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aero data
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I have been using best bike split to try and figure out my position and gear selections. What things could make the data appear you are more aero than you actually are. I have a stages power meter and guess it could be reading lower than it actually is. I am sure weight also affects the data. Went for a 33 mile ride yesterday with my hed 60's wheels and 4 season tires. Crap road helmet. Ok fitting tri suit but no my race suit. cervelo p5. took right at 1:30 and 20.8 mph. Pushed 218 watts. said my cda was .23. I have a pretty good position but not super aggressive. I feel like i really have found how to tuck my head from watching you tube videos. I know these are all estimations but wondering how close that really is.
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Re: aero data [marath8] [ In reply to ]
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Off the top of my head
power meter calibration
wind
weather change
traffic
crr changes
moving on the bike

BBS is usually not too bad at it's estimates. I have seen a few times that it was wildly off however. For the most part, just figure it's a rough guess and you'll be happy. It would be pretty tough to test a vs. b stuff with BBS though. Have you read the Platypus thread?

The Artist formally known as Leegoocrap
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Re: aero data [marath8] [ In reply to ]
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if using the aero analyzer beta version, toss it out the window. i checked that out for a ride where i held same position and the data points had my cda vary from 0.13 to 0.34
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Re: aero data [Morelock] [ In reply to ]
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Yes I have read most threads on cda. My problem is I live in the middle of nowhere and the wind always blows. No real good spot to do trial runs. thanks
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Re: aero data [marath8] [ In reply to ]
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Is there a straight section of road say 1km that’s in line with the wind so you just get a head/tailwind?

Stages pretty much a non starter for aero testing in most people’s experience.

Making aero easier at Red is Faster
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Re: aero data [SkippyKitten] [ In reply to ]
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i was afraid of that with the stages power meter. I was in a bind and it was the best i could get. the number seemed low for my gear so I would just have to guess its probably not going to be very accurate. I have a race in boulder in july that i will use best bike split for estimation and see how accurate it is. Just hoping to get something else for day to day stuff. All my biking is done on a major highway with a good shoulder. Other roads with no shoulder and people will run you over unless you ride in the middle of the lane and then then get pissed.
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Re: aero data [marath8] [ In reply to ]
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What’s ur weight. That seems slow for those watts. Bigger upper body, more resistance. I am 140 and can do that on 165w on my Trek SC road helmet and road kit with reg wheels and Gators.

Either position, PM, or weather(wind). My .02
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Re: aero data [Sbernardi] [ In reply to ]
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6 ft 155 lbs. thats what makes me wonder about the cda. .23 seems pretty aero but speed not so much
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Re: aero data [marath8] [ In reply to ]
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Are ur brakes rubbing? Lol yea that’s gotta b off
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Re: aero data [marath8] [ In reply to ]
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With a .230 CdA, you'd need ~105 watts to overcome aero drag at 20.8 mph. With another 3% lost to drivetrain inefficiency, that would mean you have 115 watts of rolling resistance. Either you have the WORST. TIRES. EVAR. Or the .230 CdA is way below reality. Or the power meter is reading way high. I'm gonna guess one of the latter two.
Last edited by: gary p: May 17, 18 13:43
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