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fishboy

Getting aero and pacing for TristanP

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Thanks for sharing the photos Tristan!

 

Some quick Q's;

Elbows much closer together. How does this effect your breathing?

 

Elbows much lower due to forearm angle, side effect is head is much lower. How does this effect your visibility?

 

Seat angle must be close to 90% in the current shot, does this load up your quads or do your glutes still work ok at this angle?

 

Thanks again!

No problem...

 

Any change in position takes a while to adjust to, and I have been adapting to this one for a while now. It is not at a point where I am confident of being not only comfortable for 180k, but more comfortable than my previous position.

 

Visibility? Why do you need to see where you are going??? Its not actually that bad, I watch the road about 3 or 4 meters in front of me, and look up to make sure that there are not issues every now and then. To be honest, if you knew me you would understand that vision is not a high priority. I am almost legally blind without glasses on and I dont race with contacts or glasses, so being able to see much further in front of the bike wouldnt help anyway ;-)

 

I have always ridden a tri bike steep like this. It is something that some people are able to do and others are not. It works for me. It does load up the quads a little more than is you were more slack with the seat angle, but as I said, it works for me.

 

On a side note, if I was racing a 1/2 rather than a full, I would more than likely go a little more Landis on the front. This is faster, but its not comfortable for a long distance. Its something that I tested at Shep half and rode a 2:11 but would not be able to hold the position for as long as needed for a full.

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I ride steep, like really steep... It is an Adamo, and I dont know what the seat angle figure would be with a normal saddle, but it would be well over 80 degrees

The Lilo likes to go steep as well :lol:

 

In fact, having had a recent bike fit check by Parkside, he confirmed to me that I am the current steep seat angle Parkside bike fit title holder.

 

Interested in what your seat angle is when you get a chance to measure it (I'll just need to confer with Parkside to find out exactly where on the seat he measures the seat angle from).

 

TGL

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My IMWA CdA was 0.31. Looks like im ratsh!t,

Thought this might make you feel better Rattie.

 

Did the Kurnell TT this morning. Decided to get as slippery as I could given that it is only 16 km and I don't need to run off the bike.

 

Lowered my bars to the lowest possible level. Moved my aero bar elbow pads as close together as possible. Bought a skinsuit

 

Used my P3 with aero helmet. Only non aero thing I used was my training wheels rather than my race wheels.

 

Power Calculator tells me that my CdA was 0.3367 :lol:

 

TGL

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Are you sure you got all the right settings? Sounds kinda high if you beat TU5, musta been putting out about 650 watts for 16km.

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Are you sure you got all the right settings? Sounds kinda high if you beat TU5, musta been putting out about 650 watts for 16km.

More than happy to be corrected on the settings.

 

I kinda used the default ones except I put in 40kph for av speed (because that was my average speed) and 316W for my av power (which is what my Garmin told me was my av power).

 

Put in 90% humidity (happy to accept that it was 100% given that it was raining). Don't think that I changed any of the other settings re smoothness of road etc. Maybe the road is not super smooth but it is pretty smooth. I guess the only other thing is that there is two turn around points so it is not a point to point course (not sure if this matters but anyway, thought that I would throw this in).

 

Happy to stand corrected re the settings (or anything else for that matter). Very interested in being as slippery as possible and although I didn't have shoe covers or race wheels, I was otherwise in my most super slippery position :lol:

 

TGL

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Sorry Fishboy - forgot to mention that it was also a very windy ride. The course changes compass direction a lot so the yaw angle is constantly changing and wind velocity is also constantly changing as it was quite gusty.

 

TGL

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if it is really windy it throws things off.... that does represent your drag for those horrible conditions, but if it was calm or light winds you'd probably be a lot more aero.

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if it is really windy it throws things off.... that does represent your drag for those horrible conditions, but if it was calm or light winds you'd probably be a lot more aero.

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if it is really windy it throws things off.... that does represent your drag for those horrible conditions, but if it was calm or light winds you'd probably be a lot more aero.

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if it is really windy it throws things off.... that does represent your drag for those horrible conditions, but if it was calm or light winds you'd probably be a lot more aero.

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Were you doing the testing using a motorbike? Seen someone motorpacing a few times between Black Rock and Mordiallic ...

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if it is really windy it throws things off.... that does represent your drag for those horrible conditions, but if it was calm or light winds you'd probably be a lot more aero.

Thanks Fishboy - was hoping that this was the case.

 

Will see how the power calculator goes when I use it to analyse data taken in better conditions. Thanks again for sharing it - much appreciated.

 

TGL

Edited by The Glycogen Lilo

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this is the stuff i put into the calculator

 

You submitted the following information:

Mass: 90 kg

Air density: 1.199

Speed: 10 m/s

Slope: 0

CdA: 0.3131

Crr: 0.004

Power: 223 watts

 

My hands have changed position slightly since these pics. As TGL said maybe its about weight and size.

Lastlap3.jpg

Bike3.jpg

1stlap2.jpg

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I would have thought that my huge aerofoil shaped honker and large overbite would have been somewhat advantageous!

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Were you doing the testing using a motorbike? Seen someone motorpacing a few times between Black Rock and Mordiallic ...

 

Er... no. Motorpacing behind a bike will give you a very low drag number as the motor bike is doing most of the "work" to move air out of your way. Carnegie velodrome is our location of usual testing.

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this is the stuff i put into the calculator

 

 

 

My hands have changed position slightly since these pics. As TGL said maybe its about weight and size.

Lastlap3.jpg

Bike3.jpg

1stlap2.jpg

 

RD, you've got a pretty typical triathlete position... plus big shouders and noggin ... By eyeball I'd say 0.280-0.285 ... if you take a small chunk of data at constant speed/watts (eg. 2 min) in this position and run through the calculator, what comes out? A full IM will have a higher CdA as you spend time climbing, out of the saddle for rests/stretching/drinks etc, whereas holding this aero position is probably the figure above.

 

Some suggestions, bearing in mind: a. I am not a bike fit guru - these are aero purely suggestions, and may hamper your bike fit/function. b. Don't change anything too close to IM, you need time to adapt and c. If you do change things, and it goes wrong, please remember I warned you that this could happen.

 

- Forearm angle: Looks like about 125 deg angle between forearm and upper arm. It may be more comfortable, and more aero, if you tip your forearms up to around 15 deg, reducing this forearm-upper arm angle. It will also help deflect air away from your chest/hip area. Your aerobars might not allow this as you have to rotate the bars up, and keep the base bar flat.

 

- Elbow width: Wide is comfortable. But not aero. If you can, try narrowing the elbow pad width a bit. Again, your bars may make this difficult.

 

- Head: There is a lot of lid up there in the breeze, and the Spuik suits that style with the underside of the lid fitting nicely onto your back. If you can lower your neck and rotate your head up (turtling) you will be more aero, but less comfortable. You may need a different helmet with a shorter tail as a Spuik won't work as well if you do it. This will possibly reduce your frontal area by quite a bit and give you a good drag reduction. It may also be too uncomfortable to ride for a full IM, so use caution. Looking down to relax your neck muscles can help, but you have to be very careful you don't prang into anything... this gets more critical as you get tired!

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Looking at before and after pics and something I have often thought about as I push into the wind, is positioning of the hands at the end of the aero bars.

 

Maybe a dumb question, but if you hold your hands with fingertips together rather than as a kinda fist, is there any difference in aero? Does the 'fairing' created by your hands push air out and around? Or is this just wishful thinking

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RD, you've got a pretty typical triathlete position... plus big shouders and noggin ... By eyeball I'd say 0.280-0.285 ... if you take a small chunk of data at constant speed/watts (eg. 2 min) in this position and run through the calculator, what comes out? A full IM will have a higher CdA as you spend time climbing, out of the saddle for rests/stretching/drinks etc, whereas holding this aero position is probably the figure above.

 

Some suggestions, bearing in mind: a. I am not a bike fit guru - these are aero purely suggestions, and may hamper your bike fit/function. b. Don't change anything too close to IM, you need time to adapt and c. If you do change things, and it goes wrong, please remember I warned you that this could happen.

 

- Forearm angle: Looks like about 125 deg angle between forearm and upper arm. It may be more comfortable, and more aero, if you tip your forearms up to around 15 deg, reducing this forearm-upper arm angle. It will also help deflect air away from your chest/hip area. Your aerobars might not allow this as you have to rotate the bars up, and keep the base bar flat.

 

- Elbow width: Wide is comfortable. But not aero. If you can, try narrowing the elbow pad width a bit. Again, your bars may make this difficult.

 

- Head: There is a lot of lid up there in the breeze, and the Spuik suits that style with the underside of the lid fitting nicely onto your back. If you can lower your neck and rotate your head up (turtling) you will be more aero, but less comfortable. You may need a different helmet with a shorter tail as a Spuik won't work as well if you do it. This will possibly reduce your frontal area by quite a bit and give you a good drag reduction. It may also be too uncomfortable to ride for a full IM, so use caution. Looking down to relax your neck muscles can help, but you have to be very careful you don't prang into anything... this gets more critical as you get tired!

 

 

Thanks Fishy,

 

I have rotated the bars up since those pics and it feels pretty good. Ill see how things go at Port.

 

Softy, I often ride with hands in the prayer position, psychologically it works wonders although im sure The Hot Pants Guru isnt listening to my murmers about the constant head winds.

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Looking at before and after pics and something I have often thought about as I push into the wind, is positioning of the hands at the end of the aero bars.

 

Maybe a dumb question, but if you hold your hands with fingertips together rather than as a kinda fist, is there any difference in aero? Does the 'fairing' created by your hands push air out and around? Or is this just wishful thinking

 

It depends... really small changes in hand position can make a significant difference. Ask Dalai...

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Thanks Fishy,

 

I have rotated the bars up since those pics and it feels pretty good. Ill see how things go at Port.

 

Softy, I often ride with hands in the prayer position, psychologically it works wonders although im sure The Hot Pants Guru isnt listening to my murmers about the constant head winds.

 

Have you got a short run bit of power/speed data (~2min constant speed/watts flat course low wind) to calculate a rough CdA?

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Have you got a short run bit of power/speed data (~2min constant speed/watts flat course low wind) to calculate a rough CdA?

 

This is the best fit (flat i could find from that day in busso

 

You submitted the following information:

Mass: 90 kg

Air density: 1.199

Speed: 10.83 m/s

Slope: 0

CdA: 0.2284

Crr: 0.004

Power: 212.2 watts

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This is the best fit (flat i could find from that day in busso

There you go - you are now in the "super good" category!!

 

Reckon that all you need to do now is get an all over body wax, polish up the helmet and you will move into the "slippery like a fish" category :lol:

 

TGL

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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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