I have repalced all the fasteners on my bike with titanium, except for the four in the Ritchey stem, they are 7mm. After searching several web sites, and talking to the people at SRP, which is here in town, 6mm and 8mm is about it in Ti. There must be some out there somewhere. ( Yes, for us gram obsessed people, it does make a difference of about 4 oz. for all the fasteners on the whole bike ) And yes, they are not cheap !