I'm 182cm. I currently have an ICAN A22 (54cm) that I find too aggresive. I had a fit done and was told everything looks good, but I could maybe use a 5mm stem spacer. I'm never really that comfortable on it and my lower back bothers me. I find I'm always on the very back of the handle bars, it feels too long and low.
Can you say more about the lower back pain? Is it something that comes with time on the bike or is it something that shows up in the first 10-20min of riding? What is your handlebar configuration right now?
I am a little surprised by your fitter being OK with your fit, I am guessing your bike is simply too small. Trek would start you on a 58cm on their Emonda and probably size you down to a 56 if you wanted a "race" fit. The A22 is the same length as the 58cm Emonda but 27mm lower.
I was thinking about find a more enduro like frame and have been looking at the Elves Eglath (53cm). This will approximately raise the handle bars about 20mm and the ETT is also ~20mm shorter. Would this be considered a significant change in geometry, or would it be barely noticable? Thanks for any input.
This would be pretty significant change in fit. For most people its a bigger change than their race vs. endurance / gravel fit.
I am seeing a 10mm increase to stack and a 15mm reduction in reach with the Elves frame. However the seat tube angle is steeper which is why you lose the additional 5mm on TT length. This might end up being a problem as it would be close to 8mm of additional setback you would likely need at the seat clamp. Elves doesnt list a setback on their site, so I am not sure you would be able to get the right saddle position. You might want to consider sizing up on the Elves but then stack then might be too high.
If you can, the easy thing would be to raise the bars on your existing by 20mm or so and see if the pain goes away. If you can flip the stem that might be worth trying. If you cant and you have a trainer I suggest cutting some foam and taping it to the ramps of your bars to simulate a higher hand height and seeing if that helps. Adding padding to the ramps is a pretty good way to see if you will be comfortable on the hoods if you were to add in spacers to reduce the height given a similar frame reach. My guess would be that you should try raising the bars before going for a shorter fit.