Unnerving braking experiences; sudden braking increase.

Ben C wrote:

ddog wrote:

The Adult ego state is the only ego state that does not utilize
psychological games, whichoften involve 'Tragic life scripts'; and
is purely intellectual like Spock on Star Trek.You're right that
people's ego states sometimes turn threads into Tragic Life
Scripts.

But it's not all bad. You and I are motivated only by the pursuit of
total logic, but sometimes it's people's egotistical desire to prove
each other wrong at all costs that's what drives them to spend the
effort to write clear and well-researched posts.

Hmm. Perhaps y'all could spin this thread off to alt.crackpot-
notions.psychological?

Chalo

On Sat, 27 Jan 2007 04:49:12 +0100, Bill Westphal wrote:

Okay, it's time for a rant. That is exactly at the heart of it.
[rantsnip]
[Usenet history and jargon goes here]
[snip]

It's also good to change the title when the topic changes. :-P

/me puts on nomex underpants.

On Jan 26, 3:30 pm, Michael Press wrote:
In article ,



"Mamba" wrote:
"Michael Press" wrote in message
...
In article
.com
,
"ddog" wrote:
Michael Press wrote:
snip

Do not top post. I fixed it for you.

In the cases reported I spent _less_ time with the
brakes on. I was not dragging the brakes as you say.

I am curious about the "top post" comment. It appears that bottom posting
encourages bandwidth waste and the inclusion of way too much verbiage,
especially in longer threads. Since all prior occurances in the thread
would likely contain the same stuff, seems redundant.

I realize that some folks use readers that make this desirable, and I'm not
flaming. Just curious about why this became the "way" to do it on usenet?USENET is a protocol on port 119. It was invented by
the elders who built the internet to propagate
technical news about the network.

I thought Al Gore started the internet....he's not that old.....

This requires an easy
to follow thread format so folks could easily identify
what was important for them in maintaining their
connection and holding up their end in maintaining the
network at large.

Naturally enough the channel expanded into tangential
discussions, as any group of like minded folk are wont
to do.

On technical newsgroups bottom posting is a necessity
for ease of understanding. We often need to go back in
a discussion to see exactly where a sub-thread took a
particular turn.

It is easy to top post. The top poster knows what he
has to say and its relevance to what was previously
written. Those who read the top post later,
particularly two or three articles later do not have
the benefit of knowing what the top poster was
thinking.

--
Michael Press

Check both the rim and pads for signs of unusual wear; specifically,
if the
rim is significantly worn, you can end up with a lip near the top and
bottom. As the brake pads wear, pressure is at first applied to the very
small surface area of the lip, after which it drops down into the main
section... which can suddenly increase the braking forces.

--Mike Jacoubowsky
Chain Reaction Bicycleswww.ChainReaction.com
Redwood City & Los Altos, CA USA

No Mike, I don't think this is the way it works. I have also
experience this phenomena with KoolStop pads (I haven't experienced it
with other pads purely because I have used Koostops for a while now
and have not had the chance to try and repeat the phenomena with other
pads) and the effect is repeatable. Ride the brake and suddenly brake
force increases. Cool it down a bit, ride it again and it does the
same all over again. On inspection, you don't see any noticeable
change in the pad appearance.

I believe it is temperature related and that something happens at a
critical temperature at the interface of rim and pad.

I also remember once that after applying using the brakes for a
specific period of time, they suddenly blew off debris which landed on
and stuck to on my thighs - little shavings of black rubber
grindings. This was before I used Koolstop pads. I remember
distinctly that this only happened a while into braking, not
immediately. I'm pretty certain that I applied continuous pressure to
the levers throughout, in both cases cited above.

Johan Bornman

Johan Bornman wrote:
Check both the rim and pads for signs of unusual wear; specifically,
if the
rim is significantly worn, you can end up with a lip near the top and
bottom. As the brake pads wear, pressure is at first applied to the very
small surface area of the lip, after which it drops down into the main
section... which can suddenly increase the braking forces.

Mike, I don't think this is the way it works. I have also
experience this phenomena with KoolStop pads (I haven't experienced it
with other pads purely because I have used Koostops for a while now
and have not had the chance to try and repeat the phenomena with other
pads) and the effect is repeatable. Ride the brake and suddenly brake
force increases.

I've never noticed this with Kool Stop Salmon pads. The only reason I
can think of for braking power to increase over time would be if there
was water (or even more so, snow) on the rims. Snow on the rims will
keep the rims wet until all the snow is gone. When the water is
finally squeegied away, the braking power with increase.

Cool it down a bit, ride it again and it does the
same all over again. On inspection, you don't see any noticeable
change in the pad appearance.


Could be dirt or grit getting trapped between the pad and rim. Pumping
the brakes a few times will usually clear that with Kool Stops.

Art Harris

On Jan 24, 6:21 pm, Michael Press wrote:
---snip---

At a later point in the brake
application, the braking force suddenly increased
sharply. This happened more than once.
---/snip---

I've noticed the same thing w/Kool Stop Salmons mounted on Dia Compe
Radius (BRS 200) single pivot calipers. Running the same pads/holders
on Tektro RX40 (dual pivot...more substantial) calipers did not reveal
the 'surge'. Because of this, I've come to wonder if the increase in
braking force is related to flex in the arms of the calipers -
specifically, as the brake force is applied, twisting force (from the
motion of the rim) causes the arms to flex 'out' at the fronts,
forcing the backs of the pads to 'dig in' to the rim - kind of a quasi
self energizing action. Just a theory, no data to back it up.

SYJ

In article
. com,
"Johan Bornman" wrote:

Check both the rim and pads for signs of unusual wear; specifically,
if the
rim is significantly worn, you can end up with a lip near the top and
bottom. As the brake pads wear, pressure is at first applied to the very
small surface area of the lip, after which it drops down into the main
section... which can suddenly increase the braking forces.

--Mike Jacoubowsky
Chain Reaction Bicycleswww.ChainReaction.com
Redwood City & Los Altos, CA USA

No Mike, I don't think this is the way it works. I have also
experience this phenomena with KoolStop pads (I haven't experienced it
with other pads purely because I have used Koostops for a while now
and have not had the chance to try and repeat the phenomena with other
pads) and the effect is repeatable. Ride the brake and suddenly brake
force increases. Cool it down a bit, ride it again and it does the
same all over again. On inspection, you don't see any noticeable
change in the pad appearance.

I believe it is temperature related and that something happens at a
critical temperature at the interface of rim and pad.

I also remember once that after applying using the brakes for a
specific period of time, they suddenly blew off debris which landed on
and stuck to on my thighs - little shavings of black rubber
grindings. This was before I used Koolstop pads. I remember
distinctly that this only happened a while into braking, not
immediately. I'm pretty certain that I applied continuous pressure to
the levers throughout, in both cases cited above.

I have not reproduced the phenomenon yet, as the
descents are not as steep since then. I did notice that
the KS pads were lipped over the outside edge of the
rim, so I adjusted that away. Now they squeal again!

The exact circumstance again is on a steep descent,
delay braking at corner approach, apply brake and
steadily increase brake pressure; then sudden increase
in braking with no increase in brake pressure.

--
Michael Press

In article
. com,
"SYJ" wrote:

On Jan 24, 6:21 pm, Michael Press wrote:
---snip---

At a later point in the brake
application, the braking force suddenly increased
sharply. This happened more than once.
---/snip---

I've noticed the same thing w/Kool Stop Salmons mounted on Dia Compe
Radius (BRS 200) single pivot calipers. Running the same pads/holders
on Tektro RX40 (dual pivot...more substantial) calipers did not reveal
the 'surge'. Because of this, I've come to wonder if the increase in
braking force is related to flex in the arms of the calipers -
specifically, as the brake force is applied, twisting force (from the
motion of the rim) causes the arms to flex 'out' at the fronts,
forcing the backs of the pads to 'dig in' to the rim - kind of a quasi
self energizing action. Just a theory, no data to back it up.

Thanks. The brakes are Ultegra dual pivot. No wet on
the road, but the air was damp and 50 F.

--
Michael Press