Bike Stopping distances?

Bob who? said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

That sounds more like a rider test than a brake test. If you do
straight line, dry road, braking tests with a good rider, he can raise
the rear wheel with the front brake for most brakes. You'll need a
more subjective test than that.

Just recall that the best racing brake on the market was the Campagnolo
Record side pull brake, yet avocational riders complained about not
being able to stop adequately, mainly because they had insufficient
strength in the index and middle finger to , for instance, raise the
rear wheel off the road.

Bicycle shops used the excuse that these were racing brakes and racers
only need to control speed, not stop all the time. Well that is a big
dodge do avoid telling the customer he is a weakling. The faster a
vehicle goes (bicycle , Motorcycle, car, etc) the better the brakes
must be... for stopping.

Anyway, the response was not fast for these complainers because the
mechanical advantage of the 1:1 caliper and 4:1 hand lever could not
be increased without reducing pad clearance. Motor vehicle brakes run
with essentially no clearance, the pads dragging on the discs all the
time... besides which they all have power assist except for mini-cars
and motorcycles.

In order to increase the ME of the brake it had to have a guaranteed
pad retraction on both pads. Off center pads were n0o longer an
option with the 5.6:1 ratio common in brakes today and to achieve that
function, the dual pivot brake was required. Unfortunately it made a
step backward in that the left (front) caliper arm (the one on the off
center pivot) has large angular contact error so that as it wears it
sweeps upward into the tire.

The low pad clearance has caused problems in racing where riders on
climbs noted that while standing, the rear brake made scraping noises
in the wet, the place where grit invariably gets on the rim. To avoid
the dragging brake syndrome, riders opened the brake QR on ascents but
often failed to close it for the descent, thus realizing too late that
the bicycle had only one brake.

To get around that, Campagnolo went back to a center pivot brake in
the rear that has the old 4:1 ratio and large pad clearance. So there
you are, back in the old days again.

Jobst Brandt

See responses below:

cel

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Bob who? said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

That sounds more like a rider test than a brake test. If you do
straight line, dry road, braking tests with a good rider, he can raise
the rear wheel with the front brake for most brakes. You'll need a
more subjective test than that.

Just recall that the best racing brake on the market was the Campagnolo
Record side pull brake, yet avocational riders complained about not
being able to stop adequately, mainly because they had insufficient
strength in the index and middle finger to , for instance, raise the
rear wheel off the road.

Bicycle shops used the excuse that these were racing brakes and racers
only need to control speed, not stop all the time. Well that is a big
dodge do avoid telling the customer he is a weakling. The faster a
vehicle goes (bicycle , Motorcycle, car, etc) the better the brakes
must be... for stopping.

Not everyone has a strong grip. Some can benifit from a greater mechanical
advantage, even with the drawbacks as you have stated. Better to be able to
stop well with small clearances, than to have poor braking with a weak grip.

Quoted message said:

Anyway, the response was not fast for these complainers because the
mechanical advantage of the 1:1 caliper and 4:1 hand lever could not
be increased without reducing pad clearance. Motor vehicle brakes run
with essentially no clearance, the pads dragging on the discs all the
time... besides which they all have power assist except for mini-cars
and motorcycles.

In order to increase the ME of the brake it had to have a guaranteed
pad retraction on both pads. Off center pads were n0o longer an
option with the 5.6:1 ratio common in brakes today and to achieve that
function, the dual pivot brake was required.

Other solutions can be devised, such as longer lever arms on the cable
actuated side of the lever arms, or cam operation as with the Campy deltas,
or current Zero Gravities. As you have mentioned before progressive action
such as the Delta brakes should be avoided. However cam operation can be
made to have a low mechanical advantage until the brakes almost touch the
rims and then to have a constant high mechanical advantage. Athough this
design may be problematic for some to adjust correctely.

Unfortunately it made a

Quoted message said:

step backward in that the left (front) caliper arm (the one on the off
center pivot) has large angular contact error so that as it wears it
sweeps upward into the tire.

See above.

Quoted message said:

The low pad clearance has caused problems in racing where riders on
climbs noted that while standing, the rear brake made scraping noises
in the wet, the place where grit invariably gets on the rim. To avoid
the dragging brake syndrome, riders opened the brake QR on ascents but
often failed to close it for the descent, thus realizing too late that
the bicycle had only one brake.

To get around that, Campagnolo went back to a center pivot brake in
the rear that has the old 4:1 ratio and large pad clearance. So there
you are, back in the old days again.

Jobst Brandt

Bob said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

Thanks,

Hey Bob... here's the easy chart. No numbers, no doubt, no calculations...
just unadulterated collective experience.

Chart key:
Good enough means that stopping distance prevents you from hitting a car or
tree. Anything else means that stopping distance doesn't prevent you from
hitting the car or tree.

V-brakes - good enough
Dual-pivots - good enough
Centerpulls - good enough
Cantilevers - good enough
Single-pivots - ehh
U-brakes - bleah

Some specific Shimano brake pads - screech *bam!* rim blowout
Most others - good enough

Road tires - good enough unless turning
MTB tires - good enough unless turning
Crappy colored-tread tires - like riding glass on glass

Wet - good enough
Dry - good enough
Gravel - get up off the saddle
Sand - uh oh
Pond/River/Ocean - bail out quick

--
Phil, Squid-in-Training

anonymous snipes:

Quoted message said:

Quoted message said:

Quoted message said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

Quoted message said:

Quoted message said:

That sounds more like a rider test than a brake test. If you do
straight line, dry road, braking tests with a good rider, he can
raise the rear wheel with the front brake for most brakes. You'll
need a more subjective test than that.

Quoted message said:

Quoted message said:

Just recall that the best racing brake on the market was the
Campagnolo Record side pull brake, yet avocational riders
complained about not being able to stop adequately, mainly because
they had insufficient strength in the index and middle finger to ,
for instance, raise the rear wheel off the road.

Quoted message said:

Quoted message said:

Bicycle shops used the excuse that these were racing brakes and
racers only need to control speed, not stop all the time. Well
that is a big dodge do avoid telling the customer he is a weakling.
The faster a vehicle goes (bicycle , Motorcycle, car, etc) the
better the brakes must be... for stopping.

Quoted message said:

Not everyone has a strong grip. Some can benifit from a greater
mechanical advantage, even with the drawbacks as you have
stated. Better to be able to stop well with small clearances, than
to have poor braking with a weak grip.

That doesn't necessarily mean that all riders should be burdened with
the drawbacks of the dual pivot brake. These brakes cannot follow a
wobbly rim and jam if the wheel is out of true with, for instance one
broken spoke.

Quoted message said:

Quoted message said:

Anyway, the response was not fast for these complainers because the
mechanical advantage of the 1:1 caliper and 4:1 hand lever could
not be increased without reducing pad clearance. Motor vehicle
brakes run with essentially no clearance, the pads dragging on the
discs all the time... besides which they all have power assist
except for mini-cars and motorcycles.

Quoted message said:

Quoted message said:

In order to increase the ME of the brake it had to have a
guaranteed pad retraction on both pads. Off center pads were n0o
longer an option with the 5.6:1 ratio common in brakes today and to
achieve that function, the dual pivot brake was required.

Quoted message said:

Other solutions can be devised, such as longer lever arms on the
cable actuated side of the lever arms, or cam operation as with the
Campy deltas, or current Zero Gravities. As you have mentioned
before progressive action such as the Delta brakes should be
avoided. However cam operation can be made to have a low mechanical
advantage until the brakes almost touch the rims and then to have a
constant high mechanical advantage. Athough this design may be
problematic for some to adjust correctely.

That is not correct. The size of the human hand is the limit of
travel and that defines the stroke ratio of the mechanism. Variable
ratio brakes have been proven useless many times in the history of
brakes, both in motor vehicles and bicycles. The current brake levers
are well suited to hands but the resulting mechanical advantage, that
is easily altered in the caliper, is limited by the human hand to
brake clearance and lever ratio.

Quoted message said:

Quoted message said:

Unfortunately it made a step backward in that the left (front)
caliper arm (the one on the off center pivot) has large angular
contact error so that as it wears it sweeps upward into the tire.

Quoted message said:

See above.

I see nothing. Please explain. It took a long and well considered
development to arrive at the dual pivot design. It wasn't idly tossed
out there. If you think there is a simpler more useful way to make a
brake self centering, so that lower brake pad clearance is possible,
the bicycling industry would welcome the design.

Quoted message said:

Quoted message said:

The low pad clearance has caused problems in racing where riders on
climbs noted that while standing, the rear brake made scraping
noises in the wet, the place where grit invariably gets on the rim.
To avoid the dragging brake syndrome, riders opened the brake QR on
ascents but often failed to close it for the descent, thus
realizing too late that the bicycle had only one brake.

Quoted message said:

Quoted message said:

To get around that, Campagnolo went back to a center pivot brake in
the rear that has the old 4:1 ratio and large pad clearance. So
there you are, back in the old days again.

Jobst Brandt

See response below

Sorry, anonymous ~= less spam!

cel

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

anonymous snipes:

Quoted message said:

Quoted message said:

> Looking for a chart with bike stopping distances. Perhaps there's
> something out there where they compared brake types, pads, tires,
> etc - maybe even under wet and dry conditions?

Quoted message said:

Quoted message said:

That sounds more like a rider test than a brake test. If you do
straight line, dry road, braking tests with a good rider, he can
raise the rear wheel with the front brake for most brakes. You'll
need a more subjective test than that.

Quoted message said:

Quoted message said:

Just recall that the best racing brake on the market was the
Campagnolo Record side pull brake, yet avocational riders
complained about not being able to stop adequately, mainly because
they had insufficient strength in the index and middle finger to ,
for instance, raise the rear wheel off the road.

Quoted message said:

Quoted message said:

Bicycle shops used the excuse that these were racing brakes and
racers only need to control speed, not stop all the time. Well
that is a big dodge do avoid telling the customer he is a weakling.
The faster a vehicle goes (bicycle , Motorcycle, car, etc) the
better the brakes must be... for stopping.

Quoted message said:

Not everyone has a strong grip. Some can benifit from a greater
mechanical advantage, even with the drawbacks as you have
stated. Better to be able to stop well with small clearances, than
to have poor braking with a weak grip.

That doesn't necessarily mean that all riders should be burdened with
the drawbacks of the dual pivot brake. These brakes cannot follow a
wobbly rim and jam if the wheel is out of true with, for instance one
broken spoke.

Agreed. However the feeble and weak, or persons of small stature can may
find that dual pivots are a good tradeoff for them. They tend to be lighter
in mass and with properly built wheels with 36 spokes they will only have to
adjust their brake shoes to compensate for the poor arc of dual pivots. I
also find the old side pulls total adequate with the proper brake shoes and
clean rims. They would be the best choice for those with sufficient hand
strength. Single pivot side pulls are still available for those who want
them, athough the high quality ones tend to be used or old stock.

Quoted message said:

Quoted message said:

Quoted message said:

Anyway, the response was not fast for these complainers because the
mechanical advantage of the 1:1 caliper and 4:1 hand lever could
not be increased without reducing pad clearance. Motor vehicle
brakes run with essentially no clearance, the pads dragging on the
discs all the time... besides which they all have power assist
except for mini-cars and motorcycles.

Quoted message said:

Quoted message said:

In order to increase the ME of the brake it had to have a
guaranteed pad retraction on both pads. Off center pads were n0o
longer an option with the 5.6:1 ratio common in brakes today and to
achieve that function, the dual pivot brake was required.

Quoted message said:

Other solutions can be devised, such as longer lever arms on the
cable actuated side of the lever arms, or cam operation as with the
Campy deltas, or current Zero Gravities. As you have mentioned
before progressive action such as the Delta brakes should be
avoided. However cam operation can be made to have a low mechanical
advantage until the brakes almost touch the rims and then to have a
constant high mechanical advantage. Athough this design may be
problematic for some to adjust correctely.

That is not correct. The size of the human hand is the limit of
travel and that defines the stroke ratio of the mechanism. Variable
ratio brakes have been proven useless many times in the history of
brakes, both in motor vehicles and bicycles. The current brake levers
are well suited to hands but the resulting mechanical advantage, that
is easily altered in the caliper, is limited by the human hand to
brake clearance and lever ratio.

Quoted message said:

Quoted message said:

Unfortunately it made a step backward in that the left (front)
caliper arm (the one on the off center pivot) has large angular
contact error so that as it wears it sweeps upward into the tire.

Quoted message said:

See above.

I see nothing. Please explain. It took a long and well considered
development to arrive at the dual pivot design. It wasn't idly tossed
out there. If you think there is a simpler more useful way to make a
brake self centering, so that lower brake pad clearance is possible,
the bicycling industry would welcome the design.

It meat to point out that the Zero Gravity design does not have the drawback
of the short arc on one of the arms. It has a high ratio like a dual pivot,
thus suffers from the poor pad to rim clearance of the dual pivot brakes,
but with the familiar single pivot arc. The cam action appear to function in
a non-progressive way, but I have not measured this quantitatively. Only my
subjective observation. They do suffer from poor centering compared to side
or dual pivots though.

See diagram at:
http://www.competitivecyclist.com/za/CCY?PAGE=ZOOM&PRODUCT.ID=1230

Quoted message said:

Quoted message said:

Quoted message said:

The low pad clearance has caused problems in racing where riders on
climbs noted that while standing, the rear brake made scraping
noises in the wet, the place where grit invariably gets on the rim.
To avoid the dragging brake syndrome, riders opened the brake QR on
ascents but often failed to close it for the descent, thus
realizing too late that the bicycle had only one brake.

Quoted message said:

Quoted message said:

To get around that, Campagnolo went back to a center pivot brake in
the rear that has the old 4:1 ratio and large pad clearance. So
there you are, back in the old days again.

Jobst Brandt

Quoted message said:

See response below

Quoted message said:

Sorry, anonymous ~= less spam!

Quoted message said:

cel

You can put your name in there just don't give them your address. On
the other hand, I don't get piles of spam, maybe two or three a day now
and then and my address has been out there for years.

Quoted message said:

Quoted message said:

That doesn't necessarily mean that all riders should be burdened
with the drawbacks of the dual pivot brake. These brakes cannot
follow a wobbly rim and jam if the wheel is out of true with, for
instance one broken spoke.

Quoted message said:

Agreed. However the feeble and weak, or persons of small stature can
may find that dual pivots are a good tradeoff for them. They tend to
be lighter in mass and with properly built wheels with 36 spokes
they will only have to adjust their brake shoes to compensate for
the poor arc of dual pivots. I also find the old side pulls total
adequate with the proper brake shoes and clean rims. They would be
the best choice for those with sufficient hand strength. Single
pivot side pulls are still available for those who want them,
although the high quality ones tend to be used or old stock.

As I said, that shouldn't mean that other brakes are no longer being
made, just because some riders have a weaker grip.

Quoted message said:

Quoted message said:

Quoted message said:

> Anyway, the response was not fast for these complainers because
> the mechanical advantage of the 1:1 caliper and 4:1 hand lever
> could not be increased without reducing pad clearance. Motor
> vehicle brakes run with essentially no clearance, the pads
> dragging on the discs all the time... besides which they all
> have power assist except for mini-cars and motorcycles.

Quoted message said:

Quoted message said:

Quoted message said:

> In order to increase the ME of the brake it had to have a
> guaranteed pad retraction on both pads. Off center pads were n0o
> longer an option with the 5.6:1 ratio common in brakes today and
> to achieve that function, the dual pivot brake was required.

Quoted message said:

Quoted message said:

Quoted message said:

Other solutions can be devised, such as longer lever arms on the
cable actuated side of the lever arms, or cam operation as with the
Campy deltas, or current Zero Gravities. As you have mentioned
before progressive action such as the Delta brakes should be
avoided. However cam operation can be made to have a low mechanical
advantage until the brakes almost touch the rims and then to have a
constant high mechanical advantage. Although this design may be
problematic for some to adjust correctly.

Quoted message said:

Quoted message said:

That is not correct. The size of the human hand is the limit of
travel and that defines the stroke ratio of the mechanism.
Variable ratio brakes have been proven useless many times in the
history of brakes, both in motor vehicles and bicycles. The
current brake levers are well suited to hands but the resulting
mechanical advantage, that is easily altered in the caliper, is
limited by the human hand to brake clearance and lever ratio.

Quoted message said:

Quoted message said:

Quoted message said:

> Unfortunately it made a step backward in that the left (front)
> caliper arm (the one on the off center pivot) has large angular
> contact error so that as it wears it sweeps upward into the tire.

Quoted message said:

Quoted message said:

Quoted message said:

See above.

Quoted message said:

Quoted message said:

I see nothing. Please explain. It took a long and well considered
development to arrive at the dual pivot design. It wasn't idly
tossed out there. If you think there is a simpler more useful way
to make a brake self centering, so that lower brake pad clearance
is possible, the bicycling industry would welcome the design.

Quoted message said:

It meat to point out that the Zero Gravity design does not have the
drawback of the short arc on one of the arms. It has a high ratio
like a dual pivot, thus suffers from the poor pad to rim clearance
of the dual pivot brakes, but with the familiar single pivot
arc. The cam action appear to function in a non-progressive way, but
I have not measured this quantitatively. Only my subjective
observation. They do suffer from poor centering compared to side or
dual pivots though.

Quoted message said:

See diagram at:
http://www.competitivecyclist.com/za/CCY?PAGE=ZOOM&PRODUCT.ID=1230

A more useful picture is at:

http://tinyurl.com/bsgq5

where the cam is visible and the reason this brake can probably get by
without two pivots. Conspicuous is the return spring that doesn't
have external elephant ears that nearly all springs on caliper brakes
have. Those elephant ears are the center of rotation of the spring
ends and that causes sliding against the brake arm. This brake has
the coil concentric with the pivot bolt and has no sliding motion at
the contacts at the ends of the spring.

It is the sliding motion in a dirty environment that makes single
pivot brakes go off center. Apparently the designer of this brake was
aware of that and used a spring that will not cause off-center brake
pads. I made such a design for Campagnolo calipers but never got any
springs manufactured. With a bit of cleaning now and then, my brakes
work well enough to not warrant this exercise in spring winding
although it might be a nice retrofit that I'm sure others would like.

So the big question is: why do so many web-sites have pictures of the
front of the brake instead of a view that shows how it works? They
seem to love a mystery.

Jobst Brandt

Bob said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

Too many varibles would be present to represent this in any meaningful
way. Tire grip, rider weight, height and posture, and road surface
conditions and grade all have a bearing on stopping distance. Decent
brakes will allow almost any rider to brake hard enough to cause the
rear wheel to lift; overly hard braking can induce a face plant,
particularly for a tall rider with an erect posture. The bike's brake
system, in fact, is usually not the limiting factor in my experience;
the rider's height and posture has at least as much bearing on
stopping distance.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
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Squid-in-Training said:

Wet - good enough
Dry - good enough
Gravel - get up off the saddle
Sand - uh oh
Pond/River/Ocean - bail out quick

Add:

Leaves: Expect to slide...lots.

"Wet" can have variable results; the first dampening of a road that
has been dry for a while may produce a lubricant film that renders al
other considerations moot.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Where's the hatrack said:

Quoted message said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

Quoted message said:

Too many varibles would be present to represent this in any
meaningful way. Tire grip, rider weight, height and posture, and
road surface conditions and grade all have a bearing on stopping
distance. Decent brakes will allow almost any rider to brake hard
enough to cause the rear wheel to lift; overly hard braking can
induce a face plant, particularly for a tall rider with an erect
posture. The bike's brake system, in fact, is usually not the
limiting factor in my experience; the rider's height and posture has
at least as much bearing on stopping distance.

"rider height and posture has at least as much bearing on stopping
distance." and tires or road surface is a dodge. For any given test
rider a comparative chart could be made holding those parameters
constant. The main feature of a brake is the ease with which a rider
can control speed for cornering and stopping, and that is harder to
assess without some subjective evaluation by the tester. Stopping
distance is not the main concern with bicycle brakes because with a
capable rider, most brakes can raise the rear wheel in a straight line
stop given a strong hand on the lever.

As a great example, the Campagnolo Delta brake had good stopping power
but was ultimately scrapped because it had poor modulation, having a
non-linear mechanical advantage that increased steeply as pads wore.

Jobst Brandt

On Tue, 20 Sep 2005 15:50:49 GMT, [email hidden]

Quoted message said:

Where's the hatrack said:

Quoted message said:

Looking for a chart with bike stopping distances. Perhaps there's
something out there where they compared brake types, pads, tires,
etc - maybe even under wet and dry conditions?

Quoted message said:

Too many varibles would be present to represent this in any
meaningful way. Tire grip, rider weight, height and posture, and
road surface conditions and grade all have a bearing on stopping
distance. Decent brakes will allow almost any rider to brake hard
enough to cause the rear wheel to lift; overly hard braking can
induce a face plant, particularly for a tall rider with an erect
posture. The bike's brake system, in fact, is usually not the
limiting factor in my experience; the rider's height and posture has
at least as much bearing on stopping distance.

..."rider height and posture has at least as much bearing on stopping
distance." and tires or road surface is a dodge. [snip] Stopping
distance is not the main concern with bicycle brakes because with a
capable rider, most brakes can raise the rear wheel in a straight line
stop given a strong hand on the lever.

True, but...

The question was about the actual stopping distances that would be
obtained, and my point is that this is a flexible number with
mechanical, local and biological components which make test numbers
less than useful as a predictor of real-world results. The bike's
capabilities can, as you correctly state, be safely assumed to be in
excess of what is required to produce the minimum stopping distance
for given conditions, but the rider's actions and abilities are an
unknown which is hard to quantify.

As a starting point, in my direct experience, not all riders (myself
included) are given to habitually using a either a constant posture or
one that keeps the center of mass as low as practical, and one does
not always have the option of changing posture to get the center of
mass down during an emergency stop. If the center of mass is high,
the available braking effort without spilling will be lower than if
the cm was better located relative to the contact patch. I have
encountered a number of oh-[censored] situations in which I ended up either
stopping longer than I preferred or going down because I couldn't get
low fast enough while applying the brakes. (Fortunately for me, I
don't ride so aggressively that these resulted in major
calamities...but a less cautious rider might have had different
results.)

Add to this the fact that many bikes come with brakes that require
relatively little hand effort to lock the front wheel, and the issue
becomes even less predictable; in an emergency, a common reaction is
to grab for the brakes overly hard; this is more likely to result in a
spill than to produce a minimum-distance controlled stop in my
opinion.

My point, therefore, is that in the scope of common on-street riding,
the limiting factor in a given situation will more often be the
rider's habits and the local conditions rather than the braking
ability of the bike. The brakes will, as you say, almost always have
more capability than can be used...but if the center of mass is at too
great an angle to the front contact patch, or if the rider is
underskilled in the use of the brakes, the deceleration capability for
the system as a whole may be below what is needed at the moment though
the available stopping distance may have been adequate if the rider
was tucked and practised. (This assumes that gravel, leaves, oily
surfaces and the like are not present as compliications.)

Although this might seem like a strong argument in favor of developing
better riding posture and skills, a demonstration of the fact that
such advice will not always either be heeded or prove useful was
provided this morning. On the way to dropping my daughter off at
school, I saw a rider take a dive about a block in front of me when he
applied the brakes hard to avoid a car that had backed out in front of
him across the bike lane. He was not particularly erect on the saddle,
but his center of mass was artificially high due to the presence of a
backpack full of books. When he went for the brakes at what I would
guess was about 12 to 14 mph, he applied them a bit too hard for the
conditions, lifted the rear wheel a bit much, and went down at an
angle. Luckily for him, he was essentially uninjured. The driver of
the vehicle may not have even realized that he'd caused the rider to
spill; he drove off without looking back. The rider and bike landed
about ten feet short of the driveway that the car emerged from. The
street has some trees along it, but the car's driver should have been
able to see the bike approaching. I'm guessing that he glanced once,
and then backed out without checking again.

Brake system capabilities aren't the issue, IMO. It's the rider and
the conditions that will determine the stopping distance...and that
distance may not be short enough to avoid a collision even when it's
as short as could be reasonably achieved.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

Quoted message said:

The low pad clearance [dual pivot brakes] has caused problems in racing where riders on
climbs noted that while standing, the rear brake made scraping noises
in the wet, the place where grit invariably gets on the rim. To avoid
the dragging brake syndrome, riders opened the brake QR on ascents but
often failed to close it for the descent, thus realizing too late that
the bicycle had only one brake.

To get around that, Campagnolo went back to a center pivot brake in
the rear that has the old 4:1 ratio and large pad clearance. So there
you are, back in the old days again.

Is this willful misinformation?

As far back as 1987, Campy was making detented sliding pin QRs mounted
in brake levers/bodies. These don't cause brake power loss when left
"open" as do caliper-mounted cam-style QRs, since there is no change in
cable length (cam QRs) or pivot points.

Maybe I missed an early iteration, but if all the dual pivot Campagnolo
brakes had this kind of QR (as do my older C Record "convertibles" and
a couple of sets of newer Chorus D brakes), when/how would a
Campy-equipped rider lose braking power by forgetting to click his pins
back "in" to "closed" position? The worst possible, you miss your first
grab at the lever because it opens a little further with the QR open.
But the brakes are there. No problem, no correction needed.

No, with the pin-style QRs for DP and centerpull calipers alike, we are
not "back in the old days" because Campy "D" brakes did not go back to
the inferior cam QR for the rear brake. --D-y

Where's the hatrack said:

Although this might seem like a strong argument in favor of
developing better riding posture and skills, a demonstration of the
fact that such advice will not always either be heeded or prove
useful was provided this morning. On the way to dropping my
daughter off at school, I saw a rider take a dive about a block in
front of me when he applied the brakes hard to avoid a car that had
backed out in front of him across the bike lane. He was not
particularly erect on the saddle, but his center of mass was
artificially high due to the presence of a backpack full of books.

Quoted message said:

When he went for the brakes at what I would guess was about 12 to 14
mph, he applied them a bit too hard for the conditions, lifted the
rear wheel a bit much, and went down at an angle. Luckily for him,
he was essentially uninjured. The driver of the vehicle may not
have even realized that he'd caused the rider to spill; he drove off
without looking back. The rider and bike landed about ten feet
short of the driveway that the car emerged from. The street has
some trees along it, but the car's driver should have been able to
see the bike approaching. I'm guessing that he glanced once, and
then backed out without checking again.

I doubt that the sequence of events went as you surmise. He most
likely "went over the bars" for the same reason most (aka overwhelming
majority) such incidents occur; that being that the bicycle overturned
when his legs hit the handlebars. This is the cause of nearly all
such endos. Riders who do this generally cannot, in normal posture
(bracing arms), raise the rear wheel by braking if they were to try.

http://www.sheldonbrown.com/brandt/over-the-bars.html

Quoted message said:

Brake system capabilities aren't the issue, IMO. It's the rider and
the conditions that will determine the stopping distance...and that
distance may not be short enough to avoid a collision even when it's
as short as could be reasonably achieved.

I, for one, do not like the effect of water on the rim, be that with
rain, or worse, with snow on the rim inner circumference. The snow
effect is worse, because with snow, braking does not come back until
all the snow is melted. It makes clear that even in rain, rim brakes
only work where there is partial dryness, other wise it's like a razor
gliding effortlessly over the skin. Because there is so little
braking on a wet rim, the snow is not readily melted so it takes far
longer than one expects. It's times like these when disc brakes start
looking like a solution. Fortunately, this doesn't occur often enough
to warrant the change.

Jobst Brandt

Quoted message said:

here on planet xenon,

That explains a lot.

--
Phil, Squid-in-Training

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Where's the hatrack said:

Although this might seem like a strong argument in favor of
developing better riding posture and skills, a demonstration

of the

Quoted message said:

Quoted message said:

fact that such advice will not always either be heeded or

prove

Quoted message said:

Quoted message said:

useful was provided this morning. On the way to dropping my
daughter off at school, I saw a rider take a dive about a

block in

Quoted message said:

Quoted message said:

front of me when he applied the brakes hard to avoid a car

that had

Quoted message said:

Quoted message said:

backed out in front of him across the bike lane. He was not
particularly erect on the saddle, but his center of mass was
artificially high due to the presence of a backpack full of

books.

Quoted message said:

Quoted message said:

When he went for the brakes at what I would guess was about

12 to 14

Quoted message said:

Quoted message said:

mph, he applied them a bit too hard for the conditions,

lifted the

Quoted message said:

Quoted message said:

rear wheel a bit much, and went down at an angle. Luckily

for him,

Quoted message said:

Quoted message said:

he was essentially uninjured. The driver of the vehicle may

not

Quoted message said:

Quoted message said:

have even realized that he'd caused the rider to spill; he

drove off

Quoted message said:

Quoted message said:

without looking back. The rider and bike landed about ten

feet

Quoted message said:

Quoted message said:

short of the driveway that the car emerged from. The street

has

Quoted message said:

Quoted message said:

some trees along it, but the car's driver should have been

able to

Quoted message said:

Quoted message said:

see the bike approaching. I'm guessing that he glanced once,

and

Quoted message said:

Quoted message said:

then backed out without checking again.

I doubt that the sequence of events went as you surmise. He

most

Quoted message said:

likely "went over the bars" for the same reason most (aka

overwhelming

Quoted message said:

majority) such incidents occur; that being that the bicycle

overturned

Quoted message said:

when his legs hit the handlebars. This is the cause of nearly

all

Quoted message said:

such endos. Riders who do this generally cannot, in normal

posture

Quoted message said:

(bracing arms), raise the rear wheel by braking if they were to

try.

Quoted message said:

http://www.sheldonbrown.com/brandt/over-the-bars.html

Quoted message said:

Brake system capabilities aren't the issue, IMO. It's the

rider and

Quoted message said:

Quoted message said:

the conditions that will determine the stopping

distance...and that

Quoted message said:

Quoted message said:

distance may not be short enough to avoid a collision even

when it's

Quoted message said:

Quoted message said:

as short as could be reasonably achieved.

I, for one, do not like the effect of water on the rim, be that

with

Quoted message said:

rain, or worse, with snow on the rim inner circumference. The

snow

Quoted message said:

effect is worse, because with snow, braking does not come back

until

Quoted message said:

all the snow is melted. It makes clear that even in rain, rim

brakes

Quoted message said:

only work where there is partial dryness, other wise it's like

a razor

Quoted message said:

gliding effortlessly over the skin. Because there is so little
braking on a wet rim, the snow is not readily melted so it

takes far

Quoted message said:

longer than one expects. It's times like these when disc

brakes start

Quoted message said:

looking like a solution. Fortunately, this doesn't occur often

enough

Quoted message said:

to warrant the change.

I have literally been unable to stop (without dragging a foot)
while descending in the rain with some mid-90s cantilevers
coupled with STI levers. The mechanical advantage mis-match was
a real problem that took a lot of fiddling to remedy. The Salmon
KoolStops make most competent single and dual pivot brakes
passable in the rain.

For me, braking in the rain takes a distant back seat to
traction. I crashed twice a couple weeks ago while riding in the
rain, the second time on a steep descent. I managed to break a
couple ribs (let me tell you, that hurts like hell). My front
wheel washed out -- an Avocet 25mm Carbon 12 tire that I had
retired from another bike because I thought it was slippery. I
wonder if Avocet has changed its compound. They just do not seem
to stick as well as they used to. -- Jay Beattie.

Sorry about your crash, but if you thought the tire was too slippery way did
you then ride it in the rain? I also wonder if the Avocet compound has been
changed now. Maybe they followed other companies and added silica to the
rubber. Silica reputed to be bad in the rain.

cel

"Jay Beattie" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Where's the hatrack said:

Although this might seem like a strong argument in favor of
developing better riding posture and skills, a demonstration

of the

Quoted message said:

Quoted message said:

fact that such advice will not always either be heeded or

prove

Quoted message said:

Quoted message said:

useful was provided this morning. On the way to dropping my
daughter off at school, I saw a rider take a dive about a

block in

Quoted message said:

Quoted message said:

front of me when he applied the brakes hard to avoid a car

that had

Quoted message said:

Quoted message said:

backed out in front of him across the bike lane. He was not
particularly erect on the saddle, but his center of mass was
artificially high due to the presence of a backpack full of

books.

Quoted message said:

Quoted message said:

When he went for the brakes at what I would guess was about

12 to 14

Quoted message said:

Quoted message said:

mph, he applied them a bit too hard for the conditions,

lifted the

Quoted message said:

Quoted message said:

rear wheel a bit much, and went down at an angle. Luckily

for him,

Quoted message said:

Quoted message said:

he was essentially uninjured. The driver of the vehicle may

not

Quoted message said:

Quoted message said:

have even realized that he'd caused the rider to spill; he

drove off

Quoted message said:

Quoted message said:

without looking back. The rider and bike landed about ten

feet

Quoted message said:

Quoted message said:

short of the driveway that the car emerged from. The street

has

Quoted message said:

Quoted message said:

some trees along it, but the car's driver should have been

able to

Quoted message said:

Quoted message said:

see the bike approaching. I'm guessing that he glanced once,

and

Quoted message said:

Quoted message said:

then backed out without checking again.

I doubt that the sequence of events went as you surmise. He

most

Quoted message said:

likely "went over the bars" for the same reason most (aka

overwhelming

Quoted message said:

majority) such incidents occur; that being that the bicycle

overturned

Quoted message said:

when his legs hit the handlebars. This is the cause of nearly

all

Quoted message said:

such endos. Riders who do this generally cannot, in normal

posture

Quoted message said:

(bracing arms), raise the rear wheel by braking if they were to

try.

Quoted message said:

http://www.sheldonbrown.com/brandt/over-the-bars.html

Quoted message said:

Brake system capabilities aren't the issue, IMO. It's the

rider and

Quoted message said:

Quoted message said:

the conditions that will determine the stopping

distance...and that

Quoted message said:

Quoted message said:

distance may not be short enough to avoid a collision even

when it's

Quoted message said:

Quoted message said:

as short as could be reasonably achieved.

I, for one, do not like the effect of water on the rim, be that

with

Quoted message said:

rain, or worse, with snow on the rim inner circumference. The

snow

Quoted message said:

effect is worse, because with snow, braking does not come back

until

Quoted message said:

all the snow is melted. It makes clear that even in rain, rim

brakes

Quoted message said:

only work where there is partial dryness, other wise it's like

a razor

Quoted message said:

gliding effortlessly over the skin. Because there is so little
braking on a wet rim, the snow is not readily melted so it

takes far

Quoted message said:

longer than one expects. It's times like these when disc

brakes start

Quoted message said:

looking like a solution. Fortunately, this doesn't occur often

enough

Quoted message said:

to warrant the change.

I have literally been unable to stop (without dragging a foot)
while descending in the rain with some mid-90s cantilevers
coupled with STI levers. The mechanical advantage mis-match was
a real problem that took a lot of fiddling to remedy. The Salmon
KoolStops make most competent single and dual pivot brakes
passable in the rain.

For me, braking in the rain takes a distant back seat to
traction. I crashed twice a couple weeks ago while riding in the
rain, the second time on a steep descent. I managed to break a
couple ribs (let me tell you, that hurts like hell). My front
wheel washed out -- an Avocet 25mm Carbon 12 tire that I had
retired from another bike because I thought it was slippery. I
wonder if Avocet has changed its compound. They just do not seem
to stick as well as they used to. -- Jay Beattie.

Quoted message said:

Sorry about your crash, but if you thought the tire was too slippery way did
you then ride it in the rain? I also wonder if the Avocet compound has been
changed now. Maybe they followed other companies and added silica to the
rubber. Silica reputed to be bad in the rain.

there's no reason for silica compunds to be bad in the rain. michelins
certainly aren't, but they use a dual compound solution to make sure.
carbon compounds can be tuned for rolling resistance /or/ grip, not
both. silica /can/ be tuned for both, hence its increasing use in both
bike & automotive apps.

Quoted message said:

cel

"Jay Beattie" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

<[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Where's the hatrack writes:

>Although this might seem like a strong argument in favor of
>developing better riding posture and skills, a demonstration

of the

Quoted message said:

>fact that such advice will not always either be heeded or

prove

Quoted message said:

>useful was provided this morning. On the way to dropping my
>daughter off at school, I saw a rider take a dive about a

block in

Quoted message said:

>front of me when he applied the brakes hard to avoid a car

that had

Quoted message said:

>backed out in front of him across the bike lane. He was not
>particularly erect on the saddle, but his center of mass was
>artificially high due to the presence of a backpack full of

books.

Quoted message said:

>When he went for the brakes at what I would guess was about

12 to 14

Quoted message said:

>mph, he applied them a bit too hard for the conditions,

lifted the

Quoted message said:

>rear wheel a bit much, and went down at an angle. Luckily

for him,

Quoted message said:

>he was essentially uninjured. The driver of the vehicle may

not

Quoted message said:

>have even realized that he'd caused the rider to spill; he

drove off

Quoted message said:

>without looking back. The rider and bike landed about ten

feet

Quoted message said:

>short of the driveway that the car emerged from. The street

has

Quoted message said:

>some trees along it, but the car's driver should have been

able to

Quoted message said:

>see the bike approaching. I'm guessing that he glanced once,

and

Quoted message said:

>then backed out without checking again.

I doubt that the sequence of events went as you surmise. He

most

Quoted message said:

likely "went over the bars" for the same reason most (aka

overwhelming

Quoted message said:

majority) such incidents occur; that being that the bicycle

overturned

Quoted message said:

when his legs hit the handlebars. This is the cause of nearly

all

Quoted message said:

such endos. Riders who do this generally cannot, in normal

posture

Quoted message said:

(bracing arms), raise the rear wheel by braking if they were to

try.

Quoted message said:

http://www.sheldonbrown.com/brandt/over-the-bars.html

>Brake system capabilities aren't the issue, IMO. It's the

rider and

Quoted message said:

>the conditions that will determine the stopping

distance...and that

Quoted message said:

>distance may not be short enough to avoid a collision even

when it's

Quoted message said:

>as short as could be reasonably achieved.

I, for one, do not like the effect of water on the rim, be that

with

Quoted message said:

rain, or worse, with snow on the rim inner circumference. The

snow

Quoted message said:

effect is worse, because with snow, braking does not come back

until

Quoted message said:

all the snow is melted. It makes clear that even in rain, rim

brakes

Quoted message said:

only work where there is partial dryness, other wise it's like

a razor

Quoted message said:

gliding effortlessly over the skin. Because there is so little
braking on a wet rim, the snow is not readily melted so it

takes far

Quoted message said:

longer than one expects. It's times like these when disc

brakes start

Quoted message said:

looking like a solution. Fortunately, this doesn't occur often

enough

Quoted message said:

to warrant the change.

I have literally been unable to stop (without dragging a foot)
while descending in the rain with some mid-90s cantilevers
coupled with STI levers. The mechanical advantage mis-match was
a real problem that took a lot of fiddling to remedy. The Salmon
KoolStops make most competent single and dual pivot brakes
passable in the rain.

For me, braking in the rain takes a distant back seat to
traction. I crashed twice a couple weeks ago while riding in the
rain, the second time on a steep descent. I managed to break a
couple ribs (let me tell you, that hurts like hell). My front
wheel washed out -- an Avocet 25mm Carbon 12 tire that I had
retired from another bike because I thought it was slippery. I
wonder if Avocet has changed its compound. They just do not seem
to stick as well as they used to. -- Jay Beattie.

Quoted message said:

anonymous snipes again:

(earlier; him, then me):

Quoted message said:

Quoted message said:

Quoted message said:

anonymous snipes:

Quoted message said:

Snipe? Wow, from the pro. Thanks!

(JB):

Quoted message said:

Main Entry: snipe
Function: intransitive verb
Inflected Form(s): sniped; sniping

1 : to shoot at exposed individuals (as of an enemy's forces) from a
usually concealed point of vantage

I think that describes your rude and anonymous style accurately.

Likewise, to the nth degree. Except for the anonymous part, of course.
Which continues.

Recent example, Jobstsnipe:

(JB wrote):

Quoted message said:

Quoted message said:

Quoted message said:

Oh?

snipe #1

Quoted message said:

Quoted message said:

Quoted message said:

And you believe these riders could have used such brake levers

Snipe #2

Quoted message said:

Quoted message said:

Quoted message said:

and that Campagnolo recently came up with this single pivot rear
brake so that we can have two kinds of calipers gratuitously.

Snipe #3.

Feigning surprise, assigning ideas not stated, twice. AKA "putting
words in someone's mouth".

No, Jobst I was pointing out that Campy (as I said) has been making
some form of the sliding pin QR for close to twenty years. Have you
been posting about Campy users losing brake power by forgetting to
"close" these lever-mounted QRs for the same length of time? I have
seen you repeat this erroneous idea two or three times recently.

One more time: If a Campy dual pivot user forgets to close his rear QR
after opening it to reduce/eliminate rim rub on brake blocks during
climbing, braking power is not lost, as with cam-style QRs. So Campy
did not have to come up with a different design to solve the problem of
losing brake power if the pin-style QR is left open. That's the point,
right there.

(Anon., or "me"😉:

Quoted message said:

Quoted message said:

However, I use "real" sized, correctly
labeled 23mm tires, no problem with wheel changes on the front.

(JB, stepping):

Quoted message said:

I don't see how that helps people who ride other sizes of tires and
need a QR on the brakes to make a wheel change. Please explain how
that would work for such riders.

They'll just have to help themselves, I guess <g>. And be careful to
always, always close their cammy QRs, of course.

(the rattatat of a keyboard, sounding much like my own, firing from
behind the stone wall at the brave Redcoats, or was that a Hessian?):

Quoted message said:

Quoted message said:

[front wheel change, Campy DP brake]Pops right out of there, I do it > >all the time. I don't need to run
the (front) DP pads right up against the rim, and there's plenty of
brake power for my use here in the hills of Austin. If I were in
the mountains, maybe I'd use the front adjuster, just as I've done,
from need, with a centerpull brake.

(JB)

Quoted message said:

Yes, go on. How does this address the problems I mentioned?

Which problem? There are more now... First, people with pin QRs were
losing brakes, then other people couldn't get their tires in and out...

Quoted message said:

I think I responded to a non responding thread. This is not making
progress.

I've responded at least twice now. Progress? For my use, Campy DP's are
progress beyond the N.Record and the like, both for stopping power and
safety/ease of use of the QR. Yes, and a QR easily operational from the
handlebar; I've seen you condemn brifters as "too easy", so I imagine
this is another fault of the modern Campy QR from your viewpoint.

However, if "progress" is "agree with Jobst", no, you're not doing well
at all. I use 9sp, too-- all of them, even the crossovers on occasion.
Your saying that I don't need all those gears doesn't make it true,
even if you can ride your bicycle faster than I can ride mine. Get it?

"What about those whose tires are too big"... I just remembered
borrowing a Vittoria 25mm-shod front wheel. No problem, in/out with
that one, either. I'm not a light rider, but I think I could probably
ride dirt roads "no problem" on that bomber. "Please tell me, how huge
a tire must we employ in order to further condemn the Campagnolo Dual
Pivot brake?"
--D.u.s.t.o.y.e.v.s.k.y

Quoted message said:

This type of brake QR has the problem that it has too short a throw to
open the pads sufficiently to allow easy wheel changes. When that is
added to the higher mechanical advantage of the dual pivot brake you
have no QR, just a little more pad clearance.

But a little more pad clearance is all that is needed for the
brakes-dragging-on-standing-climbs thing, which you were talking about.
Brakes dragging on flexy climb? Open lever QR. Change wheel? Open caliper
QR. Where's the problem?

Jasper

"jim beam" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Sorry about your crash, but if you thought the tire was too

slippery way did

Quoted message said:

Quoted message said:

you then ride it in the rain? I also wonder if the Avocet

compound has been

Quoted message said:

Quoted message said:

changed now. Maybe they followed other companies and added

silica to the

Quoted message said:

Quoted message said:

rubber. Silica reputed to be bad in the rain.

there's no reason for silica compunds to be bad in the rain.

michelins

Quoted message said:

certainly aren't, but they use a dual compound solution to make

sure.

Quoted message said:

carbon compounds can be tuned for rolling resistance /or/ grip,

not

Quoted message said:

both. silica /can/ be tuned for both, hence its increasing use

in both

Quoted message said:

bike & automotive apps.

Honestly, I had forgotten why I shifted that tire from one bike
to the other -- until after the crash. And it was not that bad
of a tire -- it just was not as good as the tires on my regular
rain bike, which was out of commission due to a broken brake
bridge.

I doubt Avocet has started adding silica, being that the tire is
named the Carbon 12 -- although they may have changed other
constituents of the compound which may affect traction, like
percentages of natural and synthetic rubber, resins, etc.
Carbon based compounds do tend to give better traction in the
rain, IMO, but there are some excellent soft compound silica
based tires out there that do just as well or better. Finally,
to be fair, I have no way of knowing whether this fall was some
weird fluke or whether it was due to preventable slip-out. My
real point is that slip out and traction are, for me, much more
real concerns than slightly reduced braking in the rain. Indeed,
my regular rain bike has nearly 30 year old single pivot Campy NR
brakes, and they worked fine. -- Jay Beattie.