Two things to keep in mind when brazing on Mafac cantilever bosses. First, they are different front and rear. The rear ones have a little more offset than the front, as stays are generally wider spaced than fork blades. Second, don't forget to braze the stud to the bracket when you braze the bracket to the frame. Otherwise, they will loosen up in service and you will be destroying a nice paint job when you have to rebraze them when they come back after the first ride.
Never made that mistake myself, but I have fixed it on another frame. Canti brazeons were a popular addition at the turn of the '80s.
Steve Barner, Bolton, Vermont
> Date: Mon, 8 Mar 2004 05:38:15 -0800
> From: Jan Heine <heine93@earthlink.net>
> To: classicrendezvous@bikelist.org
> Subject: Re: [CR] Classic Mafac Cantilever Brake Question?
>
> >Can anybody tell me if Mafac Criterium cantilevers will fit modern
> >brazed on cantilever bosses? This is the type with the three
> >tensioning holes.
>
> As far as diameter and length of the boss are concerned - YES. I have
> switched from relatively modern (1990s) cantilevers to Mafacs and
> back. For spacing (how far the bosses are apart): With original pads,
> the Mafacs need bosses that are spaced a bit further apart than many
> modern cantilevers, it seems. Modern, thinner pads will reduce that
> distance. Most bosses today are offset to the inside, because mtb
> forks have their legs very far apart. (I have a Mercian with Cinelli
> fully sloping crown and canti bosses, where the bosses are closer
> than one would like. Still works great, but not with original pads.)
>
> Basically, before you do the work, make sure your forks leave enough
> distance between rim and fork leg to fit the brake pad...
>
> Also, I have absolutely no experience with V-brakes and the associated
parts.
>
> >Can original Mafac brazed on frame bosses still be purchased?
>
> Ask somebody like Mercian who have been in the business for a good while.
>
> --
> Jan Heine, Seattle
> Editor/Publisher
> Vintage Bicycle Quarterly
> http://www.mindspring.com/