Actually, two things... you're right, I didn't say in my OP but, yes, I would be giving up the OCR for the Felt (or whatever). So, (N-1)+1. The original crank on my Giant came with a 50T big ring. The Ultegra had a 52T. My cadence and rhythm in general have evolved very nicely around the 50, so I swapped out the ring and am still using the 50. So, I lose nothing there. I did run the 30/38 vs the 34/30 through a calculator and I think I give up maybe an inch? OK, a bit more: 28.14 vs. 29.76. In real terms, I don't know how noticeable the difference would be. OTOH, SRAM WiFli would give me 27.9" plus the satisfaction of living with SRAM. Then, I don't know if the Z3 has a WiFli option.