Go Back  Bike Forums > Bike Forums > General Cycling Discussion
Reload this Page >

Calculating side winds

Notices
General Cycling Discussion Have a cycling related question or comment that doesn't fit in one of the other specialty forums? Drop on in and post in here! When possible, please select the forum above that most fits your post!

Calculating side winds

Old 10-19-10, 04:25 PM
  #1  
Senior Member
Thread Starter
 
TomD77's Avatar
 
Join Date: Jul 2010
Location: Florida Panhandle
Posts: 572
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Calculating side winds

I don't carry an MP3 player or anything else with me on rides so I have thinking time. You would think that a wind coming from your 9:00 or 3:00 position would have no effect on your speed or effort but it sure doesn't feel that way when you get hit by a gust from the side.

Just playing with even numbers, say you're riding at 20 mph and there is a 10 mph wind at your 3:00. The felt wind will be 22.3 mph coming from your 1:00. Keeping numbers round, instead of having to bore a hole in the air at 30 feet per second, the hole is bored at 33.5 feet per second. Considering that the energy cost of moving air out of the way increases as to the square of your velocity, the side wind cost you 25% more effort to maintain speed. Things get worse rapidly as the wind shifts to your front but the wind probably has to be from 4:00 or further back before it doesn't cost you.

If there are any errors in my reasoning, I'd like to know it.

I live in northern Florida where there are relatively few days through the winter where it is too nasty to ride but there sure is a lot of air in a real hurry to be somewhere else.
TomD77 is offline  
Old 10-19-10, 05:34 PM
  #2  
Senior Member
 
BlazingPedals's Avatar
 
Join Date: Dec 2004
Location: Middle of da Mitten
Posts: 12,473

Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, Catrike Speed

Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1511 Post(s)
Liked 732 Times in 453 Posts
That pretty much sums up 'standard wisdom.' Which is why a wind always hurts you on a loop-type or out-and-back ride where you end up at the same place you started: The wind really is against you more than it's with you.
BlazingPedals is offline  
Old 10-19-10, 05:46 PM
  #3  
CRIKEY!!!!!!!
 
Cyclaholic's Avatar
 
Join Date: May 2005
Location: all the way down under
Posts: 4,276

Bikes: several

Mentioned: 37 Post(s)
Tagged: 0 Thread(s)
Quoted: 1589 Post(s)
Liked 687 Times in 365 Posts
In your scenario I make the apparent wind 22.4mph from 26.6 degrees off your heading (just shy of your 1:00) so your numbers are good.

I understand how much the wind sucks, especially now that I mostly commute on my lowracer recumbent. We get the afternoon nor-easter here in summer which blows consistently most days and peaks in strength right at my home commute time which happens to be directly into it along a long, exposed stretch of freeway. I often cruise by groups of hardcore roadies pacelining into that headwind and recall how frustrating some of my commutes used to be. These days I save the fully fendered Surly for the rainy days.

Edit: I'd kill for a NoComm along that commute... one day maybe
Cyclaholic is offline  
Old 10-20-10, 10:39 AM
  #4  
Time for a change.
 
stapfam's Avatar
 
Join Date: Jan 2004
Location: 6 miles inland from the coast of Sussex, in the South East of England
Posts: 19,913

Bikes: Dale MT2000. Bianchi FS920 Kona Explosif. Giant TCR C. Boreas Ignis. Pinarello Fp Uno.

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Likes: 0
Liked 5 Times in 4 Posts
Stop thinking- I now have a headache wondering what else you get up to on rides.
__________________
How long was I in the army? Five foot seven.


Spike Milligan
stapfam is offline  
Old 10-20-10, 01:07 PM
  #5  
Senior Member
 
Join Date: May 2005
Location: Flagstaff, AZ
Posts: 976

Bikes: Marin Pt. Reyes, Gary Fisher HiFi Pro, Easy Racers Gold Rush recumbent, Cannondale F600

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times in 0 Posts
Learned about the apparent wind early as a kid while racing small sailboats. Seems unfair that the faster you go, it just rotates closer and closer to your nose!
rnorris is offline  
Old 10-20-10, 01:26 PM
  #6  
Senior Member
 
Shimagnolo's Avatar
 
Join Date: May 2008
Location: Zang's Spur, CO
Posts: 9,085
Mentioned: 11 Post(s)
Tagged: 0 Thread(s)
Quoted: 3351 Post(s)
Liked 5,400 Times in 2,796 Posts
Click on "Apparent Wind Calculator": https://www.hedcycling.com/aerodynami...calculator.asp
Shimagnolo is offline  
Old 10-20-10, 02:48 PM
  #7  
Senior Member
Thread Starter
 
TomD77's Avatar
 
Join Date: Jul 2010
Location: Florida Panhandle
Posts: 572
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 1 Time in 1 Post
Originally Posted by Shimagnolo
Click on "Apparent Wind Calculator": https://www.hedcycling.com/aerodynami...calculator.asp
Hey thanks! That's handy. Why worry about vectors and trig when a java app can do it as fast as you can frame the question?

Playing around with it just confirms my intuition, wind isn't your friend. Other than biking, I have two other main hobbies: long distance target shooting and offshore fishing and a good wind will wreck a day of either.
TomD77 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
RFEngineer
Road Cycling
105
03-21-18 07:58 AM
cncwhiz
Commuting
38
06-25-16 09:53 AM
Gresp15C
Commuting
37
12-15-15 12:27 PM
dramiscram
Commuting
50
10-31-12 08:59 PM
jalbri
General Cycling Discussion
32
01-09-10 02:51 PM

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.