Originally Posted by
Lovenutz
Wasn't sure on the nomenclature, so I just called it ISO. I'm wondering if a fork with a 27.0 race installed will work with a headset that was supplied with a 26.4 race. To further complicate things, the frame needs 32.7 cups for one piece cranks / BMX.
The headset I'm buying is a Tange BMX headset (supplied with a 26.4 race). There are 27.0 Tange crown races available. I'm wondering if that will work with the headset.
I know this is a lot to ask. But I figured it wouldn't hurt to.
Of course it doesn't hurt to ask. Are you trying to use the crown race from one headset with the cups from another headset? Might work, might not, as Kontact said; headset parts even from the same manufacturer are not usually compatible unless they are the same model, only made to a different dimensional standard.
The mishmash of dimensions on a headset comes about because neither the crown race nor the cup skirts nor the threading cares at all what the others are. You can theoretically mix and match them any way you like. MOST of the time, BMX headsets have 26.4mm crown races, but not necessarily.
Be aware that the BMX cup skirt standard is bigger than either of the other aforementioned standards and incompatible. (At least Sheldon Brown got that one right, unlike his ISO headset dimensions. He missed that one.)