Originally Posted by
geepondy
Yeah I posted quite a bit about it in another thread. I'm 5'10" and I tried a 56 cm Roubaix and a 54 cm Roubaix Sport. The 54 put me in a more upright postion which I liked and not that much more aggressive stance meaning the seat adjustment was not that much more higher than the handlebars for the 54 over the 56. I definitely like being more upright. But everyone I talk with seems to think at my height I should go with a 56 cm. I spoke with a professional bike fitter at a different shop and he says no way he would fit me on a 54. But as he mentioned there also is a lot of variances between the different bikes.
If choosing the 56cm Roubaix I'm saving $600 but giving up better wheels and going down to Tiagra vs 105.
I'm not totally sure how you'd be more upright on a 54 vs. 56; handlebar should feel closer and lower on the 54. I'm also 5'10" and ride a 54 with a 110mm stem. However your body is different from mine so YMMV.
To answer the question, the stock stem is a proprietary Specialized one since the diameter of the FutureShock is smaller. You'd need to purchase their stem adaptor to use a standard 1 1/8" threadless stem. The way you adjust the bar/stem height is by removing the FutureShock and adding/removing spacers below the shock boot, then reinstalling; the stem will always sit on top. Its relatively minor and realistically 20-30mm IIRC you can play with before changing the stem angle and headset cap. In my set up below, I use a 0 stack headset cap, 110mm stem at -6 degrees, it's the lowest I can go without going to a different stem with more angle. Obviously you can flip/flop and adjust things to your liking.
