By the way, this then begs the question...If creating turbulence is a good thing, and texture creates turbulence, don't wrinkles simply create turbulence too? Why are they bad, but texture is not? :-)

I'm going to "attempt" to keep this short - we'll see if I succeed. Just know this explanation will be simplified a great deal.

Just to be clear on nomenclature: the pattern is the actual cut, or shape of the panels, on an article of clothing. Where the panels are placed can have a large impact on how a piece of clothing fits and feels, and the fit, as discussed, will have an effect on air flow around the clothing. Texture is how a piece of fabric is woven, and a particular piece of fabric's texture can be altered depending on the weave pattern. Texture can also be added by a process known as flocking. Material texture can also have a significant impact on air flow around an article of clothing.

Typically, utilizing textured material in a performance piece of clothing like a tri suit is an attempt to create air turbulence. This might seem counter-intuitive, as turbulent air causes more drag over a surface than a nice, laminar, flow, but really what the manufacturer is doing is choosing between the lesser of two evils. Between the two types of drag: friction and pressure, pressure drag is by far the worst. When air separates from an object, pressure drag is created. However, if you can delay the separation of the air from an object, pressure drag is reduced and that object moves through the air more freely. As it turns out, turbulent air, while causing more friction drag, delays the separation of air from an object and, therefore, reduces the amount of pressure drag. This is commonly known as "tripping the boundary layer" and is best illustrated by the dimples on a golf ball.

If you're still with me on this, let me add to the equation that an article of clothing's pattern can also act as a Boundary Layer Trip, mostly due to the placement of seams connecting the patterns which form the piece of clothing.

The question some are trying to solve is: What is the best combination of pattern and textured material for delaying separation of air from an article of clothing on an athlete's body? Answer this, and you'll have a fast piece of clothing. Castelli is pretty darn good at it, and the placement of seams and specific textured materials on the T1 in specific places is their attempt to reduce pressure drag while allowing for a piece that fits properly with adequate comfort and range of motion (the fit being very important).

Hopefully that all makes sense. It's probably an article I should just write to provide a better explanation, but time always seems so short.

By the way, this then begs the question...If creating turbulence is a good thing, and texture creates turbulence, don't wrinkles simply create turbulence too? Why are they bad, but texture is not? :-)

is what we're saying here actually that the chance of getting it right is so small, that you're almost certainly going to be going slower with a mass produced sleeved tri-suit over sticking with a sleeveless tri-suit and bare skin?

sounds like the variables on the age of material, how wet it is after the swim (or if raining), how wet it is from sweating (fabrics perform differently when moist/ wet), wrinkles, seams, pattern/ direction of thread on the material, wind direction, wind angle, humidity, whether the wind has been disrupted blowing through a hedgerow, whether it's smooth air, how the aerodynamics of the suit are interacting with the aerodynamics of the bike, body shape of the rider.... need to be so specifically fine tuned that you're unlikely to actually realise the potential theoretical aero advantage that is possible in controlled testing? especially that most of these variables will change over and over during a race.

i think most of these also apply to most aero 'gains' you can get from equipment. if you actually added up all the extra benefit you were supposed have gotten from all these aero parts you should have theoretically taken off a hugely unrealistic amount of time from your tt times.

the reality is that it's not possible for something to work in all the conditions that come up during a race, interact with all the other complex aerodynamics of other parts and work for every different body type.

after a reasonable baseline of aerodynamics everything else must surely be either not working as intended and at best having zero benefit or worse slowing you down.

still didn't stop me buying those lovely firecrests this year though......

Funny you mention Champ Sys.....