I have a Mavic headset at home 1 1/8, threaded.. not sure what number it is but it's in it's box so i'll have a look if you want (i.e is what you need 1 1/8 threaded..
I use ATACs on all my other bikes and love them but want something a bit different on this ride. I'm willing to have a pair of shoes for use on this bike only