Did I move forward, back or sideways?
 

I completed my first (and only) century last fall and did it feeling great at the end. There is a rider in my group who does monthly doubles and has got me motivated to try one.
My bike for the century was a Soma Pescadero with 35 Bon Jon Pass tires, B17 saddle and front and rear saddle bags as i was carrying what I needed with me.
For the double I’m looking at switching to my mid 70’s Peugeot PX60 with 32 Gp5000’s and probably just a rear bag as my new route will allow me to resupply more frequently. As the Peugeot is lighter and feels quicker, I’m hoping it will result in a faster finish as doing 18? Hours in a saddle might be more than I’m capable of ( the trying is the fun part)
I have carbon bikes but while the road conditions on this route are good, I feel the extra impact of road cracks on carbon vs steel will hammer my elbows badly over the stretch of miles. Plus this Peugeot is a bit more upright which I will need long term. I’m quite certain I will only do one double in my life just to say I did it so want to increase my odds of success.

Am I moving in the right direction?

Seriously, that's your concern?

When I do really long rides, I have one consuming interest - to get my butt off the saddle as soon as possible. I ride a carbon bike, carry little with me, run a saddle that's comfortable for 18 hours, use as aero a posture as I can maintain for a long period, and only stop about every 50 miles.

If you think your carbon bike will hammer your elbows, your fit/position is not OK. I'd work on that first. It's probably the most important thing to focus on as you increase your mileage as it will increase your speed and endurance. In my mid-60s, my fastest double was 10 saddle hours, fastest 400k was 15 hours ET. I'm not a particularly fast rider, just well trained and using 20 y.o. good equipment.

A good goal for fitness is to be able to ride a century on any given day, no prep. A good way to get there is a consistent 150 miles/week or so, with one 60-75 mile ride/week ridden as hard as possible, with 3000'-5000' of gain.

You could try posting about fit over in the Fitting your Bike forum.

OTOH, many riders couldn't care less about their ET long as they finish within the time limit, if any. In which case, your equipment doesn't much matter.

With elbow injuries yes it is.

It's been a long time but I rode 25 miles short of that distance twice the summer of 1977. Solo, unsupported training rides. On the Fuji Pro I raced. Sewup training wheels and race gearing. The bike (and me on it) did just fine. I was in very good shape and that bike, in it's race setup, was home. (I hadn't heard the term double century yet. These weren't distance attempts. First was just a 150 miler crossing the ridge in southern New Hampshire. Got long when I got thoroughly lost on the MA/NH border. Got harder when I realized I was riding past Pack Monadnock, a small mountain I'd been looking at from the top of its sister for years. Just had to go up. Second was just a loop around the city of Worcester (starting in Cambridge), staying far enough out that I wouldn't see traffic.)

The PX10 should serve you well for this if setup/fit is good and the gearing appropriate.

I did a week long van supported trip with ACA three years ago, they hauled our camping gear in a trailer, all we had to carry each day was our lunch and water. I brought my folding bike for that trip, 40mm wide Schwalbe Marathon tires.

The rough chip seal in West Texas made for a really rough ride, my hands took a beating and my GPS started acting up from the vibration. Day one, I had between 55 and 60 psi in my front tire. Day two, dropped my front tire pressure to between 40 and 45. That was much better on my hands and my GPS was happier, rode the rest of the week at that pressure in the front tire. I was not noticeably slower at the lower pressure, the people that were behind me on day one were still behind me on later days. But, I was not riding for time, I probably was a bit slower. My rear tire was near 75 psi, but did not need to drop that pressure, only dropped the front pressure.

How much pressure do you need to avoid pinch flats on your front tire?

Side note: That GPS still acts up since that rough day, I think there was permanent damage from the rough chip seal.

Not sure how little pressure I can get by with to compromise my elbow injuries with an adequate rolling rate. With my new 32’s I’m guessing 65 up front and 75 in the back as these roads are not terrible but not fantastic either.
I’ve been doing a number of training rides just trying to evaluate such issues. At 60 years old this will be a bit of an effort so trying to maximize everything I can. Even if it’s only mental it can’t hurt.

Elbows are a weak point for me. I have worn braces, and also have to do pushups. I do pushups on the stairs so they aren't quite as stressful.
I don't remember why I stopped wearing the brace. Maybe because my elbows stopped hurting when I did the pushups.

I feel that just going a little more upright isn't going to help that much.

My elbows and shoulders are fine on shorter rides. It's when I start getting fatigued that I tend to lock my elbows, and then my shoulders and elbows start talking to me.

So my take is you might need to check your bike fit, but more likely you'll need to train (with whichever bike you choose) to be able to handle the longer distance.

Okay, but steel vs. carbon is not the solution to that problem.

I have knee problems, have had big toe problems, but never elbow problems so I can't suggest anything pertinent

My rando bike has 32mm tires. I usually ride at 60 psi front and 80 psi rear, I weigh about 185 pounds. In general terms I ride about 75 percent as much pressure in front as in rear, but as I noted on that West Texas trip i cut my front pressure to slightly more than 50 percent in front. But on that West Texas trip with my folder that had 40mm tires, I have never heard of pinch flats on a 40mm wide tire. With 32s, you are starting to get to a tire range where that could be a concern.

Good luck on your double century, I am 67 so I understand your concerns. One of my exercise rides last summer I bonked rather badly. After assessing everything I concluded I must have run low on electrolytes, now carry a bit of salty food in my handlebar bag that I can eat, that is in addition to the standard calorie sources.

Any of those bikes will be fine. Pick the one that's the most comfortable. My average speed on rides of that distance or longer isn't noticeably different on a 20 pound vs a 50 pound bike. How efficient you are at the stops will have a much bigger impact on your time than how heavy your bike is. I wouldn't sweat it either way since all you're trying to do is finish. Take your time and enjoy the ride on whatever bike you choose.

The difference between a 12 hour ride and an 16 hour ride is 4 hours at the end when you feel it the most,

so IMO you want the bike that allows the most aero profile without discomfort, and train to hold a good average speed.