September 24, 2017 Login  


Aerodynamics!
Last Post 05/12/2017 07:20 AM by Cosmic Kid. 14 Replies.
Printer Friendly
Sort:
PrevPrev NextNext
You are not authorized to post a reply.
Author Messages
79pmooney

Posts:1725

--
05/08/2017 01:48 PM
A good article on excellent research on descending positions, esp those of Froome, Sagan and Pantani as well as more conventional positions.

https://www.linkedin.com/pulse/which-cyclist-hill-descent-position-really-superior-froome-blocken

It's a myth buster.  (I like it because it compares in wind tunnel testing and computational fluid dynamics.  I never got to do wind tunnel testing, but Michigan had a towing tank to test ship models in and I spent my high school last winter doing a project at MITs water tunnel.  (Same as a wind tunnel but because the "air" is so much heavier, you can use much smaller models and wind speeds.) I took a course in grad level fluid dynamics and the math to go with it at Michigan.  Now in 1975, we did not have the computational power to run the huge model of this study.  In fact, we didn't even have the computational power to create that model.  But the math and the theory were all there and it fascinated me.  Seeing the math match the physical very closely - wow!  On a shape that is not simple.

Spoiler - Froome's very dangerous postition not only isn't for kids, it isn't what you want if you really want to win.

Ben
Dale

Posts:923

--
05/08/2017 02:29 PM
His descending position or the constant gawking at his stem?
79pmooney

Posts:1725

--
05/08/2017 03:09 PM
His descending position. (I think that is the only time thie road ahead gets his full attention simple because he CAN'T see his little black box.)

Ben
Cosmic Kid

Posts:2141

--
05/08/2017 04:38 PM
You guys want me to chime in now or wait until later to mention how important aerodynamics are?

I'm pretty surprised that the Pantani descending position tested fastest.....intuitively it seems like ti would be the least efficient.

I think one apsect of this study that is up to debate is the efficiency of these positions according to rider size, shape, etc. It would not surpris eme in the slightest if what works well for one rider is very inefficient for another rider (much the same as one helmet tests well for one rider and can be horrific for someone else). Similarly, I wonder if helmet shape could change the test results for a given position?

I didn't see it in the article, but did they base their modeling on the riders pictured (i.e. Froome, Pantani, Nibali, etc) or did they standardize to a particular rider?
Just say "NO!" to WCP!!!!
Orange Crush

Posts:1982

--
05/08/2017 09:39 PM
They took one rider, had him adopt the different positions then made scale models.

And fully agreed on how different positions may work better for different riders. Feelwise anyway.
Red Tornado

Posts:147

--
05/09/2017 01:40 PM
Posted By Dale Dale on 05/08/2017 02:29 PM
His descending position or the constant gawking at his stem?


Yes.
Cosmic Kid

Posts:2141

--
05/09/2017 01:55 PM
I also wonder how rider weight could affect the different positions. Seems to me that a position always *felt* faster the farther you got your weight over the front wheel (yes, that is a subjective evaluation, which is a dangerous assumption). So is it possible that a heavier rider could have a faster descending position ala Froome vs. the Pantani position?

Dunno...just tossing it out there. An interesting study no doubt, but a lot ovavariables make it pretty hard to make any conclusive, authortative statement that "XX position is the best".
Just say "NO!" to WCP!!!!
79pmooney

Posts:1725

--
05/09/2017 03:39 PM
CK, the news from this study that I like is that the old fashioned stay on your seat but get as low as you can isn't too far off. Good news for those of us who treasure both our life and our manhood.

I do sacrifice a little aero to include my teeth in that picture, offsetting my head enough that a bump will not crack my chin and loose me a few.

And CK - "ovavariables"? I don't think ovaries are an issue here!

Ben
Orange Crush

Posts:1982

--
05/09/2017 05:16 PM
It doesn't need to be fast, it just needs to look pretty. And when like me you're on the wrong side of 25 those fancy positions are becoming a bit of a pain in the neck...literally [URL=http://s1378.photobucket.com/user/Jos_Beckers/media/6-HAUTE-ROUTE-ALPES-2015-FV-385_zpsurrgdsdt.jpg.html][/URL]
79pmooney

Posts:1725

--
05/09/2017 09:58 PM
CK wants to know: is that the stand in for Cancellara for the wind tunnel test in that photo?

Ben

PS Orange, that photo's a keeper! I envy you.
Orange Crush

Posts:1982

--
05/10/2017 04:31 PM
Posted By 79 pmooney on 05/09/2017 09:58 PM
CK wants to know: is that the stand in for Cancellara for the wind tunnel test in that photo?



No...the non-conforming left ear would skew wind tunnel results.
79pmooney

Posts:1725

--
05/11/2017 11:00 AM
I bet a lightweight headband would gain you a few watts. I am sure CK could come up with the numbers. (If it were me, I'd just say it's there to keep my RPM under control on big descents; a fix gear thing.)

Ben
Cosmic Kid

Posts:2141

--
05/11/2017 03:29 PM
I am sure CK could come up with the numbers.


The answer is ALWAYS ~10 watts. New tires? 10 watts. Aero bike computer? 10 watts. Shoe laces instead of straps / BOA? 10 watts. New ZIPP NSW wheels vs. Firecrest design? 10 watts. Using a headband to reign in a non-conforming left ear? Yup....10 watts.

/sarcasm
Just say "NO!" to WCP!!!!
79pmooney

Posts:1725

--
05/11/2017 10:32 PM
Shoe laces? 10 watts? I spent $10 on grommets and laces to retrofit the shoes whose straps had been such an issue for my feet. Loved them from the first ride. But I was under the illusion I was faster because I could finally ride pain free. No, it was that investment of $1/watt that made a the difference.

I'm going to lace up more of my shoes. This is to good.

Ben
Cosmic Kid

Posts:2141

--
05/12/2017 07:20 AM
I just got a pair of Giro Empire ACC shoes w/ laces. 50% off, plus and additional 20% off w/ coupon. $275 pair of shoes that cost me like $110. Shoes are super comfy.

There is a pro triathlete who tested these shoes (cut out the tongue and used elastic laces for fast entry) and they tested 10w faster for him. Specialized has also tested their lace-up shoes and they test very fast, as well.

I'm gonna try and remove the laces and use those "Sweet Spot" rubber straps that kids put on their soccer cleats to tech them how to properly kick a soccer ball.
Just say "NO!" to WCP!!!!
You are not authorized to post a reply.

Active Forums 4.1
NOT LICENSED FOR PRODUCTION USE
www.activemodules.com

Latest Forum Posts
Wow! The voters have spoken posted in Professional Racing

World's course and pics posted in Professional Racing

Ugh posted in The Dark Side

A Double Century a Day - for 14 Months! posted in The Coffee Shop

Didn't see this coming posted in Professional Racing

Another doping report posted in The Dark Side

Vuelta WOW posted in Professional Racing

No articles match criteria.
  Terms and Conditions | Privacy Policy  Copyright 2008-2013 by VeloNation LLC