If my size falls in the middle of two sizes should I go smaller and longer stem or larger with shorter stem?
Make that determination by head tube height. If you want to ride low then go to the smaller frame. If not, then go larger. No point in getting the smaller frame if you’ll be using a lot of spacers to elevate your handle bars.
Stems should vary from 90-130 mm as the “normal range”. Don’t go smaller or larger.
this is a loaded question. I would say go with the smaller frame and learn to live with a spacer or two.
jwp,
I’d say I have to agree with bigskyTi. The general rule of thumb is that if two different size bicycles will fit a particular cyclist, it is recommended that the smaller of the two sizes be chosen as the one to build up.
It is much more common to learn after riding for a first season or two that one is really a little more stretched out than they feel they should be than to discover that they are not stretched out enough and need a longer top tube.
You can more easily make a smaller frame work for a slightly bigger rider than you can make a slightly too large frame work for a smaller cyclist.
Generally, as you get a seriously long stem , 120 mm and greater (too make up for too large a frame) you lose responsiveness in your steering. When you get a seriously short stem (about 70-80 mm or less) your steering will become too sensitive.
The smaller the frame, the lower your center of gravity and the better control you will have in turns. Now this may be a rather fine point when one is talking millimeters in difference, but it is true nonetheless.
Hope that helps.