frizank

This thread has been inactive for a while but thought it worth mentioning. I recently picked up a 2020 Gan and had the same question because I couldn't find it anywhere as I had lost my sales receipt. I went in for a fit today at the same place I bought it and asked the question and someone there pointed out that the frame size can be found in 2 (maybe 3) places: On the box it's shipped in and embedded within the bike's serial number. I'm too new to post pics here but my serial (beneath the bottom bracket) is 8CT5150870091.The frame size is in bold. My frame size is 51.5" according to this and I had them look up my sales receipt (which would be the 3rd place depending on the shop) for me and sure enough it matched.

Hope this helps!