From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Why are centerpull road brakes obsolete?
Date: 19 Mar 1998 19:29:28 GMT

Larry Leveen writes:

> What (if anything) makes centerpull road brakes undesirable and/or
> obsolete?

They have severe cosine error (the pads sweep up into the tire with
wear), they have a third member, the bridge, that adds a degree of
flexibility above that found in the caliper arms, they use a straddle
cable that changes the mechanical advantage as pads wear, they require
an anchor for the brake cable that interferes with the head bearing or
seat bolt, their mechanical advantage is approximately the same as the
side pull brakes of the day (1:1), and they have no convenient quick
release.

The heyday of the centerpull was about 1960, especially in France, and
was a major engineering blunder that was sold on the basis that it had
a higher mechanical advantage, which it couldn't have, given the hand
levers and the constraints of human hands.  Of course it didn't have a
different ratio, but it looks as though it does.  The canterpull
vanished from the professional ranks when Campagnolo introduced the
first reasonable sidepull brake in the early 1960's.

Jobst Brandt      <jbrandt@hpl.hp.com>

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: Anyone still use Brooks saddles?
Date: 3 Oct 1998 19:48:12 GMT

Anonymous writes:

>> That concept is like the old one put forth by nincompoops about
>> Campagnolo (racing) brake"s

> Sorry, I missed this one. What does this comment refer to?

The truncated text referred to the following:

. That concept is like the old one put forth by nincompoops about
. Campagnolo (racing) brake"s: "They're made to control speed, rather
. than for stopping", the response to people who complained about high
. hand lever force.  The speed control a racer needs, is coming down
. from 35mph to practically a stop on Alpine descents into hairpin
. turns.  If that ain't stopping I don't know what to call it.

There was nothing wrong with these brakes except the sales staff or
maybe the non-athletic types who have insufficient grip to operate
them.  Of course Shimano rose to the occasion and upped the mechanical
advantage from 4:1 to 5.2:1.  That's how we got to dual pivot brakes
that must run with so little clearance that racers regularly open the
QR on long climbs because the brake drags.  The higher mechanical
advantage demands a self centering brake (two pivots) with low pad
clearance to not run out of lever travel... which they do anyway when
ridden on wet descents.

Jobst Brandt      <jbrandt@hpl.hp.com>