Cross-hatching, 'etching', sanding braking surfaces (pads and rims)

wrote:

There is another problem you might have. If you climb long grades
standing, you may drip sweat onto the front wheel from your face.
Salt water makes the squeakiest brakes. You can achieve the same
effect if you urinate while standing astride the bicycle such that a
bit of splash gets on the rim. Don't do that!

And some people think you can't get great advice on r.b.t... I know I
for one am going to avoid urinating on my front wheel now that I know
it can make my brakes squeak! ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

"Mark Hickey" wrote in message
...
wrote:

There is another problem you might have. If you climb long grades
standing, you may drip sweat onto the front wheel from your face.
Salt water makes the squeakiest brakes. You can achieve the same
effect if you urinate while standing astride the bicycle such that a
bit of splash gets on the rim. Don't do that!

And some people think you can't get great advice on r.b.t... I know I
for one am going to avoid urinating on my front wheel now that I know
it can make my brakes squeak! ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

Years ago over in NM, some of the racers mastered the art of relieving
themselves "on the wheel" so to speak.

We used to come over to Phoenix and Tucson for races. Most of the time in
the Southwest, it was so dry we never had to worry about stopping for
nature's call, we just sweated it out. ;-)

Chas.

"* * Chas" wrote in message
news
"John Ampleforth" wrote in message
...
snip
I used to be in the aluminium camp, but isn't there a large (20%) boron
content??? I suppose "Aluminium alloy" would be best.

Boron? 20%, Huh? Some of the common elements alloyed with aluminum are
copper, manganese, silicon, magnesium, zinc, chrome, and titanium. These
are rarely more than a few percent.

Here's a chemical breakdown of common aluminum alloys:

http://www.luskmetals.com/chemalum.html


in retrospect, i think the boron is experimental .... quick google
search.... this is what i had read:

http://whyfiles.org/sports/cycling/index.html

sounds promising.



**And this sentence should get the Infinitive Unification Front really
mad, too.

No-one speaks gooder english than like what i does, aghuh!

Here's something a friend sent me from Blighty:

"In response to your series of dialectical discussions, may I present a
few samples from around the UK. These all say approximately the same
thing and may lend some insight into British regional characteristics
as well.

GEORDIE: "Why, aye. Shall wa gan doon toon fer a cuppla bevies, then?"

BRUMMIE: "Duh yow wont ter coom owt fer a pint er two?"

YORKSHI "Ist'a coming downt' poob, lad? Tha's payin'."

WEST COUNTRY YOKEL: "Be thee be comin' down ter zup a few?"

COCKNEY: "'Ahs abaht cummin' dahn the ol' rub-a-dub an' sinkin' a couple?"

SLOAN: "Pimms, anyone?"

GLASGOW: "Ah'm gonnae go an' git rat-arsed. Are yez comin'?"
(later on, it's more likely to be: "Are yez lookin' a' me? Ah'll come
doon there an' gi' yez a smack roond the heed!")

WALES: "Ah, boyo, do you fancy a pint? Oh, bugger, it's Sunday - they're
shut."

Chas.

HA! mostly true too but unless you're mate lives in the 1980's i'm not sure
where he's encountering the sloans. 'One is quite confused!' (sic).
It's my understanding that the society for the protection of the English
language is actually stateside. "no taxation without representation! We will
appropriate your language and religions tho, cheers very much."

wrote in message
...
John Ampleforth writes:

I suspect you're right, I'll give Kool-Stop salmon a try before
dishing out for leather lined. If there's little improvement I'll
try the serrations and post back.

There is another problem you might have. If you climb long grades
standing, you may drip sweat onto the front wheel from your face.
Salt water makes the squeakiest brakes. You can achieve the same
effect if you urinate while standing astride the bicycle such that a
bit of splash gets on the rim. Don't do that!

Haha! You seem pretty certain about this, do you have any empirical data?


Of course you can remedy that situation by descending a STEEP grade
while braking, where it doesn't take long to clean the rim, or ride
through a mud puddle with the brake applied.

Jobst Brandt

wrote in message
...
John Ampleforth writes:

A squeegee leaves a super-thin water film which dries quickly just
behind the pass.

I'm surprised that no ones developed a 2 pass system where the rim
is dried first before the brake is applied??; doesn't seem beyond
the realms of possibility.

Give it some thought. Where is the wiper going to be? At the
interesting speeds of wheel rotation the brake pads would need to be
about a quarter rotation apart.

It's not that inconceivable. You engineers lose all sense of creative
genius, dump the rule book, join me on the edge.
I suspect some hydraulic piston with a leather or rubber wiper built in to
the side of the caliper controled by a secondary lever which exits behind
the brake lever, using the initial braking action to activate the piston.
obvious weight issues, there's always a trade-off tho.


Besides that, once heavy braking
occurs, the rim stays fairly dry.


I did a test on that with snow on the inner circumference of the
front wheel and noted that braking only became effective after all
snow had melted and run off. Then braking was nearly as good as when
dry, no significant water reaching the braking surface even in
moderate rain. In a downpour, rain splashing from the road curs
braking significantly, but then there is less traction on the road as
well.

How do you measure "...nearly as good as.."?
Less traction, so what? A compound which has more effective grip but retards
the bike at a slower rate would ensure effective/safe braking. Anyway, is
the degree of traction loss with the road that much of a factor? I thought
hydroplaning (for example) at even the fastest bicycle speeds and with any
currently availible tyre was virtually impossible or at least massive
negligible (sheldon brown).


Braking is conversion of motion to heat. Ceramics insulate rather
than conduct heat.

I see your point but isn't the heat rather incidental, the result of
friction? Whether or not the material is a conductor or insulator
shouldn't make a difference if friction exists should it?

The heat is all of it. You must turn kinetic energy to heat. That is
what a brake does.

Errrr, well, yes alright, i 'll give you that one but i'll not rest until i
develop an effective air brake and another one that converts Ke to
negative-heat.


Incidentally, will you post the leather lined to the UK?

Let me fill you in on that as well. If you read my ride report from
1959


http://www.trentobike.org/Countries/...f_the_Alps/195
9/

You'll note that unless the brake medium is thermally durable and the
rim a good heat conductor, there isn't much braking. I discovered
that the hard way after an old timer suggested I ride wood rims to
avoid overheating my tires. Well it did that, but the burning
particles from the brake pads weren't so good on my legs nor was
braking.

I'd be surprised if leather could stand up to braking on steel rims
that have a higher surface temperature than aluminum rims.

I guess what you say is logical. i have no personal experience of these
leather pads but others have assured me that they perform better with steel
than standard caliper pads, i'll give em a bash anyway


--

Jobst Brandt

On 2007-02-05, John Ampleforth wrote:

wrote in message
...
John Ampleforth writes:

A squeegee leaves a super-thin water film which dries quickly just
behind the pass.

I'm surprised that no ones developed a 2 pass system where the rim
is dried first before the brake is applied??; doesn't seem beyond
the realms of possibility.

Give it some thought. Where is the wiper going to be? At the
interesting speeds of wheel rotation the brake pads would need to be
about a quarter rotation apart.

It's not that inconceivable. You engineers lose all sense of creative
genius, dump the rule book, join me on the edge.
I suspect some hydraulic piston with a leather or rubber wiper built in to
the side of the caliper controled by a secondary lever which exits behind
the brake lever, using the initial braking action to activate the piston.
obvious weight issues, there's always a trade-off tho.

You shouldn't post ideas like that without patenting them first.

[snip]
I did a test on that with snow on the inner circumference of the
front wheel and noted that braking only became effective after all
snow had melted and run off. Then braking was nearly as good as when
dry, no significant water reaching the braking surface even in
moderate rain. In a downpour, rain splashing from the road curs
braking significantly, but then there is less traction on the road as
well.

How do you measure "...nearly as good as.."?
Less traction, so what? A compound which has more effective grip but retards
the bike at a slower rate would ensure effective/safe braking. Anyway, is
the degree of traction loss with the road that much of a factor? I thought
hydroplaning (for example) at even the fastest bicycle speeds and with any
currently availible tyre was virtually impossible or at least massive
negligible (sheldon brown).

Aquaplaning is not the same as the much more common phenomenon of a
wheel locking on a wet road.

I think aquaplaning is spontaneous gliding over a film of water on the
road at speed with resultant loss of control. You might get it in a car
with bald tyres and on a very wet road.

[snip]
I'd be surprised if leather could stand up to braking on steel rims
that have a higher surface temperature than aluminum rims.

I guess what you say is logical. i have no personal experience of
these leather pads but others have assured me that they perform better
with steel than standard caliper pads, i'll give em a bash anyway

You can get a perfectly good aluminium rim for GBP 10, might not cost
much if anything more than the leather pads, and you have the fun of
rebuilding the wheel. You might need spokes too I suppose if yours are
the wrong length.

John Ampleforth wrote:

Rims: is it safe to cross hatch/sand alloy rims? will it increase breaking
power or will it rip the pad up more leading to increased residue and less
grip?

Trials riders grind their rim sidewalls in the pursuit of the
grabbiest possible brakes. From what I understand, the grinding is
more to prepare the surface for having pitch rubbed on it than it is
for providing better braking by itself.

Allow me to observe that the kind of binary braking preferred for
observed trials might be less than ideal for general riding.

Chalo

"John Ampleforth" wrote in message
...

"* * Chas" wrote in message
news
"John Ampleforth" wrote in message
...
snip
I used to be in the aluminium camp, but isn't there a large (20%)
boron
content??? I suppose "Aluminium alloy" would be best.

Boron? 20%, Huh? Some of the common elements alloyed with aluminum
are
copper, manganese, silicon, magnesium, zinc, chrome, and titanium.
These
are rarely more than a few percent.

Here's a chemical breakdown of common aluminum alloys:

http://www.luskmetals.com/chemalum.html


in retrospect, i think the boron is experimental .... quick google
search.... this is what i had read:

http://whyfiles.org/sports/cycling/index.html

sounds promising.


They're talking about a metal matrix composite rather than an aluminum
alloy. These types of aluminum MMCs contain non metallic particles or
filaments like boron carbide, silicon carbide, aluminum oxide or a blend
of these materials. All three of these are hard ceramic like compounds
that are most commonly used as abrasives.

Aluminum MMCs are light and strong and have mainly been used in aerospace
applications. The problem with these materials is that they are difficult
for machine, form and fabricate.

http://en.wikipedia.org/wiki/Metal_matrix_composites

Chas.