You guys seem to have all the answers. I have an old Raleigh Grand Prix that i want to turn into a fixed. It has 27 x 1 1/2 tires. The hub is stamped "Brampton made in England" The side of the hub opposite the gears is threaded. Why is it threaded? Is that for a cog? If so, do 27s make a good wheel for fixed riding or should I go bigger? Any advise would help, thanks.