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Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data?
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I think my PM is reading low (yeah yeah, I know).

But, when I put my data in from a recent event I would have to have a CRR of under .003 and a CdA of under .180 to come up with something remotely close to the power recorded for the ride.

I know for fact my combined CRR on those roads isn't under .003. So I used that. I put in the actual Weather Underground data to get the air density, put in accurate road grade average, etc.....

To arrive at a CdA of closer to what I'd expect, I'm having to put in 40w more into the calculator than I did. Which, coincidentally, is about how much lower this meter reads on the outdoor TT bike versus an indoor hub based Powertap stationary trainer setup to my exact fit coordinates.

Outdoors with my position and equipment, I ain't nowhere close to a .180 CdA. No freaking way.

Is the aeroweenie calculator acceptable enough to know my Stages I'm using was reading pretty damn low for the event?

I typed my data into my personal Excel calculator based on some of the Chung formulas and the CdA also had to be super low to make the power figure make sense.

I use this meter on my road bike also, shorter cranks there also (crits). Can't really tell due to high power surges in training rides and variable terrain.
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [burnthesheep] [ In reply to ]
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do you have a big hill you can test on ? My 2km 8% hill is great for detecting bad PM calibration :-)
Last edited by: marcag: Feb 15, 20 9:13
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [marcag] [ In reply to ]
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I've got a short hill out of the house that's 8% and super steady. It's only about 90 seconds to get up it. But that's probably long enough. I'd have to suck it up and stay in aero up it, but would work.

I'll try it. Worth a shot.

I don't think it's one of those "everybody thinks their meter reads low" kind of things if I have to put in super unrealistic numbers to make the power figure make sense.

Or, I could borrow a local's meter. Not sure anyone on the team has one that's a 165 length though. I still have my old 175. I guess I could use a speed sensor on a trainer. Run the same speed and see if there is a difference. I would assume that would show if there's a gasping difference like 30 to 40w.
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [burnthesheep] [ In reply to ]
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Jack's calculator agrees with my calculations.

If you're sure about the inputs then a 40 watt discrepancy is ... disquieting.

I'd try the 8% hill. You don't really need to stay aero all the way up -- you'll probably be going slow enough that aero isn't going make that much difference.

If you happen to *absolutely know* how high the hill is, you'd be in even better luck. This guy is a road engineer who designed the road he was using for testing.
Last edited by: RChung: Feb 15, 20 9:32
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [RChung] [ In reply to ]
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Sooooo, I am just a moron. Perhaps.

I put them on the trainer.

The one reading low read 25 to 35w lower at 20mph on the trainer. Hmmm.

Ok. Reverse the effect by putting it back on. This time, let’s go easier on the screws on the crank. Better.

I had the crank screws way too tight it seems.
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [burnthesheep] [ In reply to ]
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This is a good outcome. You learned something that was easily correctable because you had another way to check the power. Not everyone does.
Last edited by: RChung: Feb 15, 20 12:17
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [RChung] [ In reply to ]
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Fwiw the zero cal values were also outside the Stages recommendations of 890 +\-50. Was only 838 or so.
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [burnthesheep] [ In reply to ]
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Curious what crank also? I've never had good luck when my old team used stages. No matter what there were discrepancies.

The only thing I truly trust every day is my SRM data. I've used them when team sponsored or not. I'm using an SRM Origin now.
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Re: Is the aeroweenie calculator "acceptable" for a "stink test" of my PM data? [turdburgler] [ In reply to ]
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167.5 Gen 2 Stages Dura Ace.


Long run I’ll likely go with something else on the TT bike more accurate.

For now, it is what it is.

Just nice to post ride data dump to see how aero I stay and how the setup is doing. I do my TTs by feel mostly anyway and my HR data usually shows I nail the efforts and splits (even if I’m still not very fast). A steady ramp to failure just across the line.

It was the data from the wrong way DQ race (topic is on here) where I was smoking fast. I wanted good data for that so badly.
Last edited by: burnthesheep: Feb 15, 20 16:06
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