Originally Posted by bigbossman
OK - so I started to build the Palo Alto tonight, and went to install the headset first. I have a box full of take-off threaded headsets, all from Japanese bikes. I pick the nicest, shiniest one and go to set the crown race. Plunk - it drops right on, and is obviously too big in ID to fit snugly on the steerer tube. I try all of my crown races in succession - same deal.
What gives? According to my caliper, it looks like the ID of all my available crown races is about 1.065", which converts roughly to 27mm. As you might recall, the frame is Italian made from Columbus SL tubing. Do I need something special for this? Anyone have a crown race that is slightly smaller?
The headsets from the Japanese bikes probably use the JIS (Japanese Industry Standard) size headsets, at least for the crown race, and the Palo Alto may use the ISO standard (or the smaller of the two Italian standards as mentioned above). JIS inside diameter for a crown race is 27.0mm, the ISO inside diameter is 26.4mm. Here's a link to Sheldon's site showing the different dimensions:
http://sheldonbrown.com/gloss_ha-i.html#headset