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This is a bit misleading - it depends what you are training for.
Track, TT or flat circuit racing - watts and aerodynamics are the key factors.
Watts/kg is useful for making a profile but it's a bit like BMI in that it can be a bit misleading. Aside from weight, it also only takes 5s, 1min, 5min and ftp power into account so it's not a totally comprehensive review.
dan-
Thank fuck W/kg isn't the be all and end all. :)
There's an aero chart kicking around as well that plots CdA against Watts.
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This is a bit misleading - it depends what you are training for.
True, but W/kg is a reasonable metric to try to improve in the absence of an accurate/cheap/reliable way of measuring CdA. Improving W/kg by increasing W (with no significant increase in kg) shouldn't increase CdA. And improving W/kg by decreasing kg (with no change in W value) should only help reduce CdA. Obviously doesn't help the direct attempts to minimise CdA by changing position/kit.
To adapt/murder the BMI analogy; W and CdA is like BVI (Body Volume Index) vs W/kg =~ BMI (Body Mass Index). BVI (analogous to W and CdA) is a far superior metric than BMI (analogous to W/kg) but very few people have the necessary equipment to accurately measure body volume (analogous to CdA) and so BMI is simpler/easier.
To be fair, I've not played around with the Aerolab stuff in GoldenCheetah (or even have access to anything more professional than that).
It's pretty simple to plot the W/kg values for 5s/1m/5m/ftp for the different "Coggan" bands (untrained/cat-4/cat-3/etc) on a chart and interpolate intermediate values. I was planning on doing something similar combining the style of the Golden Cheetah Critical Power profile page (pure W, no weight taken into account) and the weight (which varies considerably over time for me!). So I'd plot W/kg rather than W and overlay the selected ride and 'best' onto the Coggan W/kg bands. Or I can just go out and ride the bike more.
hippy
Greenbank
That's how I use my PowerTap. I'm in the 'getting fit again' stage and gathering data whilst I do that. I'm a long way off specific training targeting my weaknesses, especially as I have ~15kg to lose. Small increases in the numbers (especially as weight goes down) helps keep me motivated. Most of my data comes from commuting or laps of Richmond Park.
As others have said, don't compare raw Watts, only compare W/kg. The chart in Coggan is good, it's also here: http://cyclingtips.com.au/wp-content/uploads/2009/07/powerprofiling.jpg
I was scraping into mid/high Cat 4 back in 2009 when I was doing lots of Audaxing and I was just starting to make improvements using interval training (5x5 mainly) as I had access to a gym bike at work with consistent power measurement.