[Closed] short gf getting neckache on longer rides - any tips etc

Hi

at 4ft 10 she's on a 13" Spec Myka, which works well but she is getting neck ache on longer rides, I've improved her rucksack (Evoc, proper padding and waist chest straps), and am now wondering about a shorter more upright stem.

Current stem is 60 os, so I guess 40 os is best I can do but was wondering about the adjustable ones, in a nearly straight up position(*she's a very gentle rider) so I could raise the bar height a bit.

Any other thoughts/ suggestions - thanks