Measuring my w/kg

pollys_bott

New work gym boasts a WATT bike - could someone please confirm the basic test I can do to measure my wattage output on said bike. It's average wattage over an hour / body weight in kgs, yes? (As opposed to 10 / 20/ 30 minutes)

Cheers

amaferanga

If its FTP you want then that's average Watts for an hour divided by your weight in kg.

Many people do a 20 minute test though as an hour all out on an indoor bike is a miserable experience. Rule of thumb is your 60min power should be around 92-95% of your 20 minute power I think.

StorckSpeed

See PM

amaferanga

StorckSpeed wrote:

See PM

Why not share your words of wisdom with the world?

StorckSpeed

I have an excel spreadsheet which if you do a 3 minute test, a twelve minute test and a 20 minute test will calculate your Critical Power and then from your weight will also calculate your W/Kg.

sub55

First thing , dont assume that a gym based bike will give you an accurate power output because they dont.
Which means that your figures wont mean diddley squat , that said ,as long as you can re produce a set protocol and the bike is consistant, the figures will tell you if your heading in the right direction or not . Though quantifying bike consistancy might be guess work.

The Bounce

Pollys Bott wrote:

New work gym boasts a WATT bike...

sub55 wrote:

First thing , dont assume that a gym based bike will give you an accurate power output because they dont.
Which means that your figures wont mean diddley squat , that said ,as long as you can re produce a set protocol and the bike is consistant, the figures will tell you if your heading in the right direction or not . Though quantifying bike consistancy might be guess work.

Perhaps you should have read this 1st... http://wattbike.com/uk/wattbike/accuracy_and_calibration

Alex_Simmons/RST

The Bounce wrote:

Perhaps you should have read this 1st... http://wattbike.com/uk/wattbike/accuracy_and_calibration

Or this:

CoachFergie

Damn you and your science!!!

amaferanga

Alex_Simmons/RST wrote:

The Bounce wrote:

Perhaps you should have read this 1st... http://wattbike.com/uk/wattbike/accuracy_and_calibration

Or this:

Errors of <~10 W up to 400W doesn't seem bad. Is that showing the variation in error on a single Wattbike or 5 different ones?

Here's (part) of a paper on the accuracy of the Wattbike compared to a SRM (you can preview much of it).

The Bounce

Alex_Simmons/RST wrote:

Or this:

So, what are you trying to say Alex? That the two statements from the AIS at the top of Wattbike's page... that's your AIS by the way, are not accurate or true?

Alex_Simmons/RST

The Bounce wrote:

So, what are you trying to say Alex? That the two statements from the AIS at the top of Wattbike's page... that's your AIS by the way, are not accurate or true?

That data is from SASI, not AIS.

Interestingly, the statements were changed once Wattbike became a sponsor.

All I am saying is that Wattbike claimed a level of accuracy that was not backed up by formal testing by a sports institute.

RChung

Alex_Simmons/RST wrote:

Interestingly, the statements were changed once Wattbike became a sponsor.

Holy cow.

Alex_Simmons/RST

amaferanga wrote:

Errors of <~10 W up to 400W doesn't seem bad. Is that showing the variation in error on a single Wattbike or 5 different ones?

5 different ones. Out of the box the calibrations were different. ~25W different at 300W is a big chunk of change in my book. The slope isn't great on 2 units, and good on 3.

When you sell accuracy, you should provide it. This is what they claim:



So when I see testing that suggests it might vary by between 5%-10% depending on what unit you happen to get, and it should be less than 2%, I wonder why?

amaferanga wrote:

Here's (part) of a paper on the accuracy of the Wattbike compared to a SRM (you can preview much of it).

Thanks but couldn't see the paper from that link. Says paper is unavailable.

Nothing against Wattbike, it's a great training bike. Has a few quirks like cranks that don't suit some riders and non cycling handle bars. Lack of programmability of resistance is a big let down in my book.

Alex_Simmons/RST

RChung wrote:

Alex_Simmons/RST wrote:

Interestingly, the statements were changed once Wattbike became a sponsor.

Holy cow.

Well I am hoping that the data from 2009 testing performed by SASI was fed back into the Wattbike team and they have since worked out how to provide well calibrated units every time. But I have no idea on that.

I wish I had the original statements somewhere, but at least I did keep an image of the test result summary.