Don't do what I did

Jobst Brandt wrote:
Andreas Bailly wrote:

Interesting.

I see some responses that lay blame on brake pads getting into
the tire. It is not idle that I warn against brakes that are not
single pivot side pull calipers, either center-pull, cantilever
or dual pivot, because the sweep of their brake arms rise into
the tire or fall below the rim into the spokes.

We have had discussions of these flaws for years with riders
defending their latest brake, nearly all having large "cosine
error". That is the technical term for a lever that does not
pivot in a small angle about the center of the fork crown as all
side pull brakes do.

In an effort to increase mechanical advantage, various mechanisms
have taken over from the side pull to promise less hand lever
force... the main purpose of the dual pivot caliper. That
leverage is achieved with large cosine error that presents a
safety hazard. If y0u back up a bit you can find the discussions
of the dual pivot brake and its flaws. The same occurs with
cantilever and centerpull brakes.

Me, I love my hydro discs

Ditto my drum brakes. All I've had to do to them in 2000 miles or
so is tighten the cable a little as it stretches.

I was glad to hear the cautionary tale though - I've just bought a
Dahon folder which has Vee brakes so I'll need to remember to check
them carefully and regularly.

Yep, it would have to be a bloody good reason for me to go back to
rim brakes

Once more! The general failure of these tires is not dependent on the
type of brake, although a poorly adjusted rim brake can cause failure.
These tires fail from fretting motion between rim and tire casing at
the bead, a motion that is independent of brake type.

I don't dispute that. Personally I prefer reliability so I don't ride a
dainty road-bike, I have drum brakes and I use Marathon Plus tyres.

Maybe I don't go so fast as you (speed isn't everything), but if there
are such fatal risks as you describe in running lightweight tyres I
think I've made the right decision.

--
www.slowbicyclemovement.org - enjoy the ride

On 18 Feb, 02:23, Jobst Brandt wrote:
Andreas Bailly wrote:
Interesting.
I see some responses that lay blame on brake pads getting into
the tire. *It is not idle that I warn against brakes that are not
single pivot side pull calipers, either center-pull, cantilever
or dual pivot, because the sweep of their brake arms rise into
the tire or fall below the rim into the spokes.
We have had discussions of these flaws for years with riders
defending their latest brake, nearly all having large "cosine
error". *That is the technical term for a lever that does not
pivot in a small angle about the center of the fork crown as all
side pull brakes do.
In an effort to increase mechanical advantage, various mechanisms
have taken over from the side pull to promise less hand lever
force... the main purpose of the dual pivot caliper. *That
leverage is achieved with large cosine error that presents a
safety hazard. *If y0u back up a bit you can find the discussions
of the dual pivot brake and its flaws. *The same occurs with
cantilever and centerpull brakes.
Me, I love my hydro discs
Ditto my drum brakes. *All I've had to do to them in 2000 miles or
so is tighten the cable a little as it stretches.
I was glad to hear the cautionary tale though - I've just bought a
Dahon folder which has Vee brakes so I'll need to remember to check
them carefully and regularly.
Yep, it would have to be a bloody good reason for me to go back to
rim brakes

Once more! *The general failure of these tires is not dependent on the
type of brake, although a poorly adjusted rim brake can cause failure.
These tires fail from fretting motion between rim and tire casing at
the bead, a motion that is independent of brake type.

Jobst Brandt

Tubasti works with regular tyres just fine.

On 18 Feb, 04:18, Frank Krygowski wrote:
On Feb 17, 7:10*pm, " wrote:
*



Interesting indeed. MY MTB has v brakes that work fine, but are
difficult to adjust. They were riding too low on the rim and a little
lip was forming on the bottom. I move them up a little, but since I
have 2.4 tires they would hit the tire sidewall as the moved towards
the rim. I had to adjust them carefully so that they get full contact
with the rim and not rub the tire as I squeeze the levers.

I've been thinking of getting disk brakes but it would require that I
buy new rims as well as calipers. The V brakes work pretty well though
and I am happy with them once properly adjusted.

I prefer the simplicity, reliability and field-repairability of
caliper brakes. *Also, calipers can be set to completely clear their
braking surface. *(I've ridden disks whose pads always had a light
scrape on the disk.) *I'd consider disks only for abrasive mud (as in
intense mountain biking) or rim overheating (as in extended, loaded-
bike mountain descents).

But about your brakes: *If I were having that much trouble
compromising between a lip on the bottom and tire contact on the top,
why not just take a utility knife to the brake blocks? *Trim them to
make them a bit narrower. *You'll get the same braking force with only
a little less wear life. *A good trade, I think, for avoiding a dive
into a spoke or chewing up your tire!

- Frank Krygowski

But what of the trig lesson?

On 18 Feb, 12:37, thirty-six wrote:
On 18 Feb, 02:23, Jobst Brandt wrote:
Once more! The general failure of these tires is not dependent on the
type of brake, although a poorly adjusted rim brake can cause failure.
These tires fail from fretting motion between rim and tire casing at
the bead, a motion that is independent of brake type.
Tubasti works with regular tyres just fine.

A question to Jobst.
I have seen failures that I traced to a weak sidewall of the casing
under repeated stretching, due to traction, in a direction parallel to
the rim.
Is that what you are talking about or do you really mean fretting
against the metal of the rim.

And one to 3-6.
Are you serious that you (would?) glue regular tires, as if tubulars,
onto the rim?

Sergio
Pisa

Frank Krygowski wrote:

But about your brakes: If I were having that much trouble
compromising between a lip on the bottom and tire contact on the top,
why not just take a utility knife to the brake blocks? Trim them to
make them a bit narrower. You'll get the same braking force with only
a little less wear life. A good trade, I think, for avoiding a dive
into a spoke or chewing up your tire!

I routinely shave off lips that form on brake pads. As the pads wear,
the contact surface moves down the rim face slightly. The only problem I
find with the lips is that the pads sometimes drag, not releasing fully
because of the lip. I can't imagine wear or misalignment being so bad
that the pad touches spokes.

I've failed a few tires at the bead from chafing, including several
Continentals. I stopped using them years ago, they were stupid
expensive, anyway. I've never torn a sidewall from a brake pad, although
I have had rubbing briefly when a pad got knocked, I'm careful to spin
wheels after that possibility now. I take front wheel blowoffs very
seriously.

On 18 Feb, 14:56, Peter Cole wrote:
I've never torn a sidewall from a brake pad,

I once got two flats in quick succession just because of that.
I later filed the slot accomodating the screw of the pad holder to
lower it a couple of millimeters.
That works, too.

Sergio
Pisa

On Feb 18, 8:56*am, Peter Cole wrote:
Frank Krygowski wrote:
But about your brakes: *If I were having that much trouble
compromising between a lip on the bottom and tire contact on the top,
why not just take a utility knife to the brake blocks? *Trim them to
make them a bit narrower. *You'll get the same braking force with only
a little less wear life. *A good trade, I think, for avoiding a dive
into a spoke or chewing up your tire!

I routinely shave off lips that form on brake pads. As the pads wear,
the contact surface moves down the rim face slightly. The only problem I
find with the lips is that the pads sometimes drag, not releasing fully
because of the lip. I can't imagine wear or misalignment being so bad
that the pad touches spokes.

I've heard of this happening with mountain bikers. I imagine it must
take a steep, slow-speed descent (so very large brake force) and very
bad pad alignment - which could be due to extreme pad wear in abrasive
mud, I suppose, and/or insufficient inspection of equipment.

I was on one mountain bike ride where another rider blew the sidewall
off a rim. Abrasive wear had weakened the rim to that degree.

I've long suspected that mountain biking is just a conspiracy by
component manufacturers and frame manufacturers. Road bikes and
equipment seem to last forever. Maybe manufacturers got together and
said "Hey, how can we get macho guys to break bike things so we can
sell replacements?"

- Frank Krygowski

Op 18-2-2010 17:58, Frank Krygowski schreef:

I've long suspected that mountain biking is just a conspiracy by
component manufacturers and frame manufacturers.

Mountain biking is deliberately ruining your equipment.
I had a hard time to accept that but you can minimize the
wear/maintenance of the components by choosing the right components.
Often not cheap but it gives me some piece of mind ;-).

Lou

On Feb 18, 12:27*pm, Jobst Brandt wrote:
*I always
admired anonymously the man who designed all of Campagnolo's early
components and tools. *The guy was a genius, but that's all gone now
along with Tullio.

I wonder if that man is still alive? I can imagine him giving an
excellent interview.

- Frank Krygowski

On 02/18/2010 12:27 PM, Jobst Brandt wrote:

How else could Continental make unreliable bicycle tires for so many
years? These are not car tires!

Jobst Brandt

To be fair, the only set of Continental car tires I've ever owned (not
by choice, they were factory) were abysmal. I often inadvertantly
"chirped" the tires backing out of parking spaces, the traction was that
poor. Replacing them with a set of Michelins was the single most
profound improvement I ever did to that car; I should have done it sooner.

The absolute worst tires I've had, but not *that* much worse than the
Continentals, were a set of Goodyear "Integrity" all-seasons. Sadly,
I've had them twice (factory fitted to both of my last two company cars)

nate

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