Brake toe-in and squealing

D.M. Procida said:

What is the "front" of the shoe? The part which is facing the front of
the bicycle? Or the part which faces the oncoming wheel rim?

Front= front pointing toward the front of the bike.

Oily/dirts rims cause brakes to squeal too - might be worth just wiping
them down with a some detergent on a cloth.

D.M. Procida said:

What is the "front" of the shoe? The part which is facing the front of
the bicycle? Or the part which faces the oncoming wheel rim?

Front= front pointing toward the front of the bike.

Oily/dirty rims cause brakes to squeal too - might be worth just wiping
them down with a some detergent on a cloth.

D.M. Procida said the following on 28/07/2006 09:22:

Quoted message said:

My new brake pads squeal.

I am confused by descriptions and illustrations of toe-in. For example,
Sheldon says: :The shoe should be set so that the front edge of the shoe
contacts the rim slightly before the rear edge."

What is the "front" of the shoe? The part which is facing the front of
the bicycle? Or the part which faces the oncoming wheel rim?

I would have thought the latter, except that the illustration on the
back of the packet of brake blocks shows the opposite.

No, it refers to the front of the bike. If the back edge contacts
first, the blocks will squeal like buggery!

--
Paul Boyd
http://www.paul-boyd.co.uk/

It is sods law. My experience is that some blocks just don't like the
rims and will squeal whatever you do. Again it is a personal
observation that the 'harder' the brake block the worse the squeal, so
try changing the blocks to a 'softer' type presuming they are alloy
rims.

nobody760 said:

My experience is that some blocks just don't like the
rims and will squeal whatever you do.

Yeah, Aztec cartridge pads are dreadful squealers IME. I'm currently on
my 3rd set. Once I've used them all up, I'll go back to the Aztec
one-piece blocks that I've been using for years with no problems.

Quoted message said:

Again it is a personal
observation that the 'harder' the brake block the worse the squeal, so
try changing the blocks to a 'softer' type presuming they are alloy
rims.

Hmmm, I wonder if the cartridge pads might be harder than the one-piece
blocks. I'd expect them to use the same compound.

--
Danny Colyer <URL:http://www.colyer.plus.com/danny/>
"He who dares not offend cannot be honest." - Thomas Paine

D.M. Procida said:

My new brake pads squeal.

I made them toe-in more, and now they don't.

Daniele

D.M. Procida said:

Quoted message said:

My new brake pads squeal.

I made them toe-in more, and now they don't.

Except when wet. Now it sounds like I am slaughtering a pig at every red
light.

Daniele

"Blonde" <[email hidden]> wrote:
| D.M. Procida wrote:
| > What is the "front" of the shoe? The part which is facing the front of
| > the bicycle? Or the part which faces the oncoming wheel rim?
| Front= front pointing toward the front of the bike.

Can I suggest that the best way of remembering apparently arbitrary
"handed" things like this is to understand why they're that way about.
[I see no logic in calling it toe-in when it's really toe-out (or
vice versa depending on whether you stand on the frame, the rim, or
the pad).]

Forget the bike and the wheel for a minute and concentrate on a pad
and a patch of rim: the rim is passing you left-to-right and the pad
is coming down from above. If the left hand ("leading"?) end of the
pad makes contact first (and presses harder) you will compress that
end of the pad and it will trip over its toes juddering along as the
surface of the pad compresses to the right, pushing the pad up and
releasing pressure on the rim and uncomressing to the left and then
catching again. If the right-hand ("trailing"?) edge of the pad makes
contact first, it will stretch the surface of the pad pulling the pad
down even further and making much more even contact on the rim. It
is the first of these that makes a noise; the second is what you want
to achieve.

Then it is just the usual problem of transforming what you understand
in rim-and-pad coordinates into world coordinates where everything is
upside-down, back-to-front, and standing on its side.

Since the top of the rim is actually moving forwards at twice the speed
of the bike, the leading edge of the pad is the one near the back of
the bike; and you want the trailing edge, which is towards the front
of the bike, to be closing in on the rim first.

Er, obviously.

Geraint Jones <[email hidden]>

Quoted message said:

Forget the bike and the wheel for a minute and concentrate on a pad
and a patch of rim: the rim is passing you left-to-right and the pad
is coming down from above. If the left hand ("leading"?) end of the
pad makes contact first (and presses harder) you will compress that
end of the pad and it will trip over its toes juddering along as the
surface of the pad compresses to the right, pushing the pad up and
releasing pressure on the rim and uncomressing to the left and then
catching again. If the right-hand ("trailing"?) edge of the pad makes
contact first, it will stretch the surface of the pad pulling the pad
down even further and making much more even contact on the rim. It
is the first of these that makes a noise; the second is what you want
to achieve.

See, I thought (inasmuch as it deserves to be called "thinking"😉 it
would be the other way round; that having the pads toed-in to the
advancing rim would help clamp them down on to it progressively. A bit
like a car's drum brakes, kind of.

Daniele

Geraint Jones said:

"Blonde" <[email hidden]> wrote:
| D.M. Procida wrote:
| > What is the "front" of the shoe? The part which is facing the front of
| > the bicycle? Or the part which faces the oncoming wheel rim?
| Front= front pointing toward the front of the bike.

Can I suggest that the best way of remembering apparently arbitrary
"handed" things like this is to understand why they're that way about.
[I see no logic in calling it toe-in when it's really toe-out (or
vice versa depending on whether you stand on the frame, the rim, or
the pad).]

That reminds me of a trip to the "Electric Mountain" at Dinorwig. The
guide pointed upwards to a very large rotating thingy and asked whether
it was rotating clockwise or anticlockwise. I asked whether she meant as
viewed from the top or the bottom. Her reply was that it would make no
difference.

Quoted message said:

Er, obviously.

--

JimP

" " - John Cage

Jim Price <[email hidden]> wrote:
| That reminds me of a trip to the "Electric Mountain" at Dinorwig. The
| guide pointed upwards to a very large rotating thingy ...

Oooh. There wasn't anything rotating (except the tour landrover's wheels,
and some drills and things like that) when I was inside the mountain in
Dinorwig. Same thing for Beinn Cruachan. Should I go again and see what
they are like with working bits? (I can also remember going around
Trawsfynydd station before it was commissioned. They really did tell us
it was going to be too cheap to meter. They did. I'm getting old.)

Geraint Jones said:

Jim Price <[email hidden]> wrote:
| That reminds me of a trip to the "Electric Mountain" at Dinorwig. The
| guide pointed upwards to a very large rotating thingy ...

Oooh. There wasn't anything rotating (except the tour landrover's wheels,
and some drills and things like that) when I was inside the mountain in
Dinorwig. Same thing for Beinn Cruachan.

I didn't get to go there when it was being built as I was covering the
southern region at the time, so I got to go to the 2000MW cross channel
link site instead.

Quoted message said:

Should I go again and see what they are like with working bits?

Prolly, but take earplugs - so you don't have to listen to the rubbish
the guide talks. At least if you don't enjoy it the cycling around there
is great.

Quoted message said:

(I can also remember going around
Trawsfynydd station before it was commissioned. They really did tell us
it was going to be too cheap to meter. They did. I'm getting old.)

The meter was either broken or it had gone all the way round.

--

JimP

" " - John Cage