I seem to recall a list member offering some very nicely made stiffeners
for Mafac center pull brakes. If anyone is seeking something like this,
an archive search may yield the list member. Jay Sexton Sebastopol, CA
Message: 14 Date: Mon, 7 Dec 2009 19:44:14 -0800 From: David Snyder
<dddd@pacbell.net> Subject: Re: [CR] Spence Wolfe Bikes / brakes To:
<classicrendezvous@bikelist.org> Message-ID:
<1B2436D7E8C842D4B65773FA78853C56@ddddPC> Content-Type: text/plain;
format=flowed; charset="iso-8859-1"; reply-type=original Yes, an arch
stiffener can quell squeeling by preventing the pivot posts from
splaying out in response to pad contact forces. On the front caliper
(where forces are highest) the pads of any centerpull or cantilever
brake will toe-out as the pivot posts splay out, so squeeling can get
worse as the brake is applied harder. On the rear caliper (which is
backwards to the front caliper) the pads toe-in as pad contact force
increases, making squeeling likelier when the brakes are applied
lightly. In both cases, the toe-in and toe-out motions affect pad wear
as well as pad contact angle, and pad wear affects contact angle in
turn. With use, contact angle wears in to an equilibrium toe angle. I
had to make a Spence-type brace for the Weinmann brakes I used to use on
my 700c Pedersen racer that I used to race XC on. Not for squeeling, but
to prevent the lever from bottoming on the bar grip when descending with
wet rims. I hadn't yet seen a Spence Wolfe-type brace before but the one
I fashioned looks identical (minus the holes) to the one's we're talking
about, and they work as intended. I also made one for my road-going
Peugeot UO9 to prevent squeel when using grippier pads. That one was
made from a broken-off bottle cage bracket (holes already present),
filed to shape to clear the tire. I have made big arches for
off-road-going cantilever brakes also, these with deeper sections to
resist flex since they have to drop down a few inches from atop a fat
tire to the canti bosses. After market versions for canti's and
centerpulls have come and gone some ~10 and ~25 years ago, respectively.
NOS steel versions for Mafac have appeared on Ebay in recent years.
Eliminating squeel on my Gitane TDF's front Mafac was proving difficult
until I really mashed on the front brake one day, which sort of crumbled
the rear-most of each pad's 4 mini-pads. You might say that I taught
them a lesson. David Snyder Auburn, CA usa ----- Original Message -----
Subject: Re: [CR] Spence Wolfe Bikes
> > Thanks John for the Spence Wolfe feature tip of Mafac Competitions with
> > stiffener. I have one Mafac Racer in my spares that has a stiffener
> > installed
> > and wondered what the heck it was. It consists of an eigth-inch thick
> > aluminum plate, half-inch wide and shaped in an arch spanning the arms and
> > fastened with ugly allen bolts in place of Mafac's chromed hex-head pivot
> > bolts.
> > I wonder if this was an attempt to quell Mafac squeeling or will different
> > pads cure this as well?
> >
> > I'd like to emphasize by paraphrasing Jerry, that many, if not most, of
> > Spence Wolfe's modifications weren't necessarily exclusive and were common
> > custom touches available from the "better" shops.
> >
> > Anyway, thanks to all the responses from list-members in regard to my
> > query.
> >
> > Jack Romans
> > Sacramento, California