I'm very anti-fitter when it comes to TT position as changes in CdA can't be taken into account without testing.
That's just not true.
Oh? Go on, enlighten me.
I would take less issue with the statement if you replace "taken into account" with "measured precisely". Is that enlightening? I still disagree with the first part, but also understand that most riders' experience with bike fitters is less than ideal. I wouldn't quite say the industry is in shambles, but it is pretty much the wild west out there, despite our editor's attempts to improve it.
"Taken into account" really just means thought about or considered, and I consider the aerodynamic effects during every bike fit. Are my assumptions always correct? Probably not. Is lower always faster? No. The thing is, "lower isn't always faster" is just a trite way of saying that it is almost always is.
Certainly for the 99% of aerobar riders who walk through my door with 110Â° of hip angle and their heads 9 inches over the level of their back, yes they are absolutely leaving with improved, yet unquantified, CdA. For the 1%er, the slowtwitch reader, most likely you, there is less certainty, and I wouldn't propose to be certain. What I would propose is that the modern fit bike in capable hands is the place to begin. My goal for such fits is to insure the primary coordinates are optimized and then a formulate a hierarchy of questions to be answered via field or tunnel testing. Those questions are almost always 1) what helmet should I wear? 2) what clothing should I wear? 3) should I angle my forearms? 4) should I ride narrower or wider? 5) where should I put my nutrition?
Conspicuously absent from that list is "How much drop should I ride?" While that is a question that testing is entirely qualified to answer, it's just not the low hanging fruit of testing time. There are just so many variables going into front end shape when you consider drop, reach, elbow width, hand width, aerobar angle, aerobar cant... and then how they all play into different helmets... testing everything from scratch is not possible. You have to start with a proper fit on proper equipment, with certain aerodynamic assumptions, and with an experienced eyeball wind tunnel that "takes into account" the most likely effects on CdA.
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