1"1/8 ok on mine.
I've been running 2 1"1/8 spacers for a while now and they been fine. The headset on mine is a ritchey logic threaded one and the washer that is located between the 2 nuts is 1"1/8 outside diametre so the spacers sit on there nicely.Mind you if you find some red spacers and your silver ones are going begging i'll have them!