My lowest gear is a 30/34 which is fine for most rides but I have some super tough gravel events with brutal hills (long sections of 20% gradients and even 30%) and estimated ride time of 10 hours.
I was wondering if I can alter the gearing to go lower? Are there any different cassette options that would work. 30/36, 30/38 etc? Thanks.
I consider myself a decent climber but some of these hills are savage and the wearing down effect will be challenging.
There are ways to make 2x GRX work with 11-42 cassettes but they aren’t officially recommended. You can convert to 1x and get access to larger cassettes with the 1x GRX RD.
Google around and you’ll see many people are using 11-40/42 with 2x GRX but iirc the shifting gets sloppy in the large gear area.
If you need a bit more help getting an 11-40 to work a Goatlink might help. It gives you a bit more room to clear the big cog, but you might find the derailler itself can do it with the right b-screw setting. Good luck!!!