I have a 1991 GT Tequesta mountain bike. It has a ritchey threaded headset. I want to replace the factory solid forks with a set of suspension forks. I have found many threaded forks on ebay stores but don't know how the industry standards are measured. For example my steerer tube on my factory forks are O.D. (outside Diameter) is 1.125" or 1 1/8" but the I.D. (inside diameter) is 1". Is the industry standard measured from the O.D. or the I.D.?
Next I need to know the correct legnth forks to buy. My factory forks steerer tube is 6.75" long. This equates to 171.45mm long. Should I buy the 170mm legnth or the 200mm legnth and cut it? I would think the 170mm cause 1.45mm in legnth is not a drastic enough of a distance to me. I am not sure I would want to try to cut a long one down to size for 1.45mm.
Any help is greatly apreciated.