Hi Kurt. OMAS is an odd bird. Most road headsets used 5/32" bearings. Campy typically used 3/16" which never seemed to wear well. Some Schwinns and Ritcheys, i believe used 5/32" bottom w/ 1/8" on top. It's usually a good idea to use new bearings and to remove 2-3 balls from each cup so they're not all; jammed together. It's also hard to keep the loose bearings in place, esp. when they're so small. Usually i pack both head cups [top and bottom] w/ grease and bearings. Then i put the adjustable cup on the upper head race and rotate it a bit to seat it. Now, while keeping downward pressure on the adjustable cup, i insert the fork up throught the head tube until the steering column engages the threads on the adj. cup. Maintaining downward pressure i thread the adj. cup onto the steering column of the fork - drawing it straight up till the fork crown race seats in the lower head cup bearings. This way the bearings are less likely to be spun out of their tracks. If you've got some "typical" 5/32" retainers you might want to see how the headset works w/ those just a test run to see if that's the size they were intended for. 1/8" seems small but perhaps another list member can confirm or deny that this is the correct OMAS/Colnago size. Good luck. Billy Ketchum; Chicago, IL; USA. ----- Original Message ----- From: "Kurt Wolko" <satbuilder@yahoo.com> To: classicrendezvous@bikelist.org Sent: Friday, March 27, 2009 7:14:16 AM GMT -06:00 US/Canada Central Subject: [CR] Colnago/Omas headset All, I am in the process of overhauling the headset on a '78/'79 Mexico and since I haven't done one of these in a real long time I thought it best to ask. The headset is a Colnago, which from reading previous posts I am guessing is an Omas. There were 30 ball bearings on both top and bottom, 1/8 inch in diameter. Does that sound right? My copy of Sutherland's doesn't list Omas headsets. The headset appears to be in decent shape, at least from my untrained eye. There is a small dark ring around the lower race on the steering tube. It doesn't have any pits that I could notice. Other than that, all the races and cups looked decent. I degreased everything and reassembled it with new grease, then began to adjust it by rotating the forks while lightly hand tightening the upper cup. Then I checked for play by pressing against the dropout, and continued to readjust until the play was negligible. When the play is virtually gone, the headset feels like it's binding/grinding, and I'm pretty sure it's not supposed to feel like that. I reused the ball bearings, but maybe that isn't a good idea. Maybe I need to get some new bearings and try it out again. I do have a super record headset I am thinking about using in place of this one but am not sure yet I have a problem. Thoughts and comments are appreciated. Kurt Wolko Owings, MD