Dean V

Same wheel set with a power tap hub.

Abe_Froman

And you're saying that with the exact same wattage, give or take a watt or two, you were producing the exact same speed, within less than say .05 mph? I really don't believe that. What bikes were used? And was it the same rider/kit? Exact same position on the bike?

asgelle

Using a regression analysis or virtual elevation, it isn't necessary to reproduce the same speed or wattage.

Abe_Froman

Yea. As it pertains to a guy on a track with a power meter and 2 bikes...that sounds like a euphemism for "guessing."

asgelle

Really? Blather 'bout Bikes: Aero Field Testing using the "Chung Method" - How sensitive can it be? Since we seem to be referencing Tom's blog here.

Seattle Forrest

That's impressive.

Abe_Froman

Well. There's a spreadsheet, so guess it's got to be right

HTupolev

Dean V didn't claim that it was that close. He said that it was a lot closer to 3W than 20W. .05mph at 20mph would tend to be on the order of 2-ish watts.

Abe_Froman

Well, he's saying he was able to test it. So what was the answer? 1 watt? 3 watts? 11 watts? 20?

asgelle

HTupolev

What Dean V claimed is that it was closer to 3W than 20W, and that he could easily detect anything bigger than 10W. While he may have determined a value, he didn't explicitly claim this; the only thing he's claimed is an upper bound for the difference.

Dean V

Giant Propel 0.15 kph faster than Giant TCR. +/- 0.05 kph.
230w and 36kph.
2 water bottles. Same kit, helmet, position, wheels etc.
The test was hardly the ultimate in accuracy but was good enough to give me a fair indication.

wphamilton

The upper bound would be 11.5 watts then? (if closer to 3 than 20).

I've seen claims of 6 watts, at nebulous speeds, well some higher that I discount to puffery but mostly in that range so I don't have a hard time believing Dean. I think that aero bike should include aero wheels though.

Dean V

45mm deep wheels.

wphamilton

But the same wheels on both bikes. Not saying that you didn't measure a difference between frames, just that aero frame with aero wheels would be an "aero bike" vs non-aero frame with non-aero wheels.

Abe_Froman

Dean V

I could retest with my Madone, but then I am sure you would think of something else

RChung

We went through this last month.

RChung

I think the "Tom Compton Challenge" is more trouble than a "delta mass" test to determine how sensitive the method can be.

What we're really trying to determine is how small of a change in drag we can reliably detect. The Tom Compton Challenge tries to measure the change in aero drag, but a change in any version of drag should also work -- virtual elevation itself is a way to "translate" a difference in aero drag into a difference in elevation. So I've had luck in doing delta mass tests: a test where I compare runs with an empty water bottle and one filled with sand. The empty and full water bottles should have the same aero drag -- the only difference is in the total mass, so you should be able to see a difference in rolling resistance. Rolling resistance scales *exactly* like slope so virtual elevation works really really well for that.

Abe_Froman

Also last month, you never bothered to explain what it was you were doing, or why. Kind of like now.

Abe_Froman

Lol possibly . But it does seem you're actually trying to get real results from it, and not just throwing out random anecdotal thoughts on the internet. I'd be interrsted in what you measure the madone at if you do do it.

RChung

Asgelle pointed at my presentation, which explains what I do, and why. It's really not "efficient" to repeat the entirety here when you can already read it.

asgelle

Definitely a 4 Pinocchio statement. Given you wrote at the time,

Abe_Froman

You really like arguing about things while speaking cryptically, and not offering any real information, do you know that?

Look, I'm not trying to be insulting. But I can promise you that whatever it is you're trying to do with your work, it's being lost on everyone here. You have to explain it. Nobody here, or at least the vast majority, do not have the technical background to decipher the dozens of pages of research article you keep linking and then not commenting on. Most are just too proud to say so

asgelle

Not everyone. Speak for yourself.
Not everyone. Speak for yourself.

But what you write is simply not true. For people who have read the explanation of virtual elevation and taken time to digest it, Robert has been very willing to enter into discussions. Just look at post 119.