I know I say this for everything -- but doesn't Park Tool make a tool for this?
Oh, wait, photo in post #1 says "made in France". So I presume a different size and the tool does not fit.
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Larry:1958 Drysdale, 1961 Gitane Gran Sport, 1974 Zeus track, 1988 Masi Gran Corsa, 1974 Falcon, 1980 Palo Alto, 1973 Raleigh Gran Sport, 1974 Legnano. Susan: 1976 Windsor Profesional.