Re: [CR]Mafac two cable brake lever question

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Date: Wed, 02 Aug 2006 23:02:58 -0400
From: "Joseph Bender-Zanoni" <joebz@optonline.net>
Subject: Re: [CR]Mafac two cable brake lever question
In-reply-to: <44D15725.3010102@cox.net>
To: sachshm@cox.net
References: <44D14C8D.3030909@cox.net> <44D1525E.5050506@optonline.net>
cc: Classic Rendezvous <classicrendezvous@bikelist.org>

Agreed as to no contradiction. I also agree that it is best to have the captain control all the brakes. Yes, the Pederson is a servo brake. I have the Dia-Comp licensed version and like it. I have a set of the CLB center pulls with the angled posts but I have yet to use them as they are on a long term project. Very elegant with the straddle wire being the return spring but I have never heard a review of these.

If you think about the Mafac dual cable setup you are trying to stop twice the mass with half the cable force. And half the swept area for the mass so the pads and rim heat up and the performance gets even worse. Plus the Mafac lever has poor mechanical advantage, probably second worst to a Universal.

Joe Bender-Zanoni Great Notch, NJ

Harvey M Sachs wrote:
> Joe, I'm sorry but I don't see much contradiction. My primary
> objection is to two brakes operated by one lever. We have found one
> solution (three separate levers set up so you can't do both rears at
> the same time) to work for us. Your preference still uses three
> separate levers, but chooses one that can be set to exert constant (?)
> pressure as a drag brake.
> I can't remember any descents longer than 1000' on our tandem. The
> longest was the rather steep and windy Mohonk Mt. descent in NY
> state. That was about the last time that Beloved Spouse controlled
> the rear drum and I had the two rim brakes. We were going too fast to
> be able to talk, and I could never tell when she would activate the
> disk, but I quickly learned that it could be in a turn. I'm sure that
> the paper label on the disk was charred when I checked at the bottom
> of the hill, and I believe that the disk was warped. But, we're still
> happily married some 25 years later, and she still had the gear
> shifters on her handlebars.
>
> By the way, if I recall correctly the Pederson was a "servo" brake,
> set up so that the initial contact of brake to rim tended to draw the
> pads in closer and increase the pressure. So, what Joe B-Z is saying
> about hand power is Real Important. BTW, CLB had a rather elegant
> "servo," accomplished by having the pivots pointed in toward the
> (front) wheel.
>
> harvey sachs
> mcLean va
>
> Joseph Bender-Zanoni wrote:
>
>> In some contradiction of Harvey, I think it is a good idea to be able
>> to operate both rear brakes at the same time. Having a drum or disk
>> brake as a drag brake, to take the heat load on long decents is a
>> good idea if you ride in any kind of mountains. That being said, I
>> have yet to implement it. I am thinking of a goofy looking stem
>> shifter as I already have barcons. I went out on the tandem with my
>> wife two weeks ago and the two cable front/rear Mafac lever, even
>> though perfectly set up, just requires too much hand pressure. That's
>> with a Pederson front and Mathhauser shoes on Mafac cantilevers so I
>> don't know the next upgrade except my hands.
>>
>> Joe Bender-Zanoni
>> Great Notch, NJ
>>
>>
>> Harvey M Sachs wrote:
>>
>>> With all due respect, I've only seen one application where
>>> controlling two brakes with one lever seemed appropriate. The rider
>>> of that bike was one-handed.
>>>
>>> IMHO, in all other cases there are just too many compromises to be
>>> made. 1) One lever controlling both rim brakes. Obviously
>>> impossible to modulate relative force for better control on long
>>> grades, curves and turns, etc. Since front brake is able to do more
>>> speed reduction, want it to contact first and exert more force.
>>> But, if so set up, will wear its pads more quickly, so vigilant and
>>> frequent maintenance is required. 2) (mostly tandems) One lever
>>> controlling front rim brake, dual-cable lever controlling both rim
>>> brakes. In general, leverage (cable take-up) varies between rim
>>> brakes and hub brakes, so one or the other will do next-to-nill work
>>> if actuated by same lever with same travel for both.
>>> If everything is working as you imagined it would, you can get into
>>> real trouble. One day in Corvallis Oregon on a friends Jack Taylor
>>> tandem, I got in trouble wrt oncoming car in a right turn situation.
>>> So, I hit all the brakes (two cantis on dual lever, drum on the
>>> other). Predictable result in a turn: rear wheel, "benefitting"
>>> from two brakes and light load, locked up, so rear could slide
>>> nicely toward the car.
>>>
>>> Our preferred solution is pretty simple: rim brakes separately
>>> operated by conventional single-wire road levers. Auxiliary (hub)
>>> brake operated by tourist lever mounted very low on right bar. This
>>> makes it impossible to operate both rear brakes at the same time,
>>> but get excellent modulation of rear hub brake by using it while
>>> riding on the drops.
>>>
>>> So, that's personal preference and reasons, I promise not to be a
>>> nanny if your views differ.
>>>
>>> harvey sachs
>>> mcLean va
>>>
>>> Geoff,
>>> The twin-cable MAFAC levers on my tandem are exactly the
>>> same shape as an ordinary, single cable lever. So you really
>>> can only mount them on the "hook" of the handlebar. I suppose
>>> you could try modifying the actual lever portion of the piece,
>>> but in that case, I wonder if you would get sufficient leverage
>>> to properly operate the brakes.
>>> Best of luck with the project,
>>> Fred Rednor - Arlington, VA (USA)
>>>
>>> --- geoff duke <g.duke@civenv.unimelb.edu.au> wrote:
>>>
>>>
>>>>> I am wondering if anyone can tell me if a Mafac twin cable
>>>>> tandem brake lever would work if it were placed on the top of the
>>>>> handlebars.Like a cyclocross lever.Would it be able to work
>>>>> on the flat section of bar or do they need to be on the bends like
>>>>> other levers.Thinking about setting up a single speed bike with
>>>>> canti's front and rear with one lever and considering that there
>>>>> would be a good place for it.Sorry if this question is a bit
>>>>> clunky but
>>>>> hoping for an answer,
>>>>> Geoff Duke Melbourne Australia