I'm 5'11, 32.5 inseam when bare feet. However my wingspan is only 5'8 or 68 inches.

The 56 fits a tad long in the reach, perhaps I could get 90 mm stem and that could work, or should I get a 54?
The 56 I tried had a 100mm stem and 80mm reach in the handlebars.

This is not a question anyone can answer for you.

It's hard to analyze your fit from the information provided, but using myself as a reference your inseam is 2 inches (5 cm) shorter than mine. Over MANY years and several bikes, 59 is my frame size. With your inseam 5 cm shorter, 54 sounds like the answer, particularly with your relatively short arms. A lot can be corrected with stem length, which is available in small increments and relatively low cost.

Realize that a smaller frame size of the same model will also have a lower stack height. So that closer bar will also be lower. And new bikes come with the bars as high as they can go. Without making them fugly with other added stuff. And used bikes might have the bars slammed and the steerer tube cut. So also requiring more stuff to get the bars higher.

Ride the bikes for as long as you can and then make a decision which you like. If you buy one and then find out you don't like it, then maybe you should have gotten the other. And will better know for your next bike purchase.

Being stretched out on a bike isn't necessarily a bad thing. You'll be more aero than with the bars closer to you and your arms straight. So that'll save you watts. Or you can save watts by having the bars close with a lot of bend in your elbows. Either will also help keep you from getting numb wrist and hands. Assuming you also can hold the hoods and bar correctly.

I was in a similar situation when I picked up my Checkpoint in '19. At 5'10" I typically ride a 54 but the CP is a 56. I felt just a tiny bit stretched out so I swapped the stem from 100 to a 90, and I've had zero fitment issues since. Of course, YMMV.

If buying new, take advantage of Trek's 30-day trial period. Just don't scratch or break the bike during that time.

The Trek fit guide for the Domane puts you on a 56. I'm 5'9" with an 83 cm inseam, I am very happy on a Emonda 56 with a 90 stem.

Domane endurance road bikes – Trek Bikes

Perhaps you should go for a bike fit session first...it will answer all of your questions...

Trek Checkpoint sizing gen 3

yea I know, it’s just fitter costs 400 bucks here

So like 3 dozen eggs? Seems worth it. How much does buying the wrong size bike cost? Why not just go to a Trek dealer and take it from there. I agree with the poster above, that the stack is going to be the isue, and these days it's becoming more of a pain making changes to the front of the cockpit.

This is ultimately the answer. But, if it adds to the discussion, At my full height I was 5'10 1/2" with a 32.5" inseam and a 54 w/ 100 mm stem fit me very well.Bear in mind my frames have been measured traditionally and not based on what a manufacturer claims.

So you'd rather spend several thousand dollars on a bike (or two) and take the advice of internet folks who have never seen you and know next to nothing about you, your riding style, etc.? If you are willing to spend that kind of dough on bikes, the cost of a fit session seems minimal. Consider the cost of a proper fit as an investment, not an expense. Riding a properly fitted bike is a wonderful experience.

I'd have to believe Trek shops - whose bikes you seem to be focused on - offer fit sessions. Some fitters will give you a discount on a bike if you purchase it from them (don't know Trek shops offer this, you could always ask).

Good luck.

Not to repeat myself but….

If your Trek dealer can’t fit you on a bike you need to find a better dealer!

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This isn't an identical thread to what the OP recently started, but it likely couldn't be any more similar without being identical.

Thread moved from General to Fitting.

I'm 5'9" with a 29.5 inch inseam. I got a custom frame that wound up being nearly identical to a 54 Domane. You would need at least a 56; perhaps a 58. If reach is an issue, get a shorter stem. In any case, get fit to one at a shop that has no incentive to sell you a particular size.

I would go with the 54. I've heard it said that, if you feel that your bike is a bit too large, it's probably way too large. That, because your body is actually pretty adaptable to imperfect geometry. And it's generally easier to make a small bike fit larger than the reverse.

Your legs are on the stumpy side and Domane reach and stack are short and tall, respectively. Had I your build, though, I'd be more concerned about too much stack rather than too little reach. Get the 54 and a longer stem. Or consider a less extreme endurance bike.

when you say less extreme endurance bike, could you elaborate that in terms of stack and reach ?

A little more reach and and a little less stack. Perhaps a Giant Defy, Scott Addict (not the RC), or BMC Roadmachine. You'll have to study the geometry charts and do some test rides to figure it out for yourself. Are your arms long (proportional to your torso) or short (proportional to your legs)?