I debated a long time about whether to make the quill per the Chaddock’s original design based on the A3 magneto bearings, or to redesign the quill around a matched set of ABEC-7 spindle bearings. The A3 bearings are for a 13mm shaft and have a 30mm outside diameter. The smallest ABEC-7 bearings I have are for a 15mm shaft and have a 32mm OD. There is no way to fit 32mm OD bearings in the original 1-3/8″ quill body diameter, so moving to ABEC-7 bearing would also mean moving up to a 1.5″ diameter quill body. Fortunately a 1.5″ quill body can be squeezed into the existing wheelhead casting.