I have currently a Kikr core with the zwift COG.
I would like to replicate the minimum gear ratio on Zwift to what I actually ride on (50-34 with a 11-34 cassette) especially on the minimum set up (34-34) to challenge myself on mythic climb. what should I use as the minimum virtual gear to have the same as I use to ride ?
See this article: ht tps://zwiftinsider.com/virtual-shifting/
34/34 = 1, which according to the table would be the default virtual gear #3. Your highest/hardest gear on actual bike is 50/11 = 4.5 which is shown as gear 21.
Note this only applies if you have your gear shifting mode in default sequential 24 gears, and not using the sometimes (based on installed equipment) emulated modes (such as for SRAM with 2 virtual chainrings plus a rear cassette).