There Are Two Ways to Set Up a Road Bike to Ride Low and Fast: Stacked High or Stretched Out (and How to Choose Wisely)
Let’s talk road bikes, speed and comfort, because what a fun, wonderful topic that is!
The industry has been stuck on the position that “most people want to ride in a less aggressive posture for comfort” for some time. I’ll admit, riding a little more upright on my gravel rig isn’t all that bad, but neither is low and sleek on my Venge. I’ll tell you what is uncomfortable; trying to ride with our A or B group whilst imitating a sail atop your bicycle on Tuesday night! Actually, riding without a motor is uncomfortable with the A group now that I think about it. I digress.
For those of us who are burdened with the need for speed, and lots of it, that upright posture requires more watts than most will be willing or able to create at 25 to 28-mph. Even in a draft. See, approaching 30-mph, pushing air out of the way is not easy. With a draft and, say, a foot between wheels, if you fit in the slipstream it takes considerably less effort to keep the bike up to speed. If, however, your head is always sticking up out of that slipstream, your benefit won’t be near as spectacular. I’ve actually done experiments north of 30-mph in the past, just to see what it was like. If you’re head’s above the draft, the difference is surprisingly great.
The photo above illustrates the point well. I’m the guy on the left, my riding buddy, Chuck is on the right. He’s down in the drops while I’m on the hoods and our heads are about the same level. We’re both the same height as well. If I’d been sitting up higher, the ride is still easier than no draft, but you can feel the drag when your head is above the draft – which means you’ve gotta get that melon down in it!
Now, there are two ways to handle getting your head down into the draft. First is simple: buy a small bike, put a long stem on it and peg the saddle just as high as you can get it so you have a massive drop from the nose of the saddle to the handlebar. I cannot ride like this so I’ve got a photo from a post way back I can use:

That’s A LOT of drop right there. The problem some of us older farts run into is that we simply can’t crane our neck enough to see down the road with the saddle to bar drop steep. Believe me, I’ve tried. I can’t do it without turning my head sideways and taking glances up the road. I only lasted ten miles before turning around and heading home.
I have to opt for the second option and stretch out a little bit. I have a larger bike (the proper size for my 6′ height, a 58 cm frame), and use a long cockpit to get low (note how much higher the drop bar ends are on my steerer tube):

Also, and interestingly, the setup above, at least the saddle height with the amount of seatpost showing above the frame, is technically “correct” for a standard frame. The stem choice, a flipped 17 degree 90 mm stem, was “after fitting”. I had a 12 degree 80 on there prior but a shorter reach drop bar by 10 mm meant a longer stem was needed and I wanted that sleek look I got with the steeper stem. That Trek evolved to that setup over twelve years. The bike I originally bought isn’t even recognizable contrasted against what it is today.
My really, really good bike employs almost exactly the same setup:

While there’s plenty of drop from the saddle to the handlebar, the Venge is almost the same as the Trek – it just looks like more drop because the top tube of the Venge slopes down.
I chose reach over a massive drop (technically, a decent mix of both drop and reach, but lets stay on point) to get me low because of the aforementioned neck issue and because I’m a little chubbier than I should be. This is, of course, in cycling terms. I am not, in any way, shape or form, “chubby”. I’m what you’d call “cycling chubby”. The point is, you can’t cycle around your gut if your quads keep bumping into it. Therefore, a little bit of stretch will help you get around an extra slice of pizza.
Stretch has its problems as well, though and they can be just as bad as too much drop in the saddle to bar top. Too much stretch too soon will have you sitting up with your hands on the bar top rather than around the hoods where the hands belong. The drops will be virtually unusable because if reaching for the hoods is uncomfortable, reaching a bit further for the drop will be even worse. Therefore, stem length and saddle setback have to be carefully considered in terms of reach and stretch. This doesn’t mean we should live with an upright cycling position, just that we should be careful not to alter that setup with big changes and short break-in periods.
This gets important when we consider the one thing that a lot of cycling will do for a body: make it drop weight. As we ride more (and hopefully we don’t eat more to compensate), the body will change. With enough speed and mileage, weight can melt away. That’s the way it happened with me, until I changed my eating habits, at my wife’s urging, before I turned into the human equivalent of a twig. As the gut disappears, we can lower/stretch the cockpit so that we can ride lower which will make us, naturally, faster still.
The key here is to change the setup on your bike a little bit at a time with a break-in period between changes so you can evaluate how each change feels. This way, if you run into something you don’t like, you can change it back and go another route before you get lost.
Above fast is always “fun”. If you aren’t having fun, you need a reevaluation, because everything about riding a bicycle should be fun… unless someone is paying you to ride one. In order to have fun, you have to be comfortable atop that steed. The key is you get to determine what is or isn’t comfortable, not the industry.