I’m trying to upgrade my gravel setup..I ride a 2018 Diverge (road geometry) and I love that bike but sadly no UDH. I 'm running Ultegra 11 speed shifters, a GRX 11 speed rear D, a 11-42 cassette with a 40 or 42 up front (1X) and GRX cranks… so to be economical I figure I might get new 12 speed GRX shifters, a 12 speed GRX rear and of course the cassette. I see the 11-46 cassette but the jump from 37-46 is nuts. I realize whether I go SRAM or Shimano, I’ll need a new rear wheel as I currently have GRX 870s.
Michael..that is an excellent question…. as I wrote, I run a 40 with an 11-42 cassette…I would like to have a smaller gear as the 40/42 sometimes in not enough on loose steep stuff and if I put a 38 on up front, I’ll spin out on flats, etc. Ideally I’d like a 40/42 up front with a cassette that give me a bit more spin than a 42.
SRAM makes an 11 speed 10-42 cassette. If you could fit that - you’d need an XD freehub body - you could switch to a smaller chainring without spinning out, gain an easier gear, and keep your current derailleur and shifter.
You can look into the effects of alternative gearing setups via https://www.gear-calculator.com/, which includes the ability to compare two different drivetrains side by side.