My first MTB, vacation pics, and advice needed.....

[Triskeliongirl]

Thanks for all the helpful replies. The guys in my LBS say I am a S, not XS. The bike I have has a standover of 28.5" and is a S (15.5"). My cycling inseam is 30.5" and I am 5'4". My road bike is a 48cm cervelo RS w 650C wheels and it fits me like a glove. I have found some 29ers (Julianas) that give me the 28.5" standover and work with an english threaded bottom bracket (requirement of my custom crank), so those are also future candidates. The 27.5" wheel is also attractive. But for now I need to select chain rings for the custom crank. Do you guys think I am making a mistake if I go with 22/38, even if I don't have my final bike picked out yet (or decide to never upgrade, or wait a few years before upgrading). This gearing will get me nice an low on the bike I have since its a 9sp 11/34, but if I get a new bike, even with bigger wheels, I can go up to 36 or even 42 so I will have lots of options. Or is 22 ridiculously low?

I should add that this is hard, because while I love my LBS, at this point in time they only carry specialized which uses a BB30 bottom bracket, have fixed position FDs (not good for adjusting over my custom elliptical offset rings), and most models have high standover. They will also do orders from MOOTs, but those are very expensive, and also don't offer much in standover on the 27.5 models. The Moots YBB was recommended by Cassie here, but its just not clear to me why it will be so much better than the bike I have already. Also, I didn't feel beat up on the hardtail, so not sure I even need the weight of the YBB. I guess what I am really trying to understand is why I would enjoy a more modern bike. That is why I think I need more time on the bike I have, to see what I want next.