"Dropping" a Mafac Racer (or any caliper) seems simple, using a thick piece of drilled flat stock. The drop distance will need to be sufficient to allow the bolts and nuts to clear the bottom of the fork crown and top of the bridge, so a 10mm drop might be the minimum, unless the bolts were threaded into a thicker piece of stock used as the drop hanger.
I would be sure to use a large-head bolt (like the original) thru the caliper's bridge, to reduce stress, but that might be very hard to find. The original bolt thus may need to be sleeved along it's unthreaded length to tension it under the crown, and the upper bolt need be of good quality.
My '79 U09 came with Weinmann 610's, and when I switched to a narrower, alloy Mod58 rim, the pads would hit the tire even when placed to the bottom of the slots! I had to really file the slots for the new (still 27") rim (seemed weird). Obviously they took fender clearance seriously (just like on my Viscount).
David Snyder
Auburn, CA usa
> Listers,
\r?\n>
\r?\n> One of the biggest issues with our Peugeot UO-18s was that Mafac Racers no
\r?\n> longer reached the braking surfaces of the 700C alloy (OT Mavic Open Pro)
\r?\n> rims that replaced the mixte's original steel 27" Rigida
\r?\n> "death-in-the-wet" rims. It took me a long time to find two sets of used
\r?\n> Weinmann 750 centerpulls, and I still have the original Racers in the
\r?\n> garage. And since (in all likelihood) I will be going through this process
\r?\n> again with another "perfect-fit"
\r?\n> UO-18 Mixte, I'd just as soon use up the inventory I have this next time
\r?\n> around. But I still need another 5-8 MM of brake reach out of those
\r?\n> Racers.
\r?\n>
\r?\n> Have any of you ever heard of, thought about, designed, made, seen,
\r?\n> purchased, or used a drop bolt (similar in concept to the ones used for
\r?\n> Campi and Suntour Superbe brakes) for Mafac centerpulls?
\r?\n>
\r?\n> My initial pondering (while waiting in the lobby to report my bike's theft
\r?\n> to the Alameda Police Department) lead me to believe that such an item
\r?\n> would actually work and might not cost too much. And a UO-18 mixte only
\r?\n> needs a few silly millimeters of drop (5-8?) to make this concept work.