All City Bicycles Nature Cross Frameset. Cyclocross and the Nature Cross Frameset go hand-in-hand, and it’s not exactly surprising with the speed and agility offered by this crusher frameset. It’s the ideal option for those who swear by steel frames, and it’s sure to get us to the top of the podium. With A. C. E. steel tubing, the Nature Cross Frameset is light, fast, and stiff. It tears through tight turns and quick up and downs with ease. An ovalized top tube lets us power past anything in our way with our bike on our shoulders, and the Columbus Futura fork is specifically designed for uneven and slippery surfaces. This frameset boasts tire clearance for 42mm 700c tires that enhance durability and performance, too. A few signature details like custom dropouts and reinforced bottle bosses help this frameset stand out from the crowd so we can feel proud of our burly steed no matter who is riding against us.