Getting power from Garmin Edge 500 on turbo trainer

nick_1978

Hi,

I've got a Garmin edge 500 with cadence sensor and when I use my indoor trainer, I turn the GPS function off, do my session then upload to strava. But Strava never gives my power output for the session.
Even with my weight and bike weight entered in strava, it still doesn't want to know.

What am I doing something wrong?
Does Strava need a GPS fix for the session to measure power? Even though I'm indoors?
Outdoor rides are fine (apart from weedy power outputs!)

It would be quite handy if I could get this feature working on my rollers / trainer...

I'm really struggling to find out any info on this. So thanks in advance guys...

danowat

https://strava.zendesk.com/entries/2042 ... ure-power-

FTR, guessed, assumed, calculated, virtual power is bunk'em, no matter what they say.

bobones

nick_1978 wrote:

Hi,

I've got a Garmin edge 500 with cadence sensor and when I use my indoor trainer, I turn the GPS function off, do my session then upload to strava. But Strava never gives my power output for the session.
Even with my weight and bike weight entered in strava, it still doesn't want to know.

What am I doing something wrong?
Does Strava need a GPS fix for the session to measure power? Even though I'm indoors?
Outdoor rides are fine (apart from weedy power outputs!)

It would be quite handy if I could get this feature working on my rollers / trainer...

I'm really struggling to find out any info on this. So thanks in advance guys...

Noticed the same thing myself and opened a support ticket because I saw calorie and power figures for other Strava users who were using stationary trainers. Strava support guy was pretty useless and I didn't get a satisfactory answer. However, when mucking around I discovered that if you edit the ride and uncheck "trainer", save it, then recheck "trainer", save again, you get the power and calorie information displayed .. for what it's worth!

amaferanga

How can Strava even begin to guess power from a turbo or roller ride without knowing the resistance curve of the turbo/rollers you're using?

huw123

I ride with a Powertap and use Strava and the "estimates" that Strava displays are way out, so I would use the power data with caution anyway, if you don't use a power meter.

For something a bit more accurate on a turbo trainer have a look at:

http://www.trainerroad.com

They've calibrated most turbo trainers to actual power meters and it gives a far better estimate if you've not got a power meter.

bobones

amaferanga wrote:

How can Strava even begin to guess power from a turbo or roller ride without knowing the resistance curve of the turbo/rollers you're using?

I was only looking for calorie burn, not power, but Garmin Connect also attempts to guess calorie consumption. I'm guessing they use duration and HR, possibly speed. If speed is used then it is utter rubbish because they have no way of knowing resistance. Incidentally, 2x20 @ tempo for me this morning was reported as 349cal by Strava and 530 by Garmin. Most likely not worth looking at any of these figures.

nick_1978

bobones wrote:

Noticed the same thing myself and opened a support ticket because I saw calorie and power figures for other Strava users who were using stationary trainers. Strava support guy was pretty useless and I didn't get a satisfactory answer. However, when mucking around I discovered that if you edit the ride and uncheck "trainer", save it, then recheck "trainer", save again, you get the power and calorie information displayed .. for what it's worth!

Well, I've just tried this work-around and it works fine! Thanks for that.
It's a bit annoying to have to do that everytime I have a roller session though, I guess Strava just needs an elevation reference to perform it's power algorithm... or some magic like that.

amaferanga wrote:

How can Strava even begin to guess power from a turbo or roller ride without knowing the resistance curve of the turbo/rollers you're using?

I don't know, ask them. They must use some generic resistance figure for stationary trainers, along with the other variants like body weight and bike weight at a guess.
I wasn't going to hold Strava to the fact my average output power for the hour was 194W, I just want to use that reading as a reference myself, for future indoor sessions on my own rollers.

Thanks for all responses, looks like I wasn't the only one who couldn't figure it out.

richa

amaferanga wrote:

How can Strava even begin to guess power from a turbo or roller ride without knowing the resistance curve of the turbo/rollers you're using?

The only way i can see it could estimate would be by HR using your HR/Power curve on non turbo rides.

But still. What is the point of guessing power. Power has become too normal. Its like an app/website without an esti-meter isn't worth using. Crazy.

Alex_Simmons/RST

bobones wrote:

I was only looking for calorie burn, not power,

if you are measuring one, then provided you are also measuring time, you are automatically measuring the other.

power = energy/time
energy = power x time

As to the accuracy of the methods used to estimate the quantity of energy used/transferred, or the rate it is occurring, that's another matter.

Herbsman

Just forget about power and calories and ride your bike...