I know this comes up a lot but just to share my limited experience,My road bike came with a 120 stem , bike shop changed it for a 110 for me and flipped it.Reason is my lower back is not too supple after a few accidents over the years. Even with the 110 on my back was still complaining so i bought a highrise 90 mm stem which gave me a very upright position ,my back stopped complaining and all was well.Obviously the downside is a less aero position which makes a big difference and also the steering was a bit more twitchy but didnt feel unsafe at all. This morning on impulse I put the 110 back on and went out for an early ride.Only did about 18 miles but felt great.Steering was noticeably more stable and defo felt faster.One thing that surprised me was I seemed quicker going uphill as well. Of course none of this is scientificly proven and I may just have been having a good day. Conclusion is that the 110 is staying on unless back flares up again but i would recommend anyone struggling to get used to a roadie position to consider breaking themselves in gradually with a shorter stem for the first few months.