Regarding the Tarmac SL8 for 181 cm, I’d say a 56 cm is generally the right size. It tends to offer a good balance of comfort and performance. Of course, your exact sizing might depend on your body proportions like inseam and torso length, and your preferred riding style. If you want a more aggressive and stretched-out position, 56 is solid; if you prefer something more compact, a 54 could work with some stem and handlebar adjustments.
What frame size do you normally ride? And do you know your inseam or saddle height? That info can help fine-tune the recommendation even more.
Hope this helps! Let me know if you want to discuss more.
Want me to tweak the tone or shorten it?
Thank you for comprehensive comment! My inseam is 86cm, and saddle height 74cm measured along seat tube. I have done bit of DIY bike fit based on Neil Stanbury videos. I feel I get the cleats and saddle height / position quite good, but cockpit area still needs some work.
Played also with Specialized sizing tool which is based on height and chin length, with their guide I measured approx 40cm chin length. Interestingly, I got 56 when entered 181cm and 40cm, but 54 when entering 181cm and 39,95cm... Seems I am just between sizes according to Spez as well.
Currently riding Kona gravel bike with size 54. Comparing with geometrygeeks I see there is not much difference in reach - 54 is 4mm shorter, and 56 is 7mm longer. Stack on the other hand is 25mm lower on 56 and 46mm lower on 54. But as I don't have earlier experience on real road bike, I am not sure how to read this. I have swapped to longer stem and removing spacers, and feel I can definitely go lower. But how much, that I don't know.
Interesting comments from others as well. I keep seeing "size down" for this bike. Could you guys share reasoning why this recommendation?
Regarding colors, I got YS color options which is listing many metallic and pearl color options. I am sure I can pick nice color form here!