No, it wouldn't quite be like that. Those watt savings are all at 30mph.

So, only in cases where the course is flat and you can go 30mph would it be equivalent to gaining 30-45 watts

Also, the Zipp404FC is a 15 watt savings only at certain yaw angles compared to certain really bad wheels.

A better way to think about aero savings is to use the rule of thumb:

50grams of drag at 30mph == 5 watts at 30mph == .5 seconds saved per kilometer at any speed

and of course that rule of thumb will only work pretty well if the course isn't too hilly, or technical!

---

---

Kat Hunter reports on the San Dimas Stage Race from inside the GC winning team
Aeroweenie.com -Compendium of Aero Data and Knowledge
Freelance sports & outdoors writer Kathryn Hunter

No, you have not changed your power. But aerodynamic choices allow more of those watts you generate to generate speed rather than fighting your biggest resistance which is air (in essence)

To get a visual representation, take a spring scale and attach a fishing line. Then fix the line to a narrow bottle of water and drag it thru a pool. You'll see about 1 to 2 newtons of force or drag on the scale. Then do the same with a small square box. You'll see about 3-4 newtons of force registering on the scale.

That illustrates the increase in force to overcome the greater drag. Same as you - aero improvements to your position and equipment mean less force or power fighting drag and more to speed all else being equal.



J

Bit of an explanation on how the numbers scale to real world here http://speedtheory.co.nz/...-frame-aerodynamics/

Ok. Yaw and drags are a little above my head. But I get the gist of it.

If only everything we touched turned to gold like that.

It's about the balance between energy supply and demand.

e.g. improved aerodynamics means for the same energy supply you can go faster.

So how much faster should I expect to go if I had all those? Assuming flat terrain, my weight = 171 lbs, bike = 20lbs, no wind

anyone know the rough calc for :

Zipp 808 tu front vs DA 7850tu front
+ shaved legs ?

total over 20km assume a flat course.

---

Training Tweets: https://twitter.com/Jagersport_com
FM Sports: http://fluidmotionsports.com

How are you measuring power? 19 mph @150 watts for a 170 lb person does not seem right, esp if not already aero'd out.

Take a look at this picture and it will give you a very good idea about time savings for each item.

http://cyclingtips.com.au/...ime-trial-equipment/

What I found interesting is that the shoe covers save more time than an aero frame and disc rear wheel.

---

--------------------------------------------------------

Check out Analytic Cycling online - free tools to measure exactly that kind of question.

I have a powertap. Not sure why you don't think it is right. Is it too high or too low? I don't know how to post a pic, otherwise I would post the data from my garmin. But you can check yourself at analytical cycling site. 68", 171 lbs, no wind, 100 ft above see level, 0 incline, and cadence of 88. At 150 watts, I should be 19.5 mph. I must be creating a little more drag.

Thank you. Very interesting site.

As some of the others have said, you are not 'gaining watts' you are saving drag. Aero gains are often reported as watts because that is what the industry is currently throwing at you. As jackmott said it is grams of drag that are important and the faster you go the more and more those small reductions start to make a big difference.

@ 19mph adding a set of good aero wheels (from bad 32h box rims) and a good helmet for your position plus making your legs slippery I would not be surprised to see a 1-1.5 mph increase depending on the day at the same nominal power.

---

This is your life, and it's ending one minute at a time. - Fight Club
Industry Brat.

"Not sure why you don't think it is right. Is it too high or too low?"

I would say 150 watts would seem low for 19 mph but it sounds like it's pretty flat where you ride so perhaps that is skewing my perception.

Seems in the ballpark to me with an average, not too aggressive position. I pulled up a training file a couple weeks back where it was hot & humid, I was lost, crushed from a hard training block and out of water and nutrition and close to bonking.... With mostly a moderate cross wind, rolling terrain, I rode 20.1mph @ 156W AP,167W NP. Training set-up with box rims, road helmet, but not my gatorskin rear. But i ride a fairly aggressive position, and am 164, 5'11". Height and general size, makes a bigger difference than weight itself. In race kit, that probably jumps to 21.5mph.

Keep working on aero improvements. I've really surprised myself this year. I consider myself a Slowtwitch aero approved success story. I've done some "B" races where I suspect (didn't have a PM last year) that my power was the same as last year, but better pacing and bike set-up has shown big gains. Rode a 1:00 flat on a fairly hilly (650ft) Olympic, with a non-favorable wind at 260W AP recently. If I rode it at goal watts I would have gone at least 90" faster.

---

TrainingBible Coaching
http://www.trainingbible.com

Florida. Flat as a pancake!

Thanks. I've been working on getting more aggressive with my positioning. One problem has been hip flexibility. It's getting easier to be more aggressive though.

Fixed that for you...plus added the CdA portion since that's infinitely more useful than "grams of drag" ;-)

---

http://bikeblather.blogspot.com/

I solved that with shorter cranks and a noseless saddle so I could rotate my hips further forward. I'd probably a good 3" lower in the front than where I was when I first got my bike in 2011, but with a more open hip angle. Low in the front doesn't have to mean folded over and crunched up. It will still take some neck flexibility to see down the road which can take weeks or a couple months to adapt to depending on how frequent and how much your ride. Actually most of the time I'm only looking probably < 1/4 mi down the road anyway and lowering my neck ("turtle-ing") to keep my helmet tail flat to my back per advice on here.

---

TrainingBible Coaching
http://www.trainingbible.com

This thread is a good example of why drag should be measured as CdA. Forget about the other supposed measures that confuse nearly everyone... because they require defining other variables that were either forgotten or never defined in the first place. I've seen people who are pretty sharp with this stuff make errors repeatedly.

There are a million calculators available online where you can take the CdA number and and apply it to whatever situation you like to determine how much difference it makes to your speed or time.

Or if it is flat course you can use this relationship: V2=V1*(CdA1/CdA2)^.37 and be real close.

This is really interesting. I wonder why it is not more often pointed out that, not only the biggest bang for the buck, but the greatest actual time savings comes from three of the cheapest items on the list. Given that most people cannot generate the speed over a full triathlon to realize the benefits of most of this stuff, I find the ongoing debates, and the expenditures, for the pursuit of aero to be quite amusing. Especially when it seems most people spend over half of the ironman "run" walking. What was that saying about a fool and his money?

You didn't read the stuff above in this thread, huh?

---

http://bikeblather.blogspot.com/

What is a full triathlon?

I somewhat agree with what you are saying, but there is another way of looking at it. Let's say that you don't increase your speed but average 50 fewer watts during the bike. That will allow the individual to "run" a larger portion of the marathon.......I hope.

---

--------------------------------------------------------