.

I love the Garmin on the bike, I'm a bit of a data fiend. The only downside is it's crappy touch screen. It's SERIOUSLY CRAP.

meursault

imafatman wrote:

I just got a Garmin 820 having used Strava on my phone for years and have been comparing the two.

Both are reporting very similar distances and average speeds, typically within 3-5%. The most obvious difference is the altitude gained reading. Garmin almost always reads less than Strava, as much as 30% less on one ride. The closest they have been is 4%.

One thing is for sure, the Garmin has a much more accurate GPS. Strava on my phone often ends up looking a bit zig-zagged. Strava must have some pretty clever ways of cleaning up that data.

From what I understand, these miniature barometric sensors are more accurate than GPS but not by a huge margin.... They still have a reasonable amount of error in them and things like temperature and humidity easily affect them.

I love the Garmin on the bike, I'm a bit of a data fiend. The only downside is it's crappy touch screen. It's SERIOUSLY CRAP.

Tip for the touch screen to try. Touch slightly longer than a 'normal' touch screen, about half a second works for me.