Getting back to you with a report on my final solution. I started by emailing Cannonade support to ask if the Ultegra junior cassette (14-28) would be compatible with the 105 drivetrain. Got their response within 24 hours that said Shimano components are generally very compatible and I should have no troubles; just install the new cassette and check the rear derailer for adjustment. My LBS shop ordered the cassette for me and installed it. Had to wait a week for the shop to fit me in...business is good. Then I had to wait through a couple of days of severe thunderstorms and heavy rains. Finally got out for a 30+ mile ride today and can now report that I am very happy with the new gearing. I especially appreciate the small incremental changes from gear to gear. I typically saw a change of 6 to 10 RPM (cadence) as I moved between adjacent gears. This is just what I was hoping for. No apparent problems from mixing Ultegra and 105; everything functioned properly. My final thought: Shimano should call these Junior/Senior Cassettes!