CUP SKIRT DIAMETER INFORMATION

The cup skirt is the portion of the headset that fits into the head tube. 

Standard 1 inch headsets have a cup skirt diameter of 30.2mm. 

Old School 1 inch BMX headsets have a cup skirt diameter of 32.8mm.

Here are the complete specifications (all measurements are in millimeters, weight is in grams)

  Weight
(g)
Stack Height Lower
Stack
Height
Cup Skirt Head Tube
Inner Diameter
Base Plate
Inner Diameter
Fork Crown
Inner Diameter
1 inch 2Nut™ - Standard 94 37.4 12.9 30.2 30.1 26.4 26.5
1 inch 2Nut™ - BMX 110 39.1 13.7 32.8 32.8 26.4 26.5
1 inch GripNut™ - Standard 93 33 to 38 12.9 30.2 30.1 26.4 26.5
1 inch GripNut™ - BMX 107 34.2 to 39.2 13.7 32.8 32.8 26.4 26.5
1 inch NoThreadSet™ - Standard 84 28.0 12.9 30.2 30.1 26.4 26.5
1 inch NoThreadSet™ - BMX 99 32.0 13.7 32.8 32.8 26.4 26.5