Another (?) which-frame-size-to-choose post Unfortunately in my home country (a small tropical island) I can't find a reseller that has stock of an adventure bike (also known as gravel bike).  I am about to order one online, but I am stuck on the frame size. I would like your opinion on whether you would lean towards the smaller of the two or the bigger.  I have included a picture of the geometry of the bike, the sizing chart of the manufacturer (red line is my height) as well as my size (as measured with instructions from competitivecyclist[.com]).

I want to use it for commuting (on tarmac), weekend rides (80km at around 30-35km/h) as well as multi-day bike packing rides (unpaved roads).

Any feedback would be greatly appreciated!

Measurements    CM


Actual Inseam 87.5 
Trunk 59.5 
Forearm   34.5  
Arm   66.5  
Thigh 62.5  
Lower Leg 58  
Sternal Notch 151.5
Total Height  184






EDIT
Thanks CardMechanic (I am not yet allowed to comment on your answer below).  Would trying another bike (a road bike) really be representative for this particular bike I am considering?  The geometry would be quite different right?
From your description, you're a little taller than me with a little longer inseam and shorter torso.  I'm usually comfortable on both a 56 and a 58.  I fall somewhere between the sizes.  For gravel riding, I would probably err to the shorter bike just to have a little more control.  For pure road riding, I'd probably err to the taller one for better lumbar stretch(if you're in the more-flexible camp).  Fitting is such a personal thing, it's almost something best seen in person, or tried and felt.

Does the shop there have any road bikes in those sizes that you can test ride just to get a feel for it?