scared I made a bad purchase for my girlfriend

[Cataboo]

17" for a mountain bike for a 5'7 inch person seems fine or a little big. I'm 5'1 & ride a 13-14" mountain bike, while a friend is 5'6 & rides a 15/16" mountain bike - they have a 33" inseam though. So in general, I'd say a 17" frame should be fine for her, but there's variations given specific geometry of that frame and your gf's specific measurements, which we don't know.

Anyways. For mountain biking, you want a smaller frame with more standover that you can kind of throw or haul around easily. You can fit a road bike frame much bigger.

You could have her professionally fit to the bike. is she complaining about anything on long rides? You can change the length of the stem to make the top tube longer (or at least the handlebars further away). You can change the handlebars and how much rise or sweep they have. You could put a setback seatpost on it as well. But before you do all that, I think you should find someone who knows about fit.

If you post pics of what your gf riding the bike, we can give you more comments... but once she starts doing longer rides, I'm sure she'll give you feedback on what hurts

[Irulan]

There are many variations in body proportion and fit. If the LBS isn't very useful, my suggestion is

1. understand what WSD is and is not. It is most definitely NOT for every woman out there, but for some women, of a very certain body type, it's very beneficial. SO don't buy WSD just because it exists,
2.Try two bikes, same model, different sizes. Example, a 15 and a 17. Try them both, understand the differences and nuances of the fit. Get to feel what too big and too small feel like, so that you can take a stab at "just right".
3. chances are first bike will not be a perfect fit, so just accept it. Getting close is good though. Most mountain bikers don't understand what they need until they've been riding for a while.

FWIW i'm 5'3 and have a 16' mtb a 15' mtb, another 16' mtb and a women's med FST.

But before you do all that, I think you should find someone who knows about fit.

What she said.

[Aggie_Ama]

Yes, some companies put care and thought into their WSD. You will look at the geometry chart and see a very distinct change in the numbers from the same size non-WSD. Some companies just "shrink it and pink it" they may use shorter cranks, narrower bars and short reach brake levers but overall it is the same bike as their men's bikes. True WSD works great for me (short torso, long legs) but my mountain bike is an unisex. The company (Specialized) uses shorter top tubes so it just worked for me. My previous mountain bike was a true WSD (changes in many parts of the geometry) and fit awesome. So find a good fitter and make sure what she needs if you are pretty worried.

I learned to ride on a "good enough fit" now on my third mountain bike I am strating to find preferences in bars, stems, suspension, tube lengths. Fit isn't as key as a road bike just don't want to be too off.