Help choosing the right size for gf...

[Kiwi Stoker]

If you are wanting to make a gift or surprise of it I suggest making her a handmade gift voucher from yourself saying something like "the bike of your choice".

Will save a lot of issues.

[Bethany1]

Nice bike! You're going to need to take her in for a fitting. If it's a surprise, make the trip a surprise, not the bike. Regardless, hope she loves it if you both decide to purchase it.

[Owlie]

If you are wanting to make a gift or surprise of it I suggest making her a handmade gift voucher from yourself saying something like "the bike of your choice".

Will save a lot of issues.

I like this!

What everyone else says. She needs a fitting. Height and inseam are only part of the equation.