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fishboy

Getting aero and pacing for TristanP

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I found this at home in the medical kits yesterday...

 

Aerowash.jpg

 

Not wanting to give away too many free trade secrets you know, but this is what I will be using to clean my bike from now on... Its got the marketing possibilities of Power Balance all over it!

 

It says Aerowash BTW

Edited by TristanP

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Is that a euphemism?

It wasn't intended to be.

 

But just thinking about it, perhaps it could be if Ratdog decided to go on one of those weird Euro protest nudey rides..................

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And Stikman isn't one? :lol:

 

Sorry to disappoint you RD, but that section you had at Busso was probably a. slight downhill, b. tailwinded or c. not quite draft legal (OK maybe not c. :lol:) CdA shouldn't vary from .228 up to .280 or thereabouts over an IM course if you spent most of the time riding down on the aerobars, I'd expect may be 0.015-0.020 difference.

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RD, I reckon this is more typical of your position.

I looked up the BOM website for Busselton on Dec 4, 2010 and got at 9am 19C, 58% humidity, 1007 hPa.

I reckon 0.005 is a better estimate for a smooth open road, 0.004 comes out at carnegie velodrome and that is quite a smooth surface.

 

This has a ride time of bang on 5:00:00, (or within a few sec of your actual ride time).

 

If you spent a bit of time sitting up out of aero then your base position is a bit lower than this drag, but not much.

 

You submitted the following information:

Mass: 90 kg

Air density: 1.196

Speed: 10.03 m/s

Slope: 0

CdA: 0.283

Crr: 0.005

Power: 215 watts

 

If your drag was that low, I'd expect you to ride a whole lot faster off those watts, somewhere between 4:30 and 4:44...

 

Mass: 90 kg

Air density: 1.196

Speed: 10.73 m/s

Slope: 0

CdA: 0.228

Crr: 0.005

Power: 215 watts

 

38 23.6 10.56 207 04:44:12

40 24.9 11.11 236 04:30:00

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sweet

 

Today I did a 2km standing start TT effort just for shits and giggles. There was a huge head/side wind and I was on my training bike which has the same fit but crappy training wheels. Obviously not the best way to check CdA but thought id show it here for comparison sake.

 

2 km in 2:46 or 43.4 km/hr with an normalised power of 377watts. Wind has a huge influence and as we all know its hard to judge when its coming from behind, but always can feel when its coming from the front.

 

You submitted the following information:

Mass: 90 kg

Air density: 1.199

Speed: 12.06 m/s

Slope: 0

CdA: 0.318

Crr: 0.004

Power: 377 watts

TTbike2km18-4-2011power.jpg

 

 

I cant wait to analyse the figures after port mac and then work from there on position for Cairns.

 

Have you got a wind tunnel booked soon?

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2 km in 2:46 or 43.4 km/hr with an normalised power of 377watts. Wind has a huge influence and as we all know its hard to judge when its coming from behind, but always can feel when its coming from the front.

Use the section of ride you were not standing/accelerating but a more steady state effort.

 

Normalised Power for 2-min is meaningless, I'm surprised software even allows it to be calculated. Use average power.

 

Wind screws the estimate.

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Today I did a 2km standing start TT effort just for shits and giggles.....with a normalised power of 377watts.

 

Classic! When you took off on that M7 100k TT a year ago, you gave me the "HOLY SHIT"s, and definitely no giggles. I can only imagine what a ratdog 2k TT launch is like!

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Nice thread Fisho

CdA's are a closely guarded sekrit...

 

0.275-0.285 typical triathlete

0.255-0.275 getting better

0.235-0.255 getting good, but you'll need a lot of tweaking to get here if you have shoulders, or are big

0.215-0.235 super good, but unlikely you'll get in this range without a skinsuit and pretzel like abilities, probably impractical for ironman or halfs.

< 0.215 slippery like a fish

< 0.200 aero god/goddess

0.195 Dave Zabriskie, winning world TT champ

0.185 Levi Leipheimer, lowest recorded CdA of TT cyclist at LSWT in San Diego.

Just chucked in a couple of numbers from a few races and it spat out results from 0.224 to 0.245 which seems ridiculously low for me ~78kgs, 172cm, with pretty flat back, crono 05, hed jet 60 front, wheel cover on the back, BUT very wide elbow position due to previous shoulder injury (outside of elbows around or just inside outside of hips so maybe ok??)

 

Going to do some serious testing now Ive got no roadie for a few weeks :lol:

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My figures are coming to be insanely unaero - in the range of .34 +

 

Someone needs to help me

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Post piccy's front and side and I'll run my eyeball wind tunnel apparatus over your setups to sanity check your results (last time testing for Tristan last week my eyeball estimate was only 0.005 off).

 

Also note that checking sections of open road where you may get interference from cars or other competitors can skew your CdA.

 

Even at 12m separation, you get a drag reduction from sitting or riding behind someone in low yaw conditions.

 

If you want to be accurate you do need to find some quiet, flat road or a velodrome on a low wind day.

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I will do it tonite. I think you will laugh and rubbish me and tell me to try my hand in kite surfing.

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Even at 12m separation, you get a drag reduction from sitting or riding behind someone in low yaw conditions.

 

If you want to be accurate you do need to find some quiet, flat road or a velodrome on a low wind day.

I think thats my problem there. Being a crap swimmer means I get to overtake lots of people on the bike (most of who then overtake me on the run, but thats for another thread :lol: ) so my CdA would appear to be lower than it actually is.

And all the data I chucked into you calculator was from races

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