I come from a mountain biking background and recently purchased my first new gravel bike (Pinnarelo Grevil). It has a 1x Shimano GRX drivetrain (42T chainring and 11-42 Cassette). After riding about 15 miles of gravel, the amount of dirt accumulation is excessive. My legs, the entire bike, and the chain/cassette get filthy dirty. My two water bottles are completely muddy (condensation from the ice inside and the dirt). I know this is part of dirt riding, but I'd have to go on 20 mountain bike rides to accumulate the kind of dirt I get from half of a single ride with my new gravel bike.
Problem is that after the first 15 miles, my drivetrain completely dries out and starts making lots of noises under heavy load (while climbing using the lowest gear). I usually go on 40+ mile rides and I think it's unreasonable to have to clean and re-lube during a single ride. I clean my chain and cassette after every ride and use dry lube (Rock N Roll or ATB lube), but it still makes grinding noises after 15 miles of dirt riding. To test, I used a wet lube and it seems to perform much longer without grinding noises, but the chain is filled with grime since wet lube attracts more dust and dirt.
Why does my gravel bike get so much dirtier than my full suspension mountain bike? On my mountain bike, I have the SRAM Eagle 1x drivetrain and the dry lube easily lasts my entire ride without any grinding noises. Is this due to a gravel bikes geometry? Maybe it's my tires? Is there another type of dry lube that lasts more than what I've been using? Or could there be another cause for my grinding noises? The attached picture is after 5 miles of dirt riding.
Pinarello Grevil