Centerpull brakes

Though I've been critical of Grant Peterson's effort to revive
centerpull brakes, I have to admit that the latest Rivendell Reader
(#30) gave me reasons to pause.

First of all, in the letters section, a reader (Thomas Papetti) points
out that
dual-pivot sidepulls won't track an out-of-true rim the way all other
brake types will. I'm not sure how much that counts in favor of
centerpulls (Papetti doesn't discuss them at all). Even though most
riders would probably use long-reach dual pivots in lieu of
centerpulls, long-reach single-pivot sidepulls and cantilevers are
still available if tracking is a significant worry.

Then in an article, Jan Heine makes several claims for the superiority
of sidepulls.

He says, "The long lever on the cable side [above the pivot, if I
understand him correctly] and the short lever on the pad side [below
the pivot] gives centerpulls a huge mechanical advantage over
sidepulls. Just like a bolt-cutter, where long arms and short jaws
allow you to cut through thick steel bolts." Later on, he adds that
only with the advent of dual-pivot brakes did sidepulls catch up to
centerpulls in this respect.

That doesn't seem to jibe with Jobst's discussion in the FAQ, which
seems to suggest that single-pivot sidepulls and centerpulls had the
same mechanical advantage.

He argues that only the part of the arm below the pivot needs to be
beefy, because that's the only place where flex matters. "As a result,
the arms above the pivots can be incredibly skinny, as they don't need
to resist flex. That is where the weight savings of a centerpull
originate." He doesn't say what the weight savings is.

He writes, "And since the pivot on centerpull brakes is on the fork
leg, adding reach does not increase the flex or change the mechanical
advantage. So there is not incentive to go to short-reach brakes." I
think he means that since the distance between the pad and the pivot
point always remains the same, adding lever length above the pivot
doesn't effect the mechanical advantage. That sounds dubious to me --
doesn't changing the length of a cantilever brake's straddle cable
effect mechanical advantage even if all else remains the same?
Furthermore, from the photos of old centerpulls in the Reader, it
doesn't seem as if the distance from pivot to pad was always kept
constant (some long-reach brakes seem to achieve that reach in part by
increasing the lever below the pivot).

He notes that centerpulls don't stick out to the side like
centerpulls. It seems to me that that problem can be cured by using
v-brakes, though that introduces problems of its own (e.g., mating
them to road levers).

He says that even the standard-reach (what would be called long-reach
by most) dual-pivot brakes offered by Shimano don't leave much room
for fenders. Is that true? Just how big a tire would you have to run
before you would crowd out the dual pivots? (Elsewhere in the Reader,
Grant says that centerpulls will clear a 40mm tire or a 38mm tire with
fenders; what's the limit with the current long-reach dual pivots?)
Furthermore, why not long-reach single-pivots, which are still
available?

Probably his most controversial claim is that single-pivot sidepulls
"offered inferior performance" and became widespread mostly because of
Campagnolo's advertising and gruppo packaging. Contrast that with
Jobst's claim in the FAQ that, "The centerpull brake of the 1950's,
was popular for nearly a decade,
in spite of being entirely without merit, being worse in all respects
than the side pull brake with which it competed."

In the past, I've been pretty fed up with Grant's talk of reviving
centerpulls, because it so often appeared side-by-side with complaints
about Rivendell's financial straits and lack of popularity. I do
notice a more refreshing tone in this issue: he mentions a bike
planned for next year that will have braze-on pivots for centerpulls
and adds, "But we don't expect anybody to follow that lead., and we
fully expect to sell fewer bikes because of it. Centerpulls, for as
much sense as they make, will still scare off most customers."

(Gary Young) writes:

Though I've been critical of Grant Peterson's effort to revive
centerpull brakes, I have to admit that the latest Rivendell Reader
(#30) gave me reasons to pause.

Back in the eighties I was a great fan of centrepull brakes, partly
because I believed them to be greater in stopping power but mainly
because I found them much more easy to adjust. That is, in my opinion,
a big benefit!

As you point out they give considerable and equal leverage to both
blocks, acting symmetrically on both sides of the rim. This certainly
looks to me to be better leverage than the single pivot calipers that
were current at the time. However, cantilever brakes have at least
equal leverage, are lighter, are more securely mounted to the bike,
and are even easier to adjust - for a very small penalty in wind
resistance. Where ultimate speed is not the issue they seem to me to
be definitely preferable over the older style crossed lever
centrepulls. If ultimate low windage is a consideration you're
probably going to use dual pivot calipers these days anyway.

I know that V brakes have largely taken over from cantis, but
personally I'm not yet persuaded that they offer a real practical
benefit for most uses - I think they're more of a style statement, and
the special levers mean that they're not so easy to interchange with
other components. But I can't now see any reason to prefer old-style
crossed lever centrepulls to cantilevers.

--
(Simon Brooke) http://www.jasmine.org.uk/~simon/

my other car is #Subr-Car: #5d480
;; This joke is not funny in emacs.

Simon Brooke writes:

I know that V brakes have largely taken over from cantis, but
personally I'm not yet persuaded that they offer a real practical
benefit for most uses - I think they're more of a style statement,
and the special levers mean that they're not so easy to interchange
with other components. But I can't now see any reason to prefer
old-style crossed lever centrepulls to cantilevers.

I haven't used sidepulls since my mid-70s Schwinn Continental was
stolen in 1976. As I recall they were Dia-Compes. What I recall
about them is that they stopped the bike fine. I've never seen weight
comparisons, which by rights ought to include all the relevant hardware
such as hangers, straddle wires, etc. Also, it's never seemed that
there were cantilevers of the same quality as a Campy, Dura Ace or
Superbe sidepull.

From a design perspective, it seems to me that (1) centerpulls are
much more complicated than either single- or dual-pivot sidepulls; and
(2) centerpulls are more prone to flex under the force of the rim
acting on the brake pads, mainly due to flex in the hanger with the
center bolt and pivots. I've never tried centerpulls mounted on
braze-ons, which might reduce or eliminate the flex problem. A number
of people seem to claim this is the case, including Tony Oliver, Jan
Heine and Grant Petersen. They've used 'em and I haven't, so at this
point I have to take their word for it.

V-brakes were created to benefit the mountain bike industry. The
issue was cable routing and simplifying basic setup, which created an
economies-of-scale cost savings for manufacturers like Giant,
Cannondale, Trek, etc. The need for a cable hanger was problematic
for rear suspension and, to a lesser extent, front suspension. Plus
they were new and different, and a less-than-astute bike magazine
industry mistakenly took V-brakes as a consumer-side improvement
rather than a supply-side improvement.

There may be some benefits for consumers, of course. It's harder to
set up V-brakes wrongly than is the case with cantilevers. The lever
feel is different because there is less friction loss with the longer
cable pull. The mechanical advantage is slightly higher, trading off
modulation for reduced hand grip. There are downsides, including very
close tolerances between the rim and the brake, which is a problem if
the wheel gets bent or a spoke breaks. And the pads are much thinner,
wearing out faster and needing to be replaced more often (also, the
thinner pads are much less compressible, which adds to the "power
brake" feeling of V-brakes; this is mistakenly perceived as "more
stopping power").

Every decent brake- whether sidepull, centerpull, cantilever, V-brake,
disc brake, drum brake, what have you- provides enough stopping power
to make the wheel skid. In that regard, none of these brakes provide
more stopping power than the others. The question of choice really
rests on other factors (lever feel, cable routing, clearance, etc).

(Gary Young) wrote in message . com...
Though I've been critical of Grant Peterson's effort to revive
centerpull brakes, I have to admit that the latest Rivendell Reader
(#30) gave me reasons to pause.

First of all, in the letters section, a reader (Thomas Papetti) points
out that
dual-pivot sidepulls won't track an out-of-true rim the way all other
brake types will. I'm not sure how much that counts in favor of
centerpulls (Papetti doesn't discuss them at all). Even though most
riders would probably use long-reach dual pivots in lieu of
centerpulls, long-reach single-pivot sidepulls and cantilevers are
still available if tracking is a significant worry.

Then in an article, Jan Heine makes several claims for the superiority
of sidepulls.

That should be "superiority of centerpulls."

He says, "The long lever on the cable side [above the pivot, if I
understand him correctly] and the short lever on the pad side [below
the pivot] gives centerpulls a huge mechanical advantage over
sidepulls. Just like a bolt-cutter, where long arms and short jaws
allow you to cut through thick steel bolts." Later on, he adds that
only with the advent of dual-pivot brakes did sidepulls catch up to
centerpulls in this respect.

That doesn't seem to jibe with Jobst's discussion in the FAQ, which
seems to suggest that single-pivot sidepulls and centerpulls had the
same mechanical advantage.

He argues that only the part of the arm below the pivot needs to be
beefy, because that's the only place where flex matters. "As a result,
the arms above the pivots can be incredibly skinny, as they don't need
to resist flex. That is where the weight savings of a centerpull
originate." He doesn't say what the weight savings is.

He writes, "And since the pivot on centerpull brakes is on the fork
leg, adding reach does not increase the flex or change the mechanical
advantage. So there is not incentive to go to short-reach brakes." I
think he means that since the distance between the pad and the pivot
point always remains the same, adding lever length above the pivot
doesn't effect the mechanical advantage. That sounds dubious to me --
doesn't changing the length of a cantilever brake's straddle cable
effect mechanical advantage even if all else remains the same?
Furthermore, from the photos of old centerpulls in the Reader, it
doesn't seem as if the distance from pivot to pad was always kept
constant (some long-reach brakes seem to achieve that reach in part by
increasing the lever below the pivot).

He notes that centerpulls don't stick out to the side like
centerpulls.

Should be "centerpulls don't stick out to the side like cantilevers."

It seems to me that that problem can be cured by using
v-brakes, though that introduces problems of its own (e.g., mating
them to road levers).

He says that even the standard-reach (what would be called long-reach
by most) dual-pivot brakes offered by Shimano don't leave much room
for fenders. Is that true? Just how big a tire would you have to run
before you would crowd out the dual pivots? (Elsewhere in the Reader,
Grant says that centerpulls will clear a 40mm tire or a 38mm tire with
fenders; what's the limit with the current long-reach dual pivots?)
Furthermore, why not long-reach single-pivots, which are still
available?

Probably his most controversial claim is that single-pivot sidepulls
"offered inferior performance" and became widespread mostly because of
Campagnolo's advertising and gruppo packaging. Contrast that with
Jobst's claim in the FAQ that, "The centerpull brake of the 1950's,
was popular for nearly a decade,
in spite of being entirely without merit, being worse in all respects
than the side pull brake with which it competed."

In the past, I've been pretty fed up with Grant's talk of reviving
centerpulls, because it so often appeared side-by-side with complaints
about Rivendell's financial straits and lack of popularity. I do
notice a more refreshing tone in this issue: he mentions a bike
planned for next year that will have braze-on pivots for centerpulls
and adds, "But we don't expect anybody to follow that lead., and we
fully expect to sell fewer bikes because of it. Centerpulls, for as
much sense as they make, will still scare off most customers."

Gary Young writes:

Though I've been critical of Grant Peterson's effort to revive
centerpull brakes, I have to admit that the latest Rivendell Reader
(#30) gave me reasons to pause.

I think two things should be noted about all brakes before the dual
pivot era, and that is they all had a 1:1 ratio in the "caliper" and a
4:1 ratio in the hand lever, all brakes being interchangeable under
any hand lever. This includes sidepull, centerpull and cantilever.

The second feature is that sidepull brakes have the pad pivot above
and only slightly (rim half width) offset from the braking surface so
that there is essentially no position change as the pad sweeps through
its wear life (cosine error). Centerpull and cantilever brakes
approach the rim at nearly a 45 degree angle and have large vertical
change throughout pad wear life, so much so that cantilever brakes
have dived under the rim leaving the bicycle with no brake at all.

The cantilever dives under but had the advantage of endless mud or
radial tire clearance, the centerpull goes into the tire as it wears
and offers no advantages whatsoever. I believe that is why it died so
quickly as it should have. It was sold on the premise that it had a
higher mechanical advantage, something that at first inspection it
appears to have through its long levers. They are twice as long as
the pad arms... but there are two of them, each receiving half the
force.

First of all, in the letters section, a reader (Thomas Papetti)
points out that dual-pivot sidepulls won't track an out-of-true rim
the way all other brake types will. I'm not sure how much that
counts in favor of centerpulls (Papetti doesn't discuss them at
all). Even though most riders would probably use long-reach dual
pivots in lieu of centerpulls, long-reach single-pivot sidepulls and
cantilevers are still available if tracking is a significant worry.

Then in an article, Jan Heine makes several claims for the
superiority of sidepulls.

He says, "The long lever on the cable side [above the pivot, if I
understand him correctly] and the short lever on the pad side [below
the pivot] gives centerpulls a huge mechanical advantage over
sidepulls. Just like a bolt-cutter, where long arms and short jaws
allow you to cut through thick steel bolts." Later on, he adds that
only with the advent of dual-pivot brakes did sidepulls catch up to
centerpulls in this respect.

That doesn't seem to jibe with Jobst's discussion in the FAQ, which
seems to suggest that single-pivot sidepulls and centerpulls had the
same mechanical advantage.

They had to have the same ME or you couldn't operate them with the
same pad clearance. The purpose of the dual pivot is to allow half
the pad clearance of former brakes and this required accurate
centering. This is necessary to offer the higher mechanical
advantage today's avocational riders need to stop their bicycles.

Just recall the story bicycle shops had to come up with to explain why
riders could not stop their Campagnolo Record equipped bicycles...
"These are racing brakes. Racers only need to modulate speed, not
stop." and the like. If you believe that you deserve to be led around
by the nose. The faster you go the harder you must brake. Descending
a mountain pass with straights and hairpin turns requires standing the
bicycle on its front wheel into every turn. This is done with two
fingers by racers using 4:1 brakes.

He argues that only the part of the arm below the pivot needs to be
beefy, because that's the only place where flex matters. "As a
result, the arms above the pivots can be incredibly skinny, as they
don't need to resist flex. That is where the weight savings of a
centerpull originate." He doesn't say what the weight savings is.

Flex in any part of the system eats up hand lever stroke. Who invents
this cock and bull stuff anyway? The lower arm must be stronger
because it is loaded in torsion from brake pad drag.

He writes, "And since the pivot on centerpull brakes is on the fork
leg, adding reach does not increase the flex or change the
mechanical advantage. So there is not incentive to go to
short-reach brakes." I think he means that since the distance
between the pad and the pivot point always remains the same, adding
lever length above the pivot doesn't effect the mechanical
advantage. That sounds dubious to me -- doesn't changing the length
of a cantilever brake's straddle cable effect mechanical advantage
even if all else remains the same? Furthermore, from the photos of
old centerpulls in the Reader, it doesn't seem as if the distance
from pivot to pad was always kept constant (some long-reach brakes
seem to achieve that reach in part by increasing the lever below the
pivot).

These are not people to be believed. They have no idea what they are
talking about and do it profusely. It reminds me of the kooks I see at
InterBike every year with a new crank mechanism that will make you go
faster, not to mention how much mechanism and weight it adds to the
bicycle.

He notes that centerpulls don't stick out to the side like
sidepulls. It seems to me that that problem can be cured by using
v-brakes, though that introduces problems of its own (e.g., mating
them to road levers).

How far??? What is the issue here anyway. Is it perhaps streamlining
or just someone who suffers from the "loose ends" syndrome (things
that protrude, as in toilet paper rolls that pay off the front instead
of the back [hidden ends])?

He says that even the standard-reach (what would be called
long-reach by most) dual-pivot brakes offered by Shimano don't leave
much room for fenders. Is that true?

NO.

Just how big a tire would you have to run before you would crowd out
the dual pivots? (Elsewhere in the Reader, Grant says that
centerpulls will clear a 40mm tire or a 38mm tire with fenders;
what's the limit with the current long-reach dual pivots?)
Furthermore, why not long-reach single-pivots, which are still
available?

Probably his most controversial claim is that single-pivot sidepulls
"offered inferior performance" and became widespread mostly because
of Campagnolo's advertising and gruppo packaging. Contrast that
with Jobst's claim in the FAQ that, "The centerpull brake of the
1950's, was popular for nearly a decade, in spite of being entirely
without merit, being worse in all respects than the side pull brake
with which it competed."

A conspiracy! The sidepull brake is the obvious mechanism for road
bicycles to all who understand mechanical design. All this other
stuff is amateur thinking guided by misunderstanding of the concept.
Even places like Campagnolo are not immune. After Tullio died the
place was run by incompetents who made the Delta brake, a non linear
response brake with huge cosine error. It was an Ide? fixe of someone
with "loose end" syndrome, externally clean but a mess inside.

http://draco.acs.uci.edu/rbfaq/FAQ/8f.15.html

In the past, I've been pretty fed up with Grant's talk of reviving
centerpulls, because it so often appeared side-by-side with complaints
about Rivendell's financial straits and lack of popularity. I do
notice a more refreshing tone in this issue: he mentions a bike
planned for next year that will have braze-on pivots for centerpulls
and adds, "But we don't expect anybody to follow that lead., and we
fully expect to sell fewer bikes because of it. Centerpulls, for as
much sense as they make, will still scare off most customers."

.... and they should. Now let's hear it again concisely. What are the
advantages?

Jobst Brandt

Tim McNamara writes:

Every decent brake- whether sidepull, centerpull, cantilever,
V-brake, disc brake, drum brake, what have you- provides enough
stopping power to make the wheel skid. In that regard, none of
these brakes provide more stopping power than the others. The
question of choice really rests on other factors (lever feel, cable
routing, clearance, etc).

That may be true today but for the older brakes, before dual pivot, it
was not. 4:1 leverage was more than a non athletic rider could
handle, especially with two fingers.

The different ratio hand levers caused problems for which people found
solutions. One of these was the Travel Agent, a clever and
appropriate name that we don't hear much about now that the dust has
settled.

http://tinyurl.com/r6la

Jobst Brandt

(Gary Young) writes:

In the past, I've been pretty fed up with Grant's talk of reviving
centerpulls, because it so often appeared side-by-side with complaints
about Rivendell's financial straits and lack of popularity. I do
notice a more refreshing tone in this issue: he mentions a bike
planned for next year that will have braze-on pivots for centerpulls
and adds, "But we don't expect anybody to follow that lead., and we
fully expect to sell fewer bikes because of it.

I have owned 2 bikes with centerpulls (raleigh grand prix, dawes
low-end), and 3 bikes with sidepulls (schwinn paramount, trek 500,
alan), and 1 bike with dual-pivot sidepulls (trek 2300) and one bike
with U-brakes (schwinn moab). I currently live on a very steep hill
in san diego, present. In terms of stopping power, this is where I
think that things stack up.

sidepulls (campy) - worst
dual-pivots (shimano) - better
centerpulls - best

U-brakes - hard to gauge since these are on a totally different kind
of (mountain) bike.

It is worth pointing out that when i recently got the Alan bike with
campy sidepulls, I immediately removed the campy pads and put new
low-end pads on it, since the campy pads weren't working. I then took
off the low end pads and bought premium oversized shimano pads, since
the low-end pads weren't working. the premium (ultegra) pads just
barely work. I am still very unhappy with the campy gran sport
sidepull performance, and I feel jeopardized every time i go down the
hill.

Campy and Shimano marketing hype aside, i think you can easily
determine the most powerful brakes by looking historically at what got
installed on tandem bicycles in the past. In the late 1960's and
1970's and 1980's, the choices were :

cantilevers - best
centerpulls - second best

no sidepulls installed on tandems.
even today, nobody puts dual-pivots on tandems.

i like the higher braking precision in centerpulls. The lever travel
is farther on centerpulls and so you know there is more mechanical
advantage. you can see it just by placing a set of weinmann levers
next to some campy levers.

that's all i need to know.

- Don Gillies
San Diego, CA

writes:

Tim McNamara writes:

Every decent brake- whether sidepull, centerpull, cantilever,
V-brake, disc brake, drum brake, what have you- provides enough
stopping power to make the wheel skid. In that regard, none of
these brakes provide more stopping power than the others. The
question of choice really rests on other factors (lever feel,
cable routing, clearance, etc).

That may be true today but for the older brakes, before dual pivot,
it was not. 4:1 leverage was more than a non athletic rider could
handle, especially with two fingers.

I'll concede that and excuse myself by admitting a limited point of
viewq. Having always been an "athletic" rider, I never have had
trouble with being able to squeeze any brake lever hard enough to make
the brake work. Being 6'4" and having commensurately sized hands, I
have tended to find brake lever bodies too small and uncomfortable
(only the 1998 and later Campy Ergo lever bodies feel really
comfortable to me).

Certainly my sidepulls with non-aero levers take more effort to use
than my dual pivot Campy Ergo brakes/levers. I don't remember what
the centerpull lever feel was like. I will agree that all brakes are
not equal from the practical, ergonomic perspective.

(Donald Gillies) writes:

I have owned 2 bikes with centerpulls (raleigh grand prix, dawes
low-end), and 3 bikes with sidepulls (schwinn paramount, trek 500,
alan), and 1 bike with dual-pivot sidepulls (trek 2300) and one bike
with U-brakes (schwinn moab). I currently live on a very steep hill
in san diego, present. In terms of stopping power, this is where I
think that things stack up.

sidepulls (campy) - worst
dual-pivots (shimano) - better
centerpulls - best

U-brakes - hard to gauge since these are on a totally different kind
of (mountain) bike.

Actually, U-brakes were just a new name for an old design"
centerpulls. Take a close look, they are just centerpull brakes with
a slightly different arm shape.

It is worth pointing out that when i recently got the Alan bike with
campy sidepulls, I immediately removed the campy pads and put new
low-end pads on it, since the campy pads weren't working. I then
took off the low end pads and bought premium oversized shimano pads,
since the low-end pads weren't working. the premium (ultegra) pads
just barely work. I am still very unhappy with the campy gran sport
sidepull performance, and I feel jeopardized every time i go down
the hill.

Try Mathauser or KoolStop Continental slamon colored pads. They work
better than any other pad on the market IMHO.

Tim McNamara wrote:

From a design perspective, it seems to me that (1) centerpulls are
much more complicated than either single- or dual-pivot sidepulls;

More so than single-pivot, less so than dual-pivot as the pivots are
symmetrical and there is no proportioning mechanism.

and (2) centerpulls are more prone to flex under the force of the rim
acting on the brake pads, mainly due to flex in the hanger with the
center bolt and pivots.

If you have developed such an impression, it was probably due to the
reach length of any centerpull brakes you have tried being well in
excess of whichever sidepull you were using for comparison.

Centerpulls locate the mechanical pivots, and their accompanying play,
further down the lever arm, for less effect on overall pad deflection
at the rim. The "bridge" element containing the pivot studs is
typically stouter than the analogous portion of sidepull arm.

I've never tried centerpulls mounted on
braze-ons, which might reduce or eliminate the flex problem. A number
of people seem to claim this is the case, including Tony Oliver, Jan
Heine and Grant Petersen. They've used 'em and I haven't, so at this
point I have to take their word for it.

Brazed-on pivots work. That is the definitive difference between the
road bike centerpull as used during the bike boom, and the U-brake as
used during the 80s MTB craze. The stopping power of a U-brake dwarfs
that of any road bike brake ever made, and U-brakes were no more
difficult to set up than a road caliper.

Brazing centerpull pivots to the frame usually reduces the overhung
length by more than half, and it usually anchors the brake to a
stiffer piece of the frame than a centerbolt does. What flex remains
can be attenuated by a booster plate, unlike flex that occurs at a
centerbolt.

Every decent brake- whether sidepull, centerpull, cantilever, V-brake,
disc brake, drum brake, what have you- provides enough stopping power
to make the wheel skid.

--in the rear, if you are a single lightweight rider on a
short-wheelbase upright bike without a heavy load. The incapacity of
the road caliper brake as furnished to provide more stopping power
when appropriate is its most serious shortcoming.

The ability of cantilever brakes, U-brakes (and other stud-mounted
centerpulls), v-brakes, and hydraulic rim brakes to be set up to
deliver more stopping power than most riders require is what makes
them versatile and valuable, even if it is of no benefit to most sport
riders.

Chalo Colina