André Leducq was a brand name (as were Antonin Magné, Francis Pellissier, Lapébie, and about half a dozen others) used by Mercier both pre and post WWII. I have a really nice Andre Leducq frame from 1939 which was one of four imported into the UK.
The Mecadural frames were post WWII. I have a 1949 Mercier catalogue which shows an almost identical Mercier branded Mecadural frame. All the Mecadura l frames to my knowledge have chrome steel forks and mostly come with a Meca Dural headbadge. They are not especially rare in France - I think they are quite tough. They are not especially light (about 1.8kg for bare frame according to the catalogue which would accord with the frames I have handled) and are made from Alumag tubes joined with internal expanders in the lugs. Alumag was a trade name for a series of aluminium magnesium alloy s - from memory I think these are similar to some 5000 series aluminium alloys. Meca I think refers to the joints being mechanical ie with expanders. They were only rarely made as pure racing frames I think (I have never seen one - all the Mecadural frames I have seen are light touring frames in both diamond and open frame versions) though their catalogue make s mention of a racing frame. Significantly the top end steel racing frame was very similar in weight to the Mecadural one.
regards
Hilary
> From: "David Fryer" <maximalist@bigpond.com>
> Date: Wed, 16 Mar 2005 19:59:08 +1000
> To: <Classicrendezvous@bikelist.org>
> Subject: [CR]Mercier mecadural
>
> Re: Mecadural Andre Leducq alloy frame on Ebay.
>
> This, for me at least, is interesting. I have an identical frame,
> but it is stamped Mercier on the rear drop-out, with a frame
> number of 3763. There are no other markings.
> Attempts to establish a build date have so far proved fruitless.
> My guess is 1930's, which would mesh well with Andre Leducq's
> Tour de France win in 1930.
> Unfortunately, mine is missing the headbadge, so I don't know
> if it is a Mercier, a Mecadural, or a Mercier Mecadural.
> Is the Ebay frame actually a Mercier? What connection, if any,
> do the frames have? Dural is an abbreviation of duralumin -
> an aluminium alloy, but what is "meca"?
> Any suggestions from the learned out there?
>
> David Fryer, Brisbane, Australia.