Well, I’m the same height as her (shorter legs though) and always a medium in Spesh bikes. The medium Myka is the same size (Seat tube) as a meduim FSR, just 35mm shorter
The medium size given equates to 17.8in (Seat tube) and Mrs PP has a 17in Hardrock as a commuter which fits her well.
I’m erring towards the medium…..
BUT she currently has a 17in Kona King Kikapu (mens frame) which looks a tad small on her in the leg, but too long
The large Myka is 10mm LONGER than a mens medium….
So I’m unsure!!
Arghhhh!
EDIT
She needs something a bit taller, but shorter than the kona
**heads off to find Kona geometry**