Verifying power meter

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dusty_nz

Likes Dirt
Just looking for some advice. Have a stages crank and have a suspicion that it is reading high.

Are there any tips for verifying accuracy of the meter.

Calibration and calibration number are all in spec and readings are consistent.
Garmin 1000, 500 and Bluetooth (phone) seen to give the same numbers
 
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Cúl-Báire

Likes Bikes and Dirt
Do you have another PM or past results to compare against?... Perhaps wattage output changes that aren't attributable to performance improvement?

I.e. Golden Cheetah, WKO+ et al offer some kind of means to track efforts month to month, which might produce an outlying result.

aner.jpg

Alternatively, maybe you are just getting faster :dance:



** Also worth noting if it's the only PM you are using, and it's consistantly reading high, it shouldn't matter as your zones will be set relative to the figures it produces. You could also be left leg dominant!.. There is a monster thread on Stages PM's over on BNA which might be worth a read.
 
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dusty_nz

Likes Dirt
The numbers are very high. It logged me holding 1000 watts for over 30 second's and I was still in the saddle. Only had it a month.
 
Pastavore

Pastavore

Eats Squid
dusty_nz said:
The numbers are very high. It logged me holding 1000 watts for over 30 second's and I was still in the saddle. Only had it a month.
Click to expand...
Are they consistently very high, or was that 30 seconds an aberration? If they are consistently reading like that, then yes, send it back*






*unless yes you are 200kg of solid muscle.
 
RB 24

RB 24

Likes Dirt
Yeah send it back. I have tried a stages and I reckon it was around 15% variance in the positive compared to the quarq. I thought I had a big day and found an increase of 200 wts for a 15 second threshold.. enough time to take a snap on the phone an use for bragging rights. I think it worked out I had a p/w of 5 watts per kilo or something like that.. Everyone now calls me 'Fluro... 18 watts of pure power'.

Tipping it just needs a recal. The whole one foot thing isn't that big a difference than 2 strain gauges..
 
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dusty_nz

Likes Dirt
Could somebody do a few runs that meet three following criteria.
Constant speed of 30kph.
Flat terrain.
1000m long
No to minimal wind.
On a road bike.

That should provide a standard amount of resistance and power. Would be good to do calibration removing most outside factors. Only thing left is body weight which is insignificant on the flat at a constant speed.

Also state body position. Drops, hoods, tri bars?

Maybe even a stava link to the run?
 
C

Cúl-Báire

Likes Bikes and Dirt
Ahhhh a lot of variables... But somewhere around 150-170w is what I would expect to see on screen doing 30 clicks, on the flat on the drops/hoods! I am "big boned" though :heh:

Where you located dusty, it might be easier to borrow a pm and test using that. Alternatively send it back and say WTF is this shit!
 
C

Cúl-Báire

Likes Bikes and Dirt
I guess as long as it's constant it's irrelevant if it reads over or under "actual" power (if you are only using that PM). Your efforts will always be gauged off the FTP you set using that Powermeter. Eventually you will know roughly the sort of wattage you are putting down on just feel! :playball:
 
pistonbroke

pistonbroke

Eats Squid
Do you use Strava? Set up Strava on your phone that isn't linked to the pm. Go and ride a few local segments. It will give you estimated average power figures for those segments. Not perfect I know, but may show up any major issues.
 
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dusty_nz

Likes Dirt
Strava Runs

The Strava run was not a bad idea.

I do run strava and keep the weights pretty accurate. Bike as well as me.

Ran Strava on the phone and garmin captured power meter etc. Two separate runs in Strava for the same ride.

Strava Ride : 258 est
Garmin : 263 weighted ave power
Not bad

1.1km segment with roll 9m climb.
Strava : 253 est
Garmin : 233w

Longest non stop segment was 6.3km.
Strava: 267
Garmin 250

Maybe Its not as bad as I thought.
 
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