I put this in the Bike Fitting Forum but no response, thought ths forum might be better.

In the 80's we used for the starting point to check your reach on a road bike to look down at the handlebar and see it the wheel hub was obscured. If it was then you had a good reach to start with. We had a discussion about this at our bike shop and we can't remember whether this was done when down in the drops or not. Does anyone remember ?

I don't but I use that approach for the position on the bar where my hands are the most. There isn't really much variation if you do it from the hoods or the approach to the hoods.
Recommend Dave Moulton's Blog - Dave Moulton's Bike Blog (squarespace.com) Look up fit on the archive list.

I think we used to do it on the hoods as that is sort of a halfway position

Hoods

What happens when the front center of the bike is different?
you grow or shrink?
this was an old bike shop mechanic tale when distances between the front axle and bottom bracket center was typically 59-60 cm
Even then only a "ballpark" guide
and major league ballparks vary quite a bit.

Placing the back of the bent elbow against the leading edge of the saddle, your extended finger tip should touch the back of the bars.

I have a distinct memory that the hub should be obscured when in the drops. I don't remember where I read it, though Dave Moulton refers to it in his stem length blog entry (but I got a right-sized bike in 1981, long before there were 'blogs).

I've also used the forearm+fingers/ saddle nose-h'bar method. I once bought a bike that matched the forearm+fingers rule of thumb; I felt cramped and didn't ride much until I got a bigger bike. Before I used a trainer, I felt excessively stretched using the obscure-hub 'rule' for the first 200 miles every season.

I checked my 3 available references (DeLong, Sloane, and The Custom Bicycle), and they give 3 different methods for setting reach.

I think there are numerous 'rules' for reach because a relatively high number of variables go into it and because the choice really comes down to personal preferences. BTW, my feet and forearms don't have the same length; I may be an outlier, or DM may have used a skewed sample.)

Last thing I adjust is the stem length. Saddle first. Start witht he hub hidden because every bike I have ridden is most comfortable with that reference.

I always understood that it was determined when in the drops.

Whichever position you find yourself using most often.

You install a longer or shorter extension stem.

you missed or ignored my comment.
all else being equal, the concept of having the bars obscure the front axle is just near meaningless, bike to bike.
the individual does not change, the bikes are different.

Back in the 70's on Vintage Road Bikes it was with hands on the Hoods, but not so with Vintage Track Bikes. I have only been on a Track Bike twice and I remember the Hub well in front of the Stem...

I am not sure if any of this applies with today's configurations of shorter wheel bases and aero bars... Good Thread...

[laughs in Cannondale criterium]

Hoods is what I heard years ago, but it's all over the place with stems and handlebars and brake/shift lever hoods of different reaches.

I confess that fifty years ago I believed the hidden hub rule and the saddle-nose-to-handlebar fingertip rule until I discovered that, for my anatomy, on my bicycle, it was impossible to find a comfortable position that reconciled the two.

How upright do you sit? How long are your arms? How long is your torso? How long are your femurs? What is the rake on your fork? What is the head angle? How much bottom bracket drop?

These old rules of thumb came about because they seemed to work for many people, but there are many exceptions to these rules.

Brent

I always heard this one as: The back the bent elbow against the leading edge of the saddle + the width of your hand from the extended fingertip = the middle of the bar tops.

Using this formula results is a comfortable position and also checks the box of “obscuring the front hub from the drops".

Disclaimer: I’m tall, all torso and arms

Hoods

If I’m done building up the bike it’s applied when I’m in the drops and if it doesn’t look right then I try it when I’m on the hoods. Whatever it takes so I don’t have to change out the stem again.

Why can't I turn off the part of my brain that wants to turn this into a double entendre?

The bar obscure hub method or the elbow to finger tip method both will get you into the ballpark. Neither method takes into account the vast differences in handlebar reach and drop. Brifters also add another layer of complexity as they tend to extend farther than old school brake levers. That can account for 3 to 4cm variable even before thinking about stem length. Miles on the bike is the best method for finding what is correct extension that fits you.

The bar obscure hub method or the elbow to finger tip method both will get you into the ballpark. Neither method takes into account the vast differences in handlebar reach and drop. Brifters also add another layer of complexity as they tend to extend farther than old school brake levers. That can account for 3 to 4cm variable even before thinking about stem length. Miles on the bike is the best method for finding what is correct extension that fits you.

I never really checked. I just checked a couple of my favorite bikes and the reach seems to be a bit long by the "elbow to finger tip method. I have a short torso but very long legs and my bikes (the larger ones) feel comfy the way they are. I will try shortening the distance up a bit by moving the saddle forward , easy enough to move back if it doesn't make the bike more comfy. I find it interesting that all my bikes (again the large ones) are very close to the same! The exception is the shorter 60cm bikes I have. The shorter bikes are definitely not as comfortable as the taller , 62-64cm bikes.

Don't worry about it. You possess the rare quality of being able to grow up...but not growing old.

Sincerely: a "Xennial"/"Oregon Trail" person

Relevant to the topic:
I do the elbow/handlebar overlap from the tops of the bars. I would fit people so that they could have more or less a 45 degree position when at the tops, and it'd give them more or less a 35 degree at the hoods or the drops.

That being said: my customers were mostly people using old 10-speeds for city-bicycles. I was fitting them so that they'd be able to sit up and see traffic comfortably.

I am of the opinion that to determine your position, you need really to be on a trainer or rollers, and someone off to the side a ways back need to image you. Focusing on where you have your hands most often. a video from behind is useful also.
This lets one review pedaling, that should be set first.
No scooting the saddle forward or aft to get "reach"
with the saddle set, then go after reach.
Out on the road I see so many guys with the saddle too high, pelvis rocking side to side.
Knees swinging in and out (poor cleat adjustment)
Elbows locked. a set up where one has a slight bend in the elbow helps absorb road shock.
Attend to to those factors, including the subjective, does this position look comfortable?
your sight line to the front axle will take care of itself.

Some of this will be set by the choices of the builder, the seat tube angle or "setback" can have you matching or fighting what the builder made.

Rotate your hips...forward or back...reach changes drastically and that front hub goes from in front of bars to behind the bars.

Elbow to fingertips was the way. But now, all my bikes are that plus 4-5 cm.