I recently purchased a sweet looking gold OMAS headset at ebay. Unfortunately, it turned out to be a BMX model. Luckily, it appears that the only difference between it and road are the longer and larger diameter flanges that press into the head tube, everything else is the same. I can shorten and turn down the flanges. Does anyone know what is the ideal oversize to press into the head tube? Looking at a old headset, it appears to be .2 mm over. After I reduce the size of the flange, there isn't a whole lot of metal left. I'd like to shoot for a max diameter that will still allow the flanges to press in there, and not try and go for trial and error on this one. Is there a general rule about the amount of oversize? Also, my lathe is a big old thing with a large chuck. Chucking up the lower race, the only thing to grab on to is the delicate aluminum race housing. Can anyone recommend a good way to chuck up soft aluminum without scratching it?
Thanks in advance.
Dennis Young
Hotaka, Japan