Originally Posted by
Kontact
I don't know that the OP's Planet X bike is carbon. Here's one with an external headset:

Ah, the gravel bike. X-large has a 59 cm virtual top tube, but a 165 mm head tube. I looked it up on the Planet X web site. I'll bet he bought an x-large Pro Carbon, 58.5 top tube and 19.0 head tube.