My Force 1x crankset came with a 42T chainring and I considered going with a 11-46T cassette but instead I opted for a 38T chainring and 10-42T cassette, which results in almost the exact same gearing. I went this route so I could have a lighter cassette but you do need to get a XD freehub for your rear wheel. While the RX812 probably could shift the 46T, and almost certainly with a roadlink, you should have no issues the 42T big cog. Not sure about 10T small cog though as it's rated for 11T. Are you set on Shimano GRX vs Sram Rival 1x?
Last edited by loheiman; 11-23-19 at 10:30 PM.