ok look at the reading on the caliper its 73.76 and then look at the adapter for the sealed modern BB on the left side of the photo there is a slight gap where the adapter isn't snug against the frame. I have the bolts tightened nice an snug and I gave the adapter a few sharp raps with a hammer ( of course I had a nice thick piece of wood against the adapter) and it feels like its home but the other side seated snug against the frame. Isn't that supposed to read 68 mm? Do I need to take the adapter to the lathe and turn some material off the back to get my proper dimension or is it gonna be ok this way.