Originally Posted by max-a-mill
the standard for mtb's moved to 1 1/8 the same time road bikes did i believe.. but unlike roadbikes there are no mtb's still made with 1" headtubes.
also there are not many old classic mtb's still in use; at least not the way there are old classic roadbikes being converted to fixed gear all the time.
No it switched long before 1" just didn't make sense for mtbs. All of the normal problems of threaded are magnified for mtbs(especially steerer tube length) and there was no tradition of threaded so threaded was ditched shortly after the switch to 1 1/8".