Originally Posted by
ThermionicScott
"Constantly"? Not in my experience. With the right chainring and cassette pairing it's more like "hang out on the middle ring 95% of the time, and shift to the big or small rings for extreme terrain."
Part of the issue may be that my area (SF Bay Area) tends toward more extreme riding, so my experience was the opposite, maybe 5% on the middle ring. I would either want the big ring or the small ring, and the middle one was never low or high enough for general use. On the flats, I'm fine with the standard 50t and 11-28 cassette, which I'm usually right in the middle of the cassette, with good room to adjust up or down. I can see where the 16t cog would be nice.
If you're spending 95% of the time in the middle ring, it seems like a 12-25 cassette and 50/34 compact would be about ideal, although a 48/34 is probably closer. Tight spacing and you can drop down to the 34t for strong headwinds, etc.
That IRD 46/30 crankset is the first one I've seen. If you go to Chain Reaction and look through their selection, there isn't a single crankset like that. The closest is an XTR 44/30t. The major manufacturers are definitely not on-board yet.