SBR Utopia - OPEN (Page 120)

Frame mount (that thing is a tank, as you say).  They didn't test the speedfil A2.  have you seen results for that?

ETA - that said, I have a good friend that is a 2X Kona qualifier that uses the speedfil frame tank.  It's not about the [insert product here]

The aerodrink tested about the same as a torpedo mounted water bottle between the aero bars.  The seat tube mounted speedfil wasn't that much slower, and the down tube mounted speedfil was quite a bit slower.

But I still scratch my head on the results of the Xlab Carbon wing with 2 bottles.  Compare the tests where they added the CO2 to the wing, but no bag to the test with no CO2 and no bag.  How does adding the CO2 to the wing shave 90 seconds off a 40k?

So I went and looked at the FLO website since I bought the 60.  At 10 degrees of yaw they are showing the 60 has ~50G of drag, compared to a Mavic Open Pro at ~250G of drag.  So am I right to assume that is basically a 20 Watts savings, or have I really oversimplified it?

Good question.  Maybe Marc can answer, but I always thought that drag was also dependant on speed.  So if FLO tests their wheels at 30 mph, and sees a 200g reduction in drag...you may not see that much reduction of drag (in grams) at 20 mph.

I always thought of it like sticking your hand out the window of a moving car.  At 10 mph...you don't feel that much resistance...but at 50 mph, you can feel the wind really pushing against your hand.

So lets say you only see a 150 gram reduction in drag.  That's still 15 watts.  And as Marc mentioned, at slower speeds, it takes less watts to gain incremental speed.  So the overall benefit is still there no matter how fast you're going.

Thanks for the last two pages everyone, the questions and answers have given me a whole lot of thought topics for the next few days.

Kate - You'll do great, you've done the work, don't worry and enjoy Ocala.

Yep. As a matter of fact, in their NDRV description they say on average it's 175g.It's a weighted average of yaw angles.

Then they go on to say that is 1min 10sec = 70sec for  40km

by the formula I showed you 175g / 50g * .5s/km * 40km = 70 sec

I'm not an aero expert, but I think the drag is constant, but the force/power to overcome the drag is what increases with speed. Don't quote me :-)

Do you have any idea how they measure drag in grams?  I was always curious.  My silly imagination always envisioned that it's sort of like holding up a scale horizontally into the wind and seeing how much the wind pushes into the scales surface.  If you make the surface of the scale aerodynamic, it's will get pushed against less.  So at the same time, increasing speed would also increase the amount of force pushing against the surface of the scale.

But again...this is completely my imagination thinking.  I really have no clue.  LOL.

Very cool - thanks Marc.  I expected the benefit to be a bit less than this.

The last 2 pages have been as confusing to me as my son's Honors Algebra homework! 

These numbers are when they take 2 wheels, not on a bike, not with a rider...i.e not real world conditions.

The really important thing is they look cool

Yeah, I try to keep up, but after a while.... poof!

Some people dig the numbers.  It's not really my thing

http://flocycling.blogspot.ca/2011/11/flo-cycling-how-velocity-effects-drag.html

If I'm reading that right, as velocity increases, drag increases.

I don't really understand most of what they post but I love how they explain the math (right or wrong...) behind all this sort of stuff.

Again something I don't really understand but there are graphs in here that calculate drag, time savings etc for their wheels at speeds from 1 to 30 mph and they give the math to back it up.

Agreed, my head is swimming, but I needed this to get my brain more involved in my training.

ha, ditto.  I get the concept but not the math part.  Just tell me the fastest setup.

"Mom, when am I ever going to use this?"

Well now you know. 

Have any of you tried using a rowing machine to help supplement your swim training?  We have one at our office fitness center that nobody ever uses.  I know it won't address anything with form...but just wondering if I were to hammer out a 30 minute session where my arms and lats are burning...would that actually help my swimming fitness?  Or am I simply just burning calories?

We used to do some rowing when I swam, I'm not sure how much it really carries over.  It's going to burn more than your lats and arms though isn't it?  There would be a significant hit to your legs too if I remember correctly.  That may affect your bike and run workouts - at first at least?

I dont know about swimming, but a colleague of mine comes from a competitive track cycling background (he's a Brit, and you know those dudes are CRAZY about track cycling) and he uses rowing regularly to maintain leg/hip flexor strength for cycling.

Hmmm that is interesting!

My hip flexors are notoriously weak. 

For general fitness it helped, but can't really say it did anything noticeable towards swim fitness more than that. The motion was rather different.

Good ol' fashioned Elfin magic, plain and simple.

And from what I understand is that Marc's formula is good for most things, unless dimples are involved. Dimples are proven at certain yaws to create a small tear in the space-time continuum (OK, it is really a trans-dimensional perforated crease, but I don't want to get TOO technical) and actually cause you to take small leaps back in time while you actually move FORWARD in space. Sportstracks is actually working with WTC on a new timing algorithm/mat location in upcoming Ironman races to analyze the true effect dimpled products have, but until then Kate, I think Ben's advice to "roll with what ya got" is the best advice so far.

Drag coefficients will be constant, but the forces will change. Even though grams is technically mass (not force), it'll drop some with reduced speed. However, that doesn't mean all things in that equation will drop as it's not truly an equation. It's a shorthand expression. Time gains can actually go up because of being on the course longer.

And since someone will surely ask, they use the speeds they do because that's what the tunnels can work at reliably and still be at least sort of practical for bikes. They weren't meant for bikes, but more for things like race cars.

Per Fred's question of how good the estimate is, I think the expression works well enough to get a general sense of what happens, but do keep in mind that it's more a rule of thumb.