Moderately (at least) sticky hub threads
I figured I should ask about this now rather than strip the threads of my hub. I have a 1973 Motobecane Mirage that I am converting to a fixed gear. It came with a Japanese freewheel, so I was hopeful that an ISO cog would fit. To make sure, I tested it with a Dura-Ace cog borrowed from a friend and it went on effortlessly. The lockring I bought for it also slides on all the way without any effort.
However, the EAI cog that I purchased to use on it does not fit perfectly. It slides most of the way on but then encounters resistance with 4-5 mm of space between the hub flange and the cog. I am sure I could force it, but obviously don't want to strip the hub threading. Are there really differences that significant between the nominally identical threading on track cogs? Do I have a defective cog?
Has anyone else had a problem like this before? Your thoughts are appreciated.