Peter Bridge asks "...What cranks are compatible with traditional French aluminum chainguards..."
In various British catalogues, adequate clearance between chainring and crankarm for such guards are noted as "GCC" standing for "gear case clearance." "Semi-GCC" is also noted in catalogues. I assume those will not have loads of clearance, but they may well work for you. Some cranksets came in GCC and non-GCC versions. Below I list those cranks that are indicated solely as GCC or indicated solely as semi-GCC in the 1955, 1958, 1960, and 1963 Ron Kitching Everything Cycling catalogues. I do not list crankset models that came in both GCC and NGCC versions, because that seems (to me) less useful to know in seeking out a specific crankset model. How would you know which it is unless you had both versions in hand to compare their measurements, or knew the proper clearance measurement you were seeking.
Campagnolo 1048 cotterless crank is Semi-GCC Chater Lea rectangular section fluted 3-pin cottered crank is Semi-GCC Cinelli Super Corsa square pattern 3-pin cottered crank is GCC Durax SC 5-pin cottered crank is GCC Gnutti 5-pin cotterless crank is GCC Magistroni No. 70 3-pin chrome fluted is GCC Milremo No. 30 3-pin cottered crank is Semi-GCC Milremo No. 50 5-pin cottered crank is Semi-GCC Milremo No. 55 5-pin cottered crank is Semi-GCC Stronglight No. 32R 5-pin cotterless crank is Semi-GCC Stronglight Type 45 five pin cottered crank is GCC in 1958 and Semi-GCC in 1960 and 1963. Stronglight No. 49A 5-pin cotterless crank is Semi-GCC Stronglight Type 49D cotterless crank is Semi-GCC Stronglight Type 52 3-pin cottered crank is GCC Stronglight Type 54 3-pin cottered crank is GCC Stronglight Type 55 3-pin cottered crank is Semi-GCC Stronglight Type 57 cotterless crank is Semi-GCC TA 1500 road cotterless crank is Semi-GCC
Some of these Ron Kitching catalogues are available through Chuck Schmidt's VeloRetro. Vintage parts queries such as this and many others can be answered using his extremely useful catalogue reproductions. Build up your personal library.
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Peter Brueggeman
La Jolla California USA
4peebee(at)peterbrueggeman.com