Rear gear arrangements have evolved nicely. Why haven't we seen similar advances in front gear systems? One would think that narrow chains suitable for nine or ten speed rear cassettes would enable smooth, broad four or five speed gear clusters on the front. As a tourist with a heavy bike, trying to make the most of momentum on highway hills, I appreciate very broad options - from 28 X 34 on the uphill to 54 X 11 on the downhill. A smoother, broader front shifter would be a great thing. What are the obstacles to getting such an option to market?