I saw a streetsweeper leaving around 6:15am or so. Initially, this seemed like a good idea to move any sand asside but the combination of the water on the sweeper, the brushes and sand meant it got smeared across the road.
Those are cool photos.
Hey Sergio, Are those FMB silks your running? I just ordered $1200.00 worth of FMB tires. Half Competition CX’s for the road and half Records for TT’s.
Sure. I would guess that the water droplets add drag. At the very least they weigh you down with a few pounds of water condensed on your skin and clothes.
But primarily it’s going to affect your confidence regarding speed carried in to a blind section of heavy fog or the corners.
But I would LOVE to race in these conditions. It would be great.
In theory, I would say yes. In dry air, aerodynamic drag is the reaction force caused by accelerating the surrounding air in the direction of your motion through it. But with air, you are only accelerating it to some fraction of your forward velocity. The water droplets in fog that don’t get out of the way and stick to you or your bike need to be accelerated all the way up to your full velocity. When the water evaporates, you don’t get any of that energy back. This loss is in addition to the aerodyamic drag which is still present. So this is an additional penalty you must pay when there is fog (or anything else suspended in the air like bugs).
As far as how much it slows you down, I have no idea how to compute how big the effect is. Was there a noticeable difference in overall performance in this event?
As far as how much it slows you down, I have no idea how to compute how big the effect is. Was there a noticeable difference in overall performance in this event?
For me there was…seemed to be “worth” ~.010 m^2 of CdA according to my quick look at it last night…or, on the order of ~10W at race speeds.
OK, I found a ref that states that fog contains 0.05 to 0.5 grams of liquid water in a cubic meter of fog. So for the sake of using round numbers, lets conservatively assume the fog you were in was at the low end, say 0.1 g/m^3.
Let’s also assume you are not going that fast, say 10 m/s (36 km/h), and your frontal area is 0.5 m^2. So then you would sweep out a volume of 5 cubic meters per second (10 m/s * 0.5 m^2 = 5 m^3/s).
Assuming none of the water droplets get out of the way, you would be collecting water at the rate of 0.5 grams per second (5 m^3/s * 0.1 g/m^3 = 0.5 g/s).
Accelerating this water to your speed would require 0.25 watts ( 1/2 * 0.5 g/s * (10 m/s)^2 = 25 gm^2/s^3 = 0.25 kgm^2/s^3 = 0.25 W).
Even if you were riding through the thickest fog at a higher speed, there is no way you were losing 10W to the fog. Now, if the roads were wet, you may have lost another few watts to rolling resistance, but they would have to be really soaking wet to take up 10W, I think.
It would be interesting to look at riders who had a power meter to see if they may have lost some power due to cooling load in 100% humidity.
The course record was set on a day with similar weather conditions. Broken the following month again at 24:36.
(I coached Shawn to the record that year, and he borrowed my bike) http://www.socalcycling.com/news/2007/feb07.asp
Shawn Olin breaks 8 Year Fiesta Island Time Trial Record
2/11/07 - The record set by Olympic cyclist Shaun Wallace on 9/12/1999 in 25:12 was broken today in 25:05 (20k/original long course), 29.72 MPH avg speed, by DeWalt Racing CAT 1 cyclist Shawn Olin in the wind, rain and mud on a custom built Tiemeyer pursuit fixed gear bike with 175mm FSA track cranks, Vision aerobars, Blackwell Research track disc/100mm wheelset, and Dura Ace front brake. He ran a 52x13 gear and spun over 90RPM, having had to come out of the aerobars in each corner due to the slick muddy conditions. Shawn is the 2004 US Military Time Trial National Champion.
Great pics serg almost as good as this one. In fact designed to be aero. Check out the natural airfoil design.
Where did you catch that striper?
Don’t make get into that topic. 
Have you ever heard of Mike Fixter?
Sergio
Hi Sergio…good to see you again yesterda!
Yes, humid air is less dense than dry air…but, my suspicion is the limit of that being an “advantage” ends where you have suspended droplets of water in the air. Liquid water is MUCH denser than any kind of air 
I recall looking down at my bars during the TT and watching the huge droplets form on all of the leading edges…and then being half-mesmerized by the “flow viz”
According to my power vs. speed…those were apparently slow conditions…
My bike needs to be washed. It looks like I rode it in the rain.
Lots of sand also on Sergio Jr’s.
I think Sergio lost a good amount of power to gain in CdA. Alex Simmons (who has been coaching him in the last month estimated his CdA ~ 0.205^2) Had he mantained the power of his first race at FI he would have won rather easily. Instead he finished second overall for the second time in a row. Again for a few seconds.
He also did some usual (in his last days) 17 year old mistakes (like racing with a loose crankset) and a few others that may have taken away some more seconds.
Plenty of data to be revised. The reason I asked about the fog, was because it was an unusually foggy day (at least for us). It was more than just humidity as someone else mentioned. I doubt we can get the funds to do a paper to be published on this topic .
Sergio
Hey Sergio, Are those FMB silks your running? I just ordered $1200.00 worth of FMB tires. Half Competition CX’s for the road and half Records for TT’s.
No… The front one is a Vittoria Pista EVO CS tubular. Fastest tubular AFM tested on his last Crr chart. That front wheel is Sergio Jr’s track Pursuit wheel. That course is apparently clean enough to use them there. They are very fast tires, but I would not dare to used them on a normal course. The rear one is a Vittoria Corsa EVO CX, his normal TT tire.
I have been tempted to try FMB’s but I really like the Pista EVO tubulars for the track… and occasionaly for a TT. The testing opportunities are scarce, so please keep us informed about those FMB tubulars.
Sergio
The course record was set on a day with similar weather conditions. Broken the following month again at 24:36.
(I coached Shawn to the record that year, and he borrowed my bike) http://www.socalcycling.com/news/2007/feb07.asp
Shawn Olin breaks 8 Year Fiesta Island Time Trial Record
2/11/07 - The record set by Olympic cyclist Shaun Wallace on 9/12/1999 in 25:12 was broken today in 25:05 (20k/original long course), 29.72 MPH avg speed, by DeWalt Racing CAT 1 cyclist Shawn Olin in the wind, rain and mud on a custom built Tiemeyer pursuit fixed gear bike with 175mm FSA track cranks, Vision aerobars, Blackwell Research track disc/100mm wheelset, and Dura Ace front brake. He ran a 52x13 gear and spun over 90RPM, having had to come out of the aerobars in each corner due to the slick muddy conditions. Shawn is the 2004 US Military Time Trial National Champion.
That is a very fast time Gary.
Next time Sergio will race the course in his Pursuit bike (if it is still allowed). It will be interesting to see how much he can lower his 25:57 time on Fiesta Island on a T3 instead of a P3. It will alseo be fun for him to do 20k instead of 3k on that bike. But I will make sure he tries that after September .
I was looking for you last Sunday but apparently you were not there. The first time we visited FI you were there, I saw you on the tandem but was not aware that you were the one racing on it. We are leaving Wednesday to Phoenix as Sergio will race VoS, but after that he will return in 3 - 4 weeks and will be based in San Diego to train for a few weeks and do some more races.
There are so many variables that estimating the effect of fog (or rain) on a ride is very difficult, but I would love to see the results of some serious research on this topic.
Sergio