We designed Aspero to fit most 700c x 42mm or 650b x 49mm wheel/tire combinations. Of course, there are variables—rim width, tire casing, and tread depth—which will affect final clearance. We (and the International Organization for Standardization, or ISO), always recommend 4mm of clearance between the tire and frame.
**New Shimano Road (not gravel) 12 speed front derailleurs reduce tire clearance in the rear of the frame to 700x38c or 650x45b.