Wind
 

I hate the wind. Just completed my daily ride with a 2 mph lower average speed than I have been due to the wind.

This motivated me to do a bit of reading. I always knew that in an out and back course any wind, no matter the direction, would lead to increased completion time, but never really put too much thought in to it. On a very basic level, one would intuitively think that the tailwind would make up for the headwind, but this is not true.

Here are some nice graphs. I particularly like the last one. A 25 mph wind at 0 degrees to the course increases completion time by ~22 minutes on a 25 mile out and back course.

Sure, everyone knows that wind is bad unless you are going one way with a tailwind, but this helps understand just how bad it is.

HED has a cool tool for calculating the Apparent Wind.

http://www.hedcycling.com/aerodynami...calculator.asp

All of this basically just confirms what every cyclist already knew, the vast majority of winds are headwinds.

Hmmm...that is interesting. I ride in the drops against wind, it seems to help.

Wind is one thing, but when combined with heat it feels like I'm riding in a convection oven.

Anything to reduce the effect of the wind definitely helps. But even so, in an out and back course, any wind will increase your completion time as compared to no wind.

Kinda cool, although it would be cooler if it could estimate speed loss due to wind resistance for a rider given weight, height and position (I know it would be rough).

Yeah, although it might not be apparent to everyone. Also, it's hard to estimate the effect that the wind actually has on speed. My reason for posting is mainly that I was surprised there would be such a noticeable effect on an out and back course.

Intuitively, it is pretty clear that you spend more time going against the wind than with the wind for an out-and-back course, so you can't possibly make up the lost time.

IMO, this is the major disadvantages of tracking rides and performance based on average mph.

Right, but what I'm saying is this (with really rough numbers):

No wind entire distance: 20 mph average.

Tailwind half distance: 25 mph average.

Headwind half distance: 15 mph average.

Total average: 20 mph.

I understand you will spend more time in the headwind, but you partially made up for that lost time (vs. zero wind) when you had the tailwind. The point I am making is that I underestimated the effect of a constant wind on an out and back course.

Lol. I had that exact thought near the end of my ride. Maybe I'll spring for a power meter at some point.

double post accident

You're doing it wrong. You have to use time not distance.

20 mph, 20 miles = 1 hour
average speed = 20 mph

25 mph, 10 miles = 24 minutes
15 mph, 10 miles = 40 minutes
average speed = 18.75 mph

the math doesn't work like that. Take a 25mile TT (essentially 40K) Rider one does 20mph out and back with no wind. His time is 1:15.

Rider 2 with a wind on the course does 25 miles an hour out, and 15 miles an hour back, Rider 2's time is 1:20

Rider 2 only averages 18.75 mph.


So part of the problem is as UMD says, you spend more time going into the headwind than you save with the tail.

Then in the real world, the second part of the problem is that for every wind angle other than 0 and 180, the fact that cross winds present themselves as more of a headwind when the force vectors are taken into consdieration. That's the point of the HED tool.

But I am saying that *intuitively* you can't think has half the distance. Average speed is total distance / total time. You spend a lot less time going 25mph for half the distance than 15mph for the other half the distance and therefore the average has to be less than the no wind average. That's not taking into account that a 10mph wind doesn't affect each direction equally either...

Yeah, when I typed out my post I was thinking time, but typed distance.

When I said "On a very basic level, one would intuitively think that the tailwind would make up for the headwind, but this is not true", that basically means "considering it for 2 second during the ride."

I understand what you are saying, but IMO it isn't apparent when thought about briefly during a ride, given no prior thoughts / research on the subject.

I get what you are saying, that without much thought.

It's the same for hills, at least for me.

In addition, a headwind hurts your road speed more than an equivalent tailwind helps it.

The power required to overcome aerodynamic drag increases with the square of the speed increase. So, given the same power output, even though your "airspeed" decreases with the tailwind just as much as your "airspeed" increases with the headwind, your road speed is decreased more by the headwind than it is improved by the tailwind.

I have been training for an upcoming Duathlon and I have been timing myself (tracking in a spreadsheet)on a loop just over 4 miles in my neighborhood. I also noted the conditions with wind speed and direction. I thought for sure that winds at my back up most of the climbs would give me a better overall time....not true. My best times are always on calm days.

This is strange. I mean sure, I get frustrated by the wind, but I know I'm working harder, therefore getting a better work out, no?

HTFU?

Just because it is not "intuitive" to you does not mean it is not blindingly obvious to others...

Yes, I didn't want to muddy the waters with that more complex discussion. But I did cover it in my next post:

I invite you to ride in the country in Nebraska (or myriads of other windy areas). You will be more than frustrated at times. I have been in headwinds on flats where 10mph in the drops was still a good workout.

Wind would be considerably more tolerable it if wasn't so deafening.

God, I love it when you talk dirty.

Whatta buncha noobs. This is why we have wives / girlfriends. Ride the tailwind with your buddies, have the missus come pick you up.

Yeah, I hear ya for sure. We have this crazy wind that comes off of these giant bodies of water called the Great Lakes here. I'm no stranger to huffing and puffing just to stay above 10mp/h! It's demoralizing, but hell, you sure do appreciate calm days when you're doin' 20+mp/h effortlessly.

+1! I wish earplugs didn't make me feel like I was in a bubble. I'm sure there's hearing loss associated with this.

welcome to my world