thechemist

https://www.cyclingpowerlab.com/power...libration.aspx

All of this also brings up a good point in that some may think it is a MAJOR hassle to check calibration/slope. As TR pointed out, it really isen't hard to do. All you need is an ACCURATE weight(20kg is what I will be using with quarq) and like 5 minutes. You can also measure your weight at USPS to see if you can get +-2%.




edit: sorry to hear gsteinb

rbart4506

Yea I was curious about that too?

With the new Riken I'm seeing higher numbers then my S975 and that's indoors. I have made adjustments to my FTP moving forward and of course zones for training. It's not very often I look back at what I did power wise and use TT times, general race results and performance in team rides a s measure of progress.

With all that stated, I am never at the pointy end of the race so I feel I can take a less then critical view of these numbers. That, and I have more important things to occupy me mind.

Now if it's a relatively simple process to check accuracy and make adjustments then I'd be into that for sure.

mike868y

i don't know about you guys, but i wouldn't trust the accuracy of the scale at my local usps.

thechemist

It would just be to verify your known weight. So if you have 50lbs and USPS weighs it at 50.05 you are good to go.If I recall though, USPS scales have to be pretty accurate per policy. Obviously the better option would be to get a calibrated test weight.

globecanvas

My formal training is in statistics, finance, and engineering. There's a philosophical hurdle that people who work with statistics in the real world have to cross, which is understanding that any measurement and prediction system will have inputs that are inaccurate to some degree, that the resulting inaccuracy of the outputs can be estimated, that the outputs are better than just making stuff up even if the inputs are inaccurate.

Every input has error bars around it: the power meter, what you think your zones are, how your body will adapt to specific work in any given zone, and so on. You want all of the estimates to be as accurate as possible, because that contributes to the effectiveness of the whole system. But in the end they are all estimates.

When you see 300W on a perfectly calibrated PM, most of the time that means you're within 5W of that number, but a meaningful part of the time you are further away. That doesn't mean you shouldn't care if your PM is miscalibrated by 10W, but it does mean that at some point, as gsteinb said...

thechemist

the estimated inaccuracy is certainly quantifiable to a certain degree dependent upon your least accurate variable... but you can make all of your variables less than 2%.

globecanvas

Hey, maybe I can derail the holy war with a joke.

A firefighter, an engineer, and a mathematician are in adjoining hotel rooms. Through an amazing coincidence, a small fire breaks out in the wastebasket of each room.

The firefighter sees the fire, rushes into the hall, gets the fire hose, and puts out the fire.

The engineer sees the fire, notices a water glass in the room, does a quick calculation, fills a glass with water from the sink and puts out the fire.

The mathematician sees the fire, notices a water glass in the room, says "trivial!" and goes back to bed.

echappist

That's rather unfounded when you don't have proof. The USPS scale gets calibrated every month, and the scales at FedEx and UPS gets an annual check.

all three told me that the weight plates i had were 19.8 lbs.

gsteinb

I weighed my stuff at home, at fedex and at the USPS.

home - 48
usps - 47, 15oz
FedEx - 48

beatlebee 

Thanks much.

Racer Ex 

I think I could make a compelling case for:

False

True

Racer Ex 

Who needs proof when you have a perfectly good ignorance to fall back on?

Racer Ex 

My response:

MDcatV

stfu MDcatV, if you'd spend less time fooling around on bf and more time calibrating your powermeters, maybe you'd win a race more than once every 6 years.

rbart4506

And there are times when ignorance is bliss

Ygduf

Guys, if all else fails just calibrate your power to your weight on known Strava hillclimb segments.

jsutkeepspining

^meh https://alex-cycle.blogspot.com/2013/07/windbags.html

Ygduf

you know I only mention strava for the outbursts of haters. don't bite and take it too literally.

ovoleg

Strava!!!

rkwaki

Watch the profanity...

ovoleg

ahhahahaha. I sometimes yell "strava" on group rides when I see someone attack the group for no reason. I usually start chuckling so hard its hard to contain myself.

When I first got it, I was going around Strava 'huntin'. Now I just do rides and watch progress.

revchuck 

mattm

I almost fell for it..

Racer Ex 

I calibrated 3 SRM's this afternoon.

Ygduf

don't feel bad. sometimes you're the tortoise, sometimes you're the wombat.