Contributions to Aerodynamic Drag

[531Aussie]

I am not sure folks enter regular road races with stuff like tri spoke wheels, do they?
!

nah, the last I heard it was a minimum of 16 spokes per wheel for a regular, mass-start race.

 

[chainstay]

nah, the last I heard it was a minimum of 16 spokes per wheel for a regular, mass-start race.

Ok, thanks! By the way, in following some of these links around that you and others have given me, I have generally found the estimates for the total drag lended to the bicycle by the wheelset to be less than the 25% mentioned above---closer to 10% in the articles I have run across. [size=-1]And the Bike Tech review article below seems to suggest that one could expect maybe a 2.4% reduction in drag on a flat course jumping from a 32 spoke box rim to 52mm deep Cosmic Carbones. [/size]

Roughly, the average rider power requirements on a course with a zero net elevation gain is broken down into 60% rider drag, 8% wheel drag, 8% frame drag, 12% rolling resistance .5% wheel inertia forces and 8% bike/rider inertia. In summary, wheels account for almost 10% of the total power required to race your bike and the dominant factor in wheel performance is aerodynamics. Wheel mass is a second order effect (nearly 10 times less significant) and wheel inertia is a third order effect (nearly 100 times less significant). [size=-1]
[/size]

http://www.biketechreview.com/archive/wheel_theory.htm

Here are some quotes from an older article:
[size=-1]

The total drag of the wheels is in the range of 10% to 15% of the total drag on a bike. Drag improvements between wheels can reduce this by 25%, or 2% to 3% of the total drag. [/size][size=-1]The drag on the rear wheel is reduced by 25% due to the seat tube.[/size][size=-1]

http://www.analyticcycling.com/WheelsConcept_Page.html

[/size]
[size=-1]
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[531Aussie]

Ok, thanks! By the way, ..........

I guess the real conundrum is finding out how much faster a $2000 or $3000 wheelset will be, then obviously deciding if it's worth it.

I reckon the wattage differences in the list above are damning, because, after plugging some numbers into the Kreuzotter calculator, it suggests that gaining 15 watts 'at speed' (around 45kph) yields an improvement of only 0.3mph! Selecting "hands on the drops", and leaving every other variable as is (wind speed and direction, etc), I plugged 400w and 415w; 400w gives a speed of 27.7mph, and 415w brings it up to 28mph. Is a $2500 set of Zipp 808s worth that?

I've spoken to heaps of guys who own fancy wheels; some of them are consrevative about the advantages, saying that they might be 1 to 2kph 'at speed' or into strong headwinds, but others swear that they get about a 3kph advantage. Who knows?? If I was guaranteed 3kph at (or around) 45kph, I'd just about sell my family to Mexican bandits to get some 404s

I've been 'banging' on about this because I've go through it myself every few months.

 

[chainstay]

I guess the real conundrum is finding out how much faster a $2000 or $3000 wheelset will be, then obviously deciding if it's worth it.

I reckon the wattage differences in the list above are damning, because, after plugging some numbers into the Kreuzotter calculator, it suggests that gaining 15 watts 'at speed' (around 45kph) yields an improvement of only 0.3mph! Selecting "hands on the drops", and leaving every other variable as is (wind speed and direction, etc), I plugged 400w and 415w; 400w gives a speed of 27.7mph, and 415w brings it up to 28mph. Is a $2500 set of Zipp 808s worth that?

Well it isn't worth it for me right now. Heck, I don't even have a power meter yet, and it would seem kind of backasswards to put $2,000 towards the potential small improvement gains from light, aero wheels even before I have invested much time and money towards improvement from training tools and training methods. But initially I was wondering whether there was much to be said for this relatively inexpensive, so called class of semi-aero wheels with 30mm deep rims, and the answer seems to bet that it depends on the particular wheel and spokes as to whether there is any actual aero improvement over some of the 23/24mm wheels with low spoke counts, and even when there is some aero improvment, it will likely be very, very tiny.

 

[cuervo]

I guess the real conundrum is finding out how much faster a $2000 or $3000 wheelset will be, then obviously deciding if it's worth it.
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.
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I've spoken to heaps of guys who own fancy wheels; some of them are consrevative about the advantages, saying that they might be 1 to 2kph 'at speed' or into strong headwinds, but others swear that they get about a 3kph advantage. Who knows?? If I was guaranteed 3kph at (or around) 45kph, I'd just about sell my family to Mexican bandits to get some 404s
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.
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I wouldn’t give you $2,500.00 dollars for your family, mainly coming from an Aussie who's ancestors where Britain’s most dangerous cons.

Should I say ? naaah

 

[artemidorus]

I wouldn’t give you $2,500.00 dollars for your family, mainly coming from an Aussie who's ancestors where Britain’s most dangerous cons.

Should I say ? naaah

Are you a Mexican bandit?

 

[531Aussie]

Crikey!! A real Mexican Bandit

 

[artemidorus]

an Aussie who's ancestors where Britain’s most dangerous cons.

Glamorous-sounding, but not true. The dangerous ones were mostly hanged. We mostly got petty larcenists, usually desperately poor.

 

[cuervo]

Glamorous-sounding, but not true. The dangerous ones were mostly hanged. We mostly got petty larcenists, usually desperately poor.

If it is "glamorous-sounding" then it must mean that I write it right

No, I'm not a Mexican bandit, but I don’t like the stereotype as my fellows Aussies should not like the ex-con image, and I must say that I think Australia it's a marvelous land with excellent people.

 

[cuervo]

Crikey!! A real Mexican Bandit

Nice picture, I think they are revolutionary soldiers (1910-1917), not bandits, but it's a nice historic Mexican picture anyways, cool

 

[cuervo]

Back to the subject, sorry for the deviation.

I'm drooolong for a set of Easton EC-90 Carbon wheels, I think they substitute the Tempest II model.

Seems like the are light, stiff, strong and aero, what else can I ask for? maybe the they do not cost $2,000.00 ...