I have always liked half-step. As pointed out above, 49-46 is a classic chainring combo, mainly because it works so well with a 2-tooth progression in back.

I currently run the Bianchi with a 1.5-step 50-42 / 14-16-18-20-23-26, but I can swap in a 47 for the 42 for flat work. If I wanted a higher top end and a lower bottom gear, an 8-speed cassette would still make sense with the 50-47 (or a 49-46): 12-14-16-18-20-23-26-30, or add a 34 or 36 with a 9-speed.

Another half-step I really liked was one I put on the Peugeot PKN-10: 48-45-34 / 13-15-17-19-21-24. Again, start with 12T for a higher top gear and end at 28 or in the 30s for a lower bottom gear, and once again half-step (this time with granny) still makes sense with 8 or 9 cogs in back.




The only problem I have experienced is that many of the newer spiders are too thick for a 3-tooth drop between the two outer chainrings. Unable to do 53-50-39 on a Campag. Veloce, I ended up doing half-step-plus-overdrive, with 50-42-39 / 13-15-17-19... , which is not as satisfactory, but interesting, anyway.