i have an iron horse 7point3 from 05, i should run 170mm max according to ih. i want a 66rc3 for some reason, but i also want a 55 ata, 55 ata is 120-160, but i worry that the air aspect won't hold up. 66rc3 is 180mm and i know will hold up but costs more. i want to run the 55 ata for weight reasons and the ability to use adjustable 120 travel for climbing. i think its enough for what i need, it will eventually go to an sxtrail if i get one.