aquiver

Hello,
wondering if I should get a 56 or 54 cm specialized diverge. Can't test ride in my lbs right now, as due to covid they don't allow test-rides.
My height is 5'9.5
Inseam is 30.5
Armspan is 64.5 inches
I have short legs, short arms, and a long torso.

Any advice on sizing would be excellent.

CyFan4036

With a long torso I'd recommend a 56cm but there are so many variables that are unknown. I have a 31" inseam and a longer torso and arms and a 56 fits me perfectly. But mine is a Cannondale. I have 1" of clearance from my top tube and it feels comfortable to ride.

Troul 

I'd go with the smaller size.

nomadmax 

You can make a small bike bigger but you can't make a big bike smaller. If it were me, I'd get the 54 and run a longer stem and get a tighter triangle/better standover in the deal.

GeneO 

Smaller 54. Your proportions are pretty normal iME.

Outrider1

This. I'm 6 feet and ride a 56.

MattTheHat 

Yep, I’m 6’ and ride a 56 Diverge. 31” inseam. I run a 90mm stem. I’d vote 54.

sledgefisher

I am 5'8.5 and have a 56cm bike that is just a little too big for me and although I can ride it, it never gets used. Go 54cm and use the bike more.

blakcloud

Sorry to be the naysayer here but go to the Specialized site and fit generator and it will come up with 56 which is what I would put you on. When I hear 6' foot people on 56 I have to ask who do they make the 62 cm bikes for, 8' tall people?

Ironfish653

Depends. You could probably ride either, depending on what you’re looking for. I am almost exactly the same height and inseam as the OP, and while I fit fine on a 54, I found it very short front-to-back, and surprisingly upright, more so than my XC bike. The 56 was better, although still higher than I was expecting.
The Diverge just wasn’t the bike I was looking for, I ended up on a 56cm Cannondale Synapse.

Wilmingtech

I'm 5'10" with a 31" inseam. 54" is the way to go here. You will have much more room to adjust in stem length, crank size and seat post height on a 54 than on a 56. You can get a 56 to work but the 54 will be lighter and have more adjustment.

bruce19

In my youth I was 5' 10 1/2" with a 32.5" inseam. Down to 5' 9" but same inseam. I find a 54-55 is perfect. If my inseam was like yours I'd go no larger than a 54 and probably a 53. Be careful when buying a bike with a sloping TT. My CAAD 12 is a 53 but using virtual TT measurement it is actually a 55.

MattTheHat 

I just did that. At 5’9” it comes back with 54. If you enter 5’10” it comes back 56. The OP should probably use their size calculator and enter the other measurements they ask for, not just height. I’d be curious to see which they recommend.

Paul Barnard

It is likely that both bikes can be adjusted to fit you just fine.

aquiver

They actually recommended 52cm.
Measurements for knee to floor was 18 inches and ankle to floor was 3 inches.
I also measured some more and inputted information into competitvecyclist calculator although i'm not sure I measured everything correctly, and it gave me these frame specs:
https://imgur.com/tG1OcY0

Atlas Shrugged

There is a tendency to ride smaller bikes as that's what the current pros ride. In days past seat posts only came in 180 cm lengths and road stems were horizontal to the ground. The typical MAMIL setup is a bike with a tall stack of spacers and a sharply angled stem rather than just buying a bike that is one size larger allowing a more stable ride and comfortable fit.

MattTheHat 

Okay, interesting.

trailangel

Short legs, long torso, size up to the 56 for the longer reach.
52....? don't be ridiculous

Hornplayer

I am almost exactly your dimensions and am very comfortable on the 54. These bikes have very relaxed geometries and while there has been a lot of discussion of reach I would be concerned that on the 56 the stack would be too high and put you overly upright. The Future Shock is not a pile of spacers that allow you to lower the stem. My recommendation is go with the 54 and change to a longer stem if you think you need it.

phughes

I'm not sure where they are getting that, but you could actually use either. If you want your bars up higher, you may want to go with the 56. Both will work, both may need some adjustment. No big deal either way. When I got my Surly, I could have either used the 54 or 56. I went with the 56. I have less seat post showing than most, but I don't have to run a ridiculously high stack of spacers under the stem. I like the slightly longer wheelbase as well, the bike is extremely stable. Whichever way you go, see if you can get it with an uncut steerer. That way you can ride it a while and see where you want the bars, before cutting. I know you can get the Surly with an uncut steerer, but I had to tell the shop that is what I wanted.

Here is Specialized chart for the bike you are considering. You are on the cusp between 54 and 56.

Cyclist0108

Based on this, I would go for the 54.

I have very similar measurements (including armspan -- I just checked). I got a custom frame built, and it turned out to be almost identical to a 54cm Trek Domane. I know that isn't one you are looking at, but it might be a useful starting point.

This link, if it works correctly, should compare a 54cm Domane to the two sizes of Diverge you are considering:

https://geometrygeeks.bike/compare/t...arbon-2020-56/

I think you will find the reach too long with the 56, and the standover height too high.

Random11

I am 6 feet tall and ride a 58cm Diverge. It's a great fit and very comfortable. Based on that, I'd think the 56 would be a better fit for you. But I'd also be reluctant to buy without trying it out first.

Whitrig

I’m the same height and inside leg and I’m very happy with the 56 frame on my 2018 Diverge.

bruce19

Inseam not height is a better metric for proper fit.

bruce19

Back in the day...the pros rode the smallest frame that work because they were lighter.