Good CdA for tall triathletes

Dec 16, 18 15:38

Post #1 of 49 (10783 views)

With wind tunnel tests, velodrome tests and field tests it's becoming more and more common to see CdA statistics being quoted. On here I often see triathletes quoting CdA stats of 0.2-0.22, which from what I've seen is smaller athletes with refined positions and good equipment.

Using bestbikesplit I have begun trying to get some baseline data which I can hopefully improve on. My initial efforts indicate in the range of 0.27. For context:

- 47 year old male
- 6'2" (188 cm) 180 lbs (82 kg)
- 56 cm 2007 Cervelo P3C
- no risers, low profile aerobars, 130 mm stem
- non-aero spokes training wheels used in baseline testing (race with old narrow toroidal Zipp 404 and disc cover)
- standard vented helmet (race with long tail Spiuk)

Im not sure how accurate the intial 0.27 data points are but I am sure that as I collect more data and get more experienced I'll have more reliable baseline data and will hopefully improve on it.

Out of curiosity what is a good CdA for a 6'2" (188 cm) or taller triathletes shoot for? What kind of #'s would Jordan Rapp, Torbjorn Sinballe, Bjorn Andersson or Slowtwitch poster Eric Reid get for CdA?

Last edited by: kbd: Dec 16, 18 15:38

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 16:07

Post #2 of 49 (10743 views)

Here is a reliable number from Jordan

Having seen many CDAs from many people from Pro tour guys to Joe Bloe, I take all quoted numbers with a grain of salt but Jordan's makes sense

Last edited by: marcag: Dec 16, 18 16:08

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 16:27

Post #3 of 49 (10716 views)

I'm 6'0, 170 and about a 0.21-0.22 (raced st As in 1:02 on 204w, 220np)

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 17:03

Post #4 of 49 (10680 views)

I'm 6"2', 180 lbs with wide shoulders and the best I have done with BBS aero analyzer is 0.25. I was put through the Stac virtual wind tunnel and there were no obvious improvements to be made other than tucking my head more. I'm thinking i'm close to my limit without actually going to the wind tunnel.

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 17:27

Post #5 of 49 (10651 views)

-6'1"
-175lbs
-wide chest/shoulders (42" chest)
-long arms (6'4" arm span)
-cda .215 without an overly "aggressive" (low) position.

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 18:08

Post #6 of 49 (10619 views)

kbd wrote:

What kind of #'s would ... or Slowtwitch poster Eric Reid get for CdA?

great, another opportunity for eric to post that random oblique shot of himself in the wind tunnel...

you're gonna get numbers that are all over the place. what you should shoot for is a position you can hold that minimizes waste. some of the posters that have responded may be aero, but that says nothing about their overall race results. the important time is the finishing time. be as aero as you can be to be efficient but sustainable, and run fast.

Re: Good CdA for tall triathletes [jkhayc] [ In reply to ]

Dec 16, 18 19:14

Post #7 of 49 (10564 views)

jkhayc wrote:

...what you should shoot for is a position you can hold that minimizes waste. some of the posters that have responded may be aero, but that says nothing about their overall race results...

I agree with you a comfortable and efficient position is necessary. A position that tests well but is unsustainable on race day is meaningless. My subjective assessment of my self, is that my current position is comfortable and can ride in the aerobars as long as I want to.

You are absolutely correct that race results are what matters. Race results are what I am shooting for. My Ironman PR was in 2009 at 38 years old in 9:56 with a 5 hour flat bike split on a Cervelo P2SL, my wired PowerTap had unfortunately quit working earlier in the year, so no data to compare. My goal is to try and go sub 10 again in 2021 as I enter M50-54. Older with *slightly* nicer equipment. Bestbikesplit is a great tool that can potentially help me achieve my goal. Assessment of and improvement of CdA can be helpful in trying to beat father time. Just trying to gain context on good values of other triathletes of similar size.

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 19:24

Post #8 of 49 (10554 views)

barring any mobility/structural issues, you should be able to achieve something like .22 - .23 without going on a crazy spending spree. height is less of an impact to cda than is width.

Re: Good CdA for tall triathletes [jkhayc] [ In reply to ]

Dec 16, 18 19:38

Post #9 of 49 (10540 views)

Cool, thanks for offering some perspective. Sounds like I've got some experimentation ahead of me.

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 20:22

Post #10 of 49 (10506 views)

6'3", 180lbs -- 0.189

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 21:03

Post #11 of 49 (10476 views)

0.21856783 /pink

Last edited by: Tom_hampton: Dec 16, 18 21:03

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 16, 18 21:03

Post #12 of 49 (10475 views)

I'm 5'11" and 83kg my cda is 0.21 in a skin suit and aero helmet. I might be better on race day with my H3 on the front and faster tyre than on my Mavic training wheel. (garmin hub speed sensor)
I'm sort of lucky as I have 31' legs so I sit very low and long on the bike.

Re: Good CdA for tall triathletes [motd2k] [ In reply to ]

Dec 17, 18 1:12

Post #13 of 49 (10395 views)

Would be interesting to see pictures of your position and also for others posting CdA value :)

Re: Good CdA for tall triathletes [roa11] [ In reply to ]

Dec 17, 18 4:43

Post #14 of 49 (10292 views)

http://www.ttlegends.org/wp-content/uploads/photo-gallery/.original/ALLONBY%20DAVID%20FFJ.jpg

Clearly some of those bits won't transpose nicely into Triathlon, the overshoes in particular, but the rest (except the helmet which is basically just guesswork unless you get yourself tested) would be a good starting point for someone of a similar build.

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 17, 18 9:53

Post #15 of 49 (10156 views)

I'm younger than you, but everything else being about equal, I'm at 0.22 in field testing.

Re: Good CdA for tall triathletes [jkhayc] [ In reply to ]

Dec 20, 18 8:04

Post #16 of 49 (9968 views)

I decided to write a blog on my journey and process of improving my aerodynamics. I have some pictures showing a historical perspective of my position as well as current position as seen on a trainer. Any feedback is welcome.

https://kbdproject.tumblr.com/...ective-on-my-project

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 20, 18 8:10

Post #17 of 49 (9956 views)

All I can offer for feedback is "holy crap that looks uncomfortable."

There's a lot going on here. Wrong saddle most likely, potentially wrong size bike.

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 20, 18 8:12

Post #18 of 49 (9951 views)

Your head looks lower than your back. Might be able to put out more power for equal or better CdA if you raise your front end. Also, your shrug in your pics of you on the trainer is much better than the one in your race pics.

Re: Good CdA for tall triathletes [jkhayc] [ In reply to ]

Dec 20, 18 8:20

Post #19 of 49 (9933 views)

Never ridden the mantis position shown just took a couple pics of it out of curiosity since it seems to be gaining popularity and supposedly tests well for many.

The position with more level forearms is essentially the position that I've been riding since 2006. I feel comfortable and have no difficulty holding it as long as desired. Believe it or not, prior to 2006 I experimented with significantly more drop and trial error brought me to current position which I find quite sustainable.

I had assumed that my current position was probably fairly aero, but I am starting to wonder.

Re: Good CdA for tall triathletes [imswimmer328] [ In reply to ]

Dec 20, 18 8:27

Post #20 of 49 (9924 views)

Thanks for the feedback. I have been practicing "turtling" my head and neck for significant sections of each training ride for the last several months. I never even though about it during the time period that those race pictures were taken.

The steer tube on the bike is cut all of the way down. I have a pair of Syntace aero bars which are a high stack bar. I can see how these look and feel.

Re: Good CdA for tall triathletes [jkhayc] [ In reply to ]

Dec 20, 18 8:27

Post #21 of 49 (9924 views)

yeah I'd give him one size bigger P3 classic

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 20, 18 8:34

Post #22 of 49 (9904 views)

kbd wrote:

Never ridden the mantis position shown just took a couple pics of it out of curiosity since it seems to be gaining popularity and supposedly tests well for many.

you're misunderstanding the current trends in bike fitting.

The "mantis" was a UCI constrained position that is actually now outlawed by even more restrictive UCI rules.

Triathletes, on the other hand, aren't constrained by UCI rules. What's happening in the fitting space, at least from my perspective as a fitter, is that people are figuring out the *proper* way to fit on a time trial bike in a position that's not constrained by UCI rules and is comfortable, powerful, and aerodynamic - the three components that make up a good triathlon fit, especially for long course athletes.

As I outlined in this post here, high hands is not actually the point. High hands is an output of a process that's doing something else altogether. Something you're totally *not* doing in your move from your first position to your second as pictured in this thread.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Re: Good CdA for tall triathletes [ericMPro] [ In reply to ]

Dec 20, 18 8:48

Post #23 of 49 (9890 views)

High hands are not the objective. My limited understanding of the mantis trend is that when viewed as a whole of the rider/Bike system that the position of the forearms does not scoop air up into the torso like Jan Ulrich used to do. I do not even consider UCI limitations since I am a triathlete not cyclist.

I used a forearm angled up position in the late 90's for comfort. Unfortunately I have no pictures of that since it was 20ish years ago.

The mantis pics that I took the other day were on a whim and I didn't adjust anything other than the angle of the extensions. I'll gladly take any guidance you can offer with my trial and error process.

Last edited by: kbd: Dec 20, 18 8:55

Re: Good CdA for tall triathletes [kbd] [ In reply to ]

Dec 20, 18 9:34

Post #24 of 49 (9847 views)

I would argue that you're still not understanding, especially if you're using the "mantis" moniker.

When a fit session iterative process outputs high (ish) hands for one of my clients, I have zero interest in how that affects airflow for the bike/rider system as it relates to the hands themselves (ie. the "scoop", or lack of). It's irrelevant. I'm looking at other more low hanging fruit. The trend is not raising hands, it's getting comfortable and more aerodynamic through different means.

For you, I'd get a bigger P3 classic and add more reach. I'm a one trick pony though, I say that for everybody. Unfortunately it's usually always true.

kbd wrote:

High hands are not the objective. My limited understanding of the mantis trend is that when viewed as a whole of the rider/Bike system that the position of the forearms does not scoop air up into the torso like Jan Ulrich used to do. I do not even consider UCI limitations since I am a triathlete not cyclist.

I used a forearm angled up position in the late 90's for comfort. Unfortunately I have no pictures of that since it was 20ish years ago.

The mantis pics that I took the other day were on a whim and I didn't adjust anything other than the angle of the extensions. I'll gladly take any guidance you can offer with my trial and error process.

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”

Last edited by: ericMPro: Dec 20, 18 9:35

Re: Good CdA for tall triathletes [ericMPro] [ In reply to ]

Dec 20, 18 9:47

Post #25 of 49 (9829 views)

Thanks. I will remove the phrase "mantis" from my vocabulary.

I am comfortable and stay in my aero position as long as I want to. My prior experience with up turned forearms was solely for comfort.

So if I understand correctly, the consensus is that my current position is short on reach.

Our Partners

transition-DOT-area-AT-slowtwitch-DOT-com

Advertise with us

©1999-2024 Slowtwitch, Inc., and Slowtwitch.com
Reproduction of material from any Slowtwitch.com page
without written permission is strictly prohibited.