Here is what I did with a 16.5" Trek 930. This is one size down from what I would ride as a mountain bike but has an effective top tube length of 54cm, right in my wheelhouse for a road bike. The handlebars are Civia Emerson short reach, short drop bars with a 26mm clamp diameter. The bar ends are Shimano 8 speed. I have been using it as my fair weather commuter. I love it and recently added cyclocross interrupter brake levers.
P4120228 by
galoot_loves_tools, on Flickr