Quoth Baird Webel:
>I recently acquired a Masi 3V and am trying to install a Mavic
>headset on the fork. The headset will thread slightly onto the fork
>and then bind. The headset is marked 25.4x24 and a similarly marked
>Campy headset does the same. The more generic asian one inch
>headset parts that I have thread on just fine.
>
>From reading Sheldon Brown's site on headset threading, I am
>guessing that the Masi has an italian-threaded fork and that the
>Mavic/Campy have a slightly different threading (ISO vs. JIS?)
ISO vs. J.I.S. has nothing to do with the threading, which is also the same as BMX headsets.
The differences among these three systems are all in the press-fit dimensions for the two head race and the crown race on the fork.
There is a VERY slight difference in Italian vs standard steerer
threading. Same diameter and thread pitch, but cut with a 55 degree
point in lieu of standard 60 degree. In practice it doesn't matter.
>and thus will not thread on while the asian headsets will? Can
>anyone confirm this? I am assuming that I can run a cutting die on
>the threads and fix the mismatch?
No, you don't need to (and shouldn't) re-cut the threads, but you might check the very ends, maybe clean up the start of the first thread with a file held at about 60 degrees to the steerer.
I believe your problem is likely just tighter manufacturing tolerance on the Mavic headset. Perhaps a bit of lube on the threads and a bit more persistence will get it running fine.
Sheldon "Manufacturing Tolerances Sometimes Add Up" Brown
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| Oh, my ways are strange ways and new ways and old ways, |
| And deep ways and steep ways and high ways and low, |
| I'm at home and at ease on a track that I know not, |
| And restless and lost on a road that I know. |
| --Henry Lawson |
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