Our new tandem has carbon fiber drop handlebars.

It seems like the length of the bar ends is shorter than I like. When I get down on the drops (not all the way forward in the curved section) my hands are at the very ends of the bars.

I've looked at specs for various bars and I don't know what defines this dimension. I don't think that it is "drop" or "reach".

Any idea what defines this dimension? Are there bars where this section is longer?

Thanks in advance.

The newer shaped bars seem to suffer from that issue. I have big skinny hands and run into that problem.

So my advice other than testing a bunch. Is to stay away from ergo bars and those with less drop. Stick with classic round bars.

In some cases the manufacturer has a dimensional drawing of the bars, if not you could ask for one.
I use FSA Wingpro (now called Energy) compact bars and find that is not a problem.

I use the same bars actually. I don't know what that bottom dimension is called either. AFAIK the only way to have more of the bottom (drop) portion directly under you is to rotate the bars forward. Current popular practice is to rotate the bars backward so the ramp to the brake hoods is as level as possible. I have mine rotated a bit more forward so there is more 'drop'. I don't know of any bar that allows you to have it both ways.

I can see that. I spend most of my time on the top of the brake hoods. It seems most comfortable when I have the bars rotated "up". However, that causes the compromise that when I am in the drops, there isn't much bar to grab onto and reaching for the shifters is a long reach.

Other questions: 1) When the width of the bars is listed (e.g. 44cm), is this usually outside - outside or center - center? 2) When they list drop & reach, how is this measured?

Do people have preferred brands or models? I think that I would like to stick with carbon fiber.

Our current bars are very ovalized just outboard of the stem clamp. I assume this is to spread out the load on one's hands. However, I spend very little time in this position so this feature isn't important to me.

I can see that. I spend most of my time on the top of the brake hoods. It seems most comfortable when I have the bars rotated "up". However, that causes the compromise that when I am in the drops, there isn't much bar to grab onto and reaching for the shifters is a long reach.

Bar end shifters? Mind if we ask about your bike? What make, sizet, etc. And you (height, etc.)?

Other questions: 1) When the width of the bars is listed (e.g. 44cm), is this usually outside - outside or center - center? 2) When they list drop & reach, how is this measured?

Center - center. Just about everything on a bike is measured center to center, unless specified otherwise.

Do people have preferred brands or models? I think that I would like to stick with carbon fiber.

I recommend you stick with the bars you have unless you need to change a vital dimension like 'reach'. There are only three kinds of bars: classic, ergo and compact. All of them have the end of the bar level with the heel of the bar at the top. If you want the end of the bar to project beyond the heel of the bar like in my photo you have to rotate the bar. Good carbon bars are not cheap, cheap carbon bars are not cheap. My bars are not carbon. But the compact bend is becoming nearly universal.

Our current bars are very ovalized just outboard of the stem clamp. I assume this is to spread out the load on one's hands. However, I spend very little time in this position so this feature isn't important to me.

Those are called "wing" models and the shape is supposed to help you when climbing.

Here. More than you wanted to know about handlebars: Tech: How to Choose the Correct Road Bike Handlebar Size & Shape - Bikerumor

Thanks for the Bikerumor link. This is very informative.

As far as our bike goes, it was a big upgrade from our 20 year old Co-Motion. We went with a Calfee Tetra with Ultegra Di2. Our old steel Co-Motion had bar-end shifters. I liked the bar end shifters pretty well. The Di2 shifts very well but I'm still having some issues getting used to it. If I am in the drops, it seems like a long reach to get to the shifters.

I don't have the bike here & I forget what bars are on it. The bike was assembled by a bike shop far away so I can't take it to them for custom fitting.

When I remember, I will take a photo of the bars & how they are set up.

The FSA Wingpro bars I use are aluminum and are ovalized at the tops. I find this to be more comfortable than a round bar. I don't feel a need to use carbon bars but would not hesitate to use them. Measurements on these bars are a little tricky since they flare out at the ends. So they are wider at the ends than where the shift levers are mounted.
Normally I use a 40cm bar but for these I use 42cm. Some bars are measured C-C and some are measured outside to outside.

You can get DI2 satellite shifters and mount them anywhere you want on the bars.

The shifters are potentially mounted too high on the bars, causing the levers to flare away from the drops. For example, the Raliegh pictured above has that problem. Try shifting the levers down ~5mm. The bars are basically designed to have the ramps go horizontally to the levers.

I've got the same FSA bars on my road bike, and find them great. The thing is these bars are basically designed for a modern pro setup. What that means is that the vast majority of your riding is done on the hoods, and the drops are used basically only for descending. That means that you generally want the hood position more aggressive than for a classic style bar where you ride mostly in the drops. The short reach/shallow drop combination means that there isn't as large a shift in riding position from tops to hoods to drops.

We're using 3T Ergonova bars on the front of our tandems and all our singles. It think its a similar shape to Zipp's SL70 with 70mm of reach. The FSA has 80mm of reach. It would be the most common bar for Steve Hogg to put people on when their bars don't fit.
Just making the clydesdale category I use the aluminium bars. Riders who are more svelte than I would be fine on the Team carbon bars which Marian uses.
The LTD bars are for the "discerning individual" or weightweenies

If you are using modern equipment and have the tops of your hoods pretty much even with your ramps and the brake levers approximately vertical, your bars and levers are probably arranged as they were designed to be. I find that ergo bars make it easier to reach my levers than do round hooks. I normally ride either tops, hoods, or on the ergo portion of the drops. I never ride on the straight part of the bars which extends aft of the ergo section. When going hard, I'm more likely to be on the hoods with a lot of elbow bend than to be in the drops. When I sprint out of the saddle or descend at speed, my back is flat, my hands deep in the drops with a couple fingers on the levers. That's what modern components are designed to do.

In old photos you see racers spending much of their time in the drops. When I was 17, 54 years ago, that's what I did too. For one thing, the hoods in those days were torture devices and not meant to be used the way they are today. For another, back in the day bar tops were approximately even with the saddle. Now bar tops are usually inches below the saddle and hoods position is about the same as drops position was back in the day. Back in the day, the drops aft of the hoods was usually level. Today that portion of the bars points approximately at the rear axle of a single, or where that would be on a tandem.

Photos: Lovely Bicycle!: Drop Bar Hand Positions: an Introduction
I prefer the hoods mounted a tiny bit lower than shown so that the brake levers are vertical. This would make them easier to reach. The photos also do not show what I call the "low hoods position" with the elbows well bent, the thumb on top of the hoods, and the wrists resting on the ramps.

Thanks for the link on description of hand positions.

Another question: Is there an illustration of ergo, compact and other variations of drop bar shapes?

Just google Images for "bicycle ergo bars", etc.