Don't do what I did
RimaNeas
rim... it was hell to find, but not unexpected, no big deal.
New front tire, only 1500 miles... descending a steep hill, blew
unexpectedly--yowzaa, hell to stay upright!! Looked like a snake bite, in
goes spare tube. Load pop, again, 100ft later. Hitched a ride home...
slightly bigger deal.
The new tire managed to tear its casing right at the same spot--very hard to
see in the failing light with failing eyes. Turns out my rim has a slight
(out of round) depression there, about 1mm. Worse, as my brake pads wore
down, the contact patch got wider... and one managed to scrape the tire
casing just so!!
It cost me a new tire and a couple of tubes, but happily, no skin.
Cheers, Shawn
Mark J.
Been there, done that, got the tee shirt. It /is/ really embarrassing,
but don't feel too bad. At least you didn't do what I did: got the
destroyed new tire replaced under warranty at a friend's shop before
realizing it was my own fault.
Glad you got away without injury.
Mark J.
(PeteCresswell)
>The new tire managed to tear its casing right at the same spot--very hard to
>see in the failing light with failing eyes. Turns out my rim has a slight
>(out of round) depression there, about 1mm. Worse, as my brake pads wore
>down, the contact patch got wider... and one managed to scrape the tire
>casing just so!!
Been there sort of... except in my case it was the basest
stupidity: I crashed, got up, rode away without inspecting the
bike and one of the front pads had cocked to where it was bearing
partially on the sidewall.
--
PeteCresswell
thirty-six
I know that sometimes it cant be helped, but is there any reason a
modern stud brake blockshould not be fixed on super tight?
Jobst Brandt
> Front tire had 6000 miles on it, casing developed a small tear,
> right at the rim... it was hell to find, but not unexpected, no big
> deal.
It IS a big deal! That can kill.
> New front tire, only 1500 miles... descending a steep hill, blew
> unexpectedly--yowzaa, hell to stay upright!! Looked like a snake
> bite, in goes spare tube. Load pop, again, 100ft later. Hitched a
> ride home... slightly bigger deal.
> The new tire managed to tear its casing right at the same spot--very
> hard to see in the failing light with failing eyes. Turns out my
> rim has a slight (out of round) depression there, about 1mm. Worse,
> as my brake pads wore down, the contact patch got wider... and one
> managed to scrape the tire casing just so!!
> It cost me a new tire and a couple of tubes, but happily, no skin.
You didn't say what brand and model of tire it was. That is highly
important if others are to be spared this failure. The reason I
mention it is that I also had such a failure and know what caused the
blowout that cost me a broken rib and a few weeks of no riding as such
injuries do.
This was a Continental "Grand Prix 4000" on which I descended many
steep and hazardous mountain roads. Only when It blew out did I
realize it was a design failure an that it could happen with straight
ahead miles. The tire is no longer sold by Continental. although they
don't say why.
It is my belief after inspecting these tires that they are flawed in
design because they have no chafing strip on the side of the clincher
bead as other reliable tires (clinchers and tubulars) have. With
miles of micro motions, the casing wears to the extent of failure.
All other tires have a chafing strip of a durable fabric at their
beads, intended to absorb the wear. The "Grand Prix 4000" does not,
apparently in an attempt to save a few grams weight.
What was your tire, and if you still have its remains, see if it has a
chafing strip?
Jobst Brandt
Bill Sornson
The one that almost killed me was a Michelin Pro Race 2. Bead separated
from the casing, causing (allowing better word) the tube to poke through and
blam. Of course it was a front tire, and of course it blew on a winding,
fast descent. I was extremely lucky to escape with a broken scapula, torn
rotator cuff, and surprisingly minimal road rash. Guess I "struck and
stuck" more than hit and slid. Brand new helmet trashed; best $25 I'll ever
spend. (Yes, it was a cheapo Bell.)
When I removed the REAR tire of same model (and batch I'd guess), sure
enough the casing around the bead was beginning to split open. Another
accident waiting to happen. (Although rear blow-outs aren't nearly as
dangerous.)
Michelin basically said "sorry for the inconvenience", but sure enough the
ProRace2 gave way to a new version pretty damned quickly. I, for one, won't
ever buy another Michelin product just for the principle.
Bill "still nervous on downhill turns" S.
Jobst Brandt
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.
Jobst Brandt
Dre
news:4b7b6892$0$1629$742e...@news.sonic.net...
Me, I love my hydro discs :)
Only thing I've *ever* had to do to any of mine (I have 5 sets/bikes, 3
Avid, 1 Hayes, 1 Magura) is change the pads when they wear out. Sweet!
Cheers Dre
RimaNeas
> ...
> This was a Continental "Grand Prix 4000" on which I descended many
> steep and hazardous mountain roads. Only when It blew out did I
> realize it was a design failure an that it could happen with straight
> ahead miles. The tire is no longer sold by Continental. although they
> don't say why.
>
> It is my belief after inspecting these tires that they are flawed in
> design because they have no chafing strip on the side of the clincher
> bead as other reliable tires (clinchers and tubulars) have. With
> miles of micro motions, the casing wears to the extent of failure.
> All other tires have a chafing strip of a durable fabric at their
> beads, intended to absorb the wear. The "Grand Prix 4000" does not,
> apparently in an attempt to save a few grams weight.
>
> What was your tire, and if you still have its remains, see if it has a
> chafing strip?
>
> Jobst Brandt
Yep, Conti GP 4000 it was--as is the one I replaced it with. But I do think
that they still sell that model, it is listed on their web site. The one
that I have likewise does not have a chaffing strip.... I recall the old GP
(before the 4000 bit) had a reddish chaffing strip that would often begin to
unravel with age and send cotton strings about.
(Since you are local, my tire blew going down Page Mill road... mercifully,
a little before the very steepest section. I don't think Lance, Sir Isaac,
and the three prophets together could keep me upright if it had blown in the
corkscrew section.)
Cheers, Shawn
Jobst Brandt
>> 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 :)
> Only thing I've *ever* had to do to any of mine (I have 5
> sets/bikes, 3 Avid, 1 Hayes, 1 Magura) is change the pads when they
> wear out. Sweet!
This isn't about disk brakes. Its caliper rim brakes that have pads
that approach the tire sidewall. I'm sure your disks don't have pads
that could come in contact with the tire casing.
Jobst Brandt
Jobst Brandt
>> ... This was a Continental "Grand Prix 4000" on which I descended
>> many steep and hazardous mountain roads. Only when It blew out did
>> I realize it was a design failure an that it could happen with
>> straight ahead miles. The tire is no longer sold by
>> Continental. although they don't say why.
>> It is my belief after inspecting these tires that they are flawed
>> in design because they have no chafing strip on the side of the
>> clincher bead as other reliable tires (clinchers and tubulars)
>> have. With miles of micro motions, the casing wears to the extent
>> of failure. All other tires have a chafing strip of a durable
>> fabric at their beads, intended to absorb the wear. The "Grand
>> Prix 4000" does not, apparently in an attempt to save a few grams
>> weight.
>> What was your tire, and if you still have its remains, see if it
>> has a chafing strip?
> Yep, Continental GP 4000 it was--as is the one I replaced it with. But I
> do think that they still sell that model, it is listed on their web
> site. The one that I have likewise does not have a chaffing
> strip.... I recall the old GP (before the 4000 bit) had a reddish
> chaffing strip that would often begin to unravel with age and send
> cotton strings about.
Continental is noted for frazzled casing threads from the days of
tubulars, 50 years ago. So get rid of that tire, now! The Gator skin
tires have chafing strips and the GP 4000 is fine in the new tire
test, but it wears out and blows out. I talked to the Continental man
at InterBike last fall. He said they discontinued that tire while
disclaiming any knowledge of why or what caused my failure.
> (Since you are local, my tire blew going down Page Mill
> road... mercifully, a little before the very steepest section. I
> don't think Lance, Sir Isaac, and the three prophets together could
> keep me upright if it had blown in the corkscrew section.)
You're lucky. I'm still "gun shy" descending because mine blew out
descending the first mile of Mount Hamilton Road east on a benign
curve so I went down slowly, but the pavement had a new chip seal and
ate my right side and cracked a rib... ouch!
I bought my sons new Ultra Gator Skins and demanded they replace them
now! In contrast, I descended the horrendous passes in the Alps with
the GP 4000 a year ago. Ouch. That's what scares me. It's a 1000m
drop if you blow a tire and go over the edge.
http://www.trentobike.org/byauthor/JobstBrandt.html
Do it, soon Shawn. Get rid of those faulty tires.
Jobst Brandt
AMuzi
Three? Von Mises, Hayek and Ayn Rand perhaps?
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Ronko
jbr...@sonic.net says...
Tosspot
Dogs way of telling you to get Magura Hydraulic rim brakes :-)
Jobst Brandt
>> Interesting.
I think you haven't been following the thread. The tire failure
occurs from wear between rim and tire bead and that is why tires
usually have a chafing strip on the bead. Just look at any of your
tires and you'll see it. The tire will fail just as well from riding
disk brakes, the tire motion on the rim being no different.
Tire failure from brake pad intrusion is an entirely different process
and results from cosine error in the brake arm.y
Jobst Brandt
Jim A
> "Jobst Brandt" <jbr...@sonic.net> wrote in message
> news:4b7b6892$0$1629$742e...@news.sonic.net...
>> 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.
>>
>> Jobst Brandt
>
> 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.
--
www.slowbicyclemovement.org - enjoy the ride
thirty-six
Tangential error included above
RimaNeas
> ...
> You're lucky. I'm still "gun shy" descending because mine blew out
> descending the first mile of Mount Hamilton Road east on a benign
> curve so I went down slowly, but the pavement had a new chip seal and
> ate my right side and cracked a rib... ouch!
>
> I bought my sons new Ultra Gator Skins and demanded they replace them
> now! In contrast, I descended the horrendous passes in the Alps with
> the GP 4000 a year ago. Ouch. That's what scares me. It's a 1000m
> drop if you blow a tire and go over the edge.
>
> http://www.trentobike.org/byauthor/JobstBrandt.html
>
> Do it, soon Shawn. Get rid of those faulty tires.
>
> Jobst Brandt
Oh oweeeee... rough roads and skin are a bad combination, hope you have
recovered by now. Many thanks for the info... sadly I still have 4 new
tires... but methinks skin (and ribs) are worth more. I will get new ones.
Cheers, Shawn
thirty-six
Larger tangent.
thirty-six
With all that knowledge, it makes you appear very foolish for using
such a tyre for work in mountainous country in the first place.
Especially someone who had already used tubulars extensively.
thirty-six
Jeez, I don't have this trouble with tubs, just that its difficult to
find good ones at a good price.
Tom Sherman °_°
--
Tom Sherman - 42.435731,-83.985007
"And for those of us who have never enjoyed job security, union
protection, tenure, a retirement plan, a secure job in a solid
corporation or booming industry, the jobs we do to put the
macaroni on the dinner table are ours to select only from the jobs
we are offered" - Christopher Cooper
Peter Cole
After the current meltdown, obviously the three false profits -- just
ask Greenspan....
RobertH
Continentals are the only brand of tire that seems to require an exo-
skeleton on its sidewalls to keep them from blowing out. Why don't you
buy your sons a better brand of tire?
Dre
I know, I just read all that info you posted and thought, bah, my discs are
so simple and just work and work and work and work.
I dont miss the old rim brakes for a second and your post just confirmed it!
Cheers Dre
Dre
news:4b7b9f83$0$2523$da0f...@news.zen.co.uk...
Yep, it would have to be a bloody good reason for me to go back to rim
brakes :)
Cheers Dre
andre...@aol.com
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.
Andre Jute
You and he are both talking about the three wise men, though of course
one of them is a woman.
Andre Jute
Ah, the benefits of a classical education are-- hmm, well, they'll
come to me
Tim McNamara
Jobst Brandt <jbr...@sonic.net> wrote:
There are a few cantilever designs from the 40s and 50s that used
various mechanisms (cams and the like) to create a straight or nearly
straight pad motion perpendicular to the rim. None of them survived in
the market so there must have been other drawbacks.
--
"I wear the cheese, it does not wear me."
Jobst Brandt
>>>> Interesting.
> I know, I just read all that info you posted and thought, bah, my
> discs are so simple and just work and work and work and work.
> I don't miss the old rim brakes for a second and your post just
> confirmed it!
The CP 4000 will fail just the same with hub and disk brakes because
it is continual wear between rim and tire bead. In the absence of a
chafing strip, the sidewall will wear thin and blow out. That is the
point I am making on the failure of these tires under so called ideal
conditions, the ones I had for a long time before failure. It was
then that I noticed that the tire casing wrapped directly around the
bead wire with no chafing strip.
Jobst Brandt
Jobst Brandt
>>>> 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
(PeteCresswell)
>...thinking of getting disk brakes but it would require that I
>buy new rims...
??
--
PeteCresswell
Michael Press
AMuzi <a...@yellowjersey.org> wrote:
Euler, Gauss, Lagrange.
--
Michael Press
Dre
Yes I understand the point you are trying to make. But in doing so you have
said a hell of a lot about rim brakes and this is what I'm replying to. I
run MTB's so have absolutely NFI about those types of tires you mention.
Me, I generally run 2.5" wide dual ply DH type tires and I dont worry about
tearing a sidewall, not even when I bash them past sharp rocks on my runs...
Cheers Dre
Dre
Thats nice and once more, I know what you are saying!!!! This thread talks
both about tires and brakes. Threads drift, is that a problem?!?!?
Cheers Dre
Frank Krygowski
>
>
> 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
andre...@aol.com
Jim A
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.
thirty-six
Tubasti works with regular tyres just fine.
thirty-six
But what of the trig lesson?
sergio
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
Peter Cole
> 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.
sergio
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
Frank Krygowski
> 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
Jobst Brandt
>>>>>> 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 disks.
>>>> 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.
Speed has nothing to do with tire fretting motion and possible damage
to GP 4000 tire casings. It is the wheel load that causes the tire to
deform under load (bulge) at the road contact area, something that
causes fretting motions at the bead.
Because bicycles must have bias ply tires (to remain constricted to
the rim when inflated), the tire bulges widest before and after the
ground contact patch with a negative bulge in the center of the
contact patch, a characteristic of bias ply tires. If you still have
a car or motorcycle with bias ply tires, you can see that condition.
It is also visible on extra fat (bias ply) bicycle tires.
It was only with radial car tires that the deformation of the contact
patch got a visible belly at there. Bicycles don't have radials and
that wouldn't solve the fretting problem either. That is why bicycle
tires require a chafing protector between casing cords and rim bead.
The GP 4000 does not have a chafing strip on its beads and is,
therefore, prone to fretting failure after significant mileage.
Jobst Brandt
Jobst Brandt
>>> 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.
It is fretting between tire and rim and, TUBASTI, a tubular tire glue,
does not prevent creep when braking as the rim heats from braking.
All tubulars develop aluminum debris on the base tape with use, but
this is relatively benign because base tape wear usually does not
reach the structural sidewall... and the base tape can be replaced.
> And one to 3-6.
> Are you serious that you (would?) glue regular tires, as if
> tubulars, onto the rim?
Not to worry. This is just another of Trevor Jeffrey's specious
suggestions. He doesn't do these ridiculous things anyway.
Jobst Brandt
Jobst Brandt
> 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 accommodating the screw of the pad holder to
> lower it a couple of millimeters. That works, too.
That sounds like a brake caliper designed for a short reach fork. I
recall when that became a new fad and most brake pads were too high.
The bicycle industry goes through these phases because they cannot
afford hiring good engineers who have experience in the subject. Most
of their people are old bicycle racers or mechanics, not engineers who
understand the workings (and failures) of components. 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.
How else could Continental make unreliable bicycle tires for so many
years? These are not car tires!
Jobst Brandt
Lou Holtman
> 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
Frank Krygowski
> 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
Jobst Brandt
>> I always admired the anonymous man who designed all 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.
I'm sure they are not. I met most of them when they were older and
Tullio, his engineer, Cinelli, Sacchini, Valsassina, Sieber (Chiasso)
and the boss at Clement tires (Milano). They all lived to ripe ages
before I read their obituaries while still in Europe. Cinelli made it
to 101 years at home in Chiancano, Toscana.
Just recall how a brake cable is anchored on the brake caliper...
non-slip, causes no kink or damage to cable strands, is easily engaged
manually and clamped by tightening with the 8mm (C) T-wrench (or a
5/16" [yellow handle] Spin-tight). 10mm socket, box/open-end will
took care of most other items, including the seat post clamp and
saddle screws.
I'll admit the saddle screws are difficult to manage but they replaced
a far worse system and are infinitely more adjustable and reliable.
Some things cannot be made simpler and this one tells the story. The
single screw seatposts of today are fatally dangerous, as I described
here not long ago. The screws fail and drop the rider onto the
rotating rear wheel for an automatic colostomy.
Jobst Brandt
Nate Nagel
> 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
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
Tim McNamara
Michael Press <rub...@pacbell.net> wrote:
Rumour spreadin' a-'round in that Texas town
'bout that shack outside La Grange
and you know what I'm talkin' about.
Tim McNamara
Nate Nagel <njn...@roosters.net> wrote:
> 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.
My Volvo came with Michelins and peculiarly I would get a lot of static
electricity shocks when getting into or out of the car. When they wore
out I bought new tires and that problem went away. I was told by the
tire guy that he had heard of this before and thought it was something
about the rubber compound Michelin uses. Those tires were also *awful*
in the snow.
> 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).
The best tires I have driven on are the Nokians on my wife's Volvo.
Peter Cole
> On Feb 18, 8:56 am, Peter Cole <peter_c...@verizon.net> 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 think it's a good deal less likely with mountain bike rims, they being
typically much wider (greater distance to the spokes).
Maximum brake force comes during panic stops on level, firm surfaces.
Steep downhill braking, particularly on the loose surfaces typical of
off road cycling, doesn't lend itself to high force unless you want to
either skid the front wheel (and almost certainly crash) or nose wheelie
into an endo. Consistent, predictable and uniform braking is the
important thing in cycling (quickly) over steep and rough trails.
> 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.
Never happened to me (or anyone I've ridden with), but I have seen a few
cases (including one of mine) with road wheels.
> 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?"
You seem to have a soft spot for conspiracies. I have yet to
catastrophically fail a MTB frame or component, while I've broken a
couple of road frames and a few other components. I've built most of my
bikes up from components. Where possible, I use MTB parts on road bikes.
They're generally cheaper and more reliable.
The rim wear issue typically comes from riding in wet conditions --
either on or off road. I rarely ride in wet conditions off road, it's a
practice frowned upon. I have yet to retire a MTB rim from wear.
Virtually all new MTB's use disk brakes, anyway.
N8N
> In article <hlkjbe02...@news6.newsguy.com>,
> Nate Nagel <njna...@roosters.net> wrote:
>
> > 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.
>
> My Volvo came with Michelins and peculiarly I would get a lot of static
> electricity shocks when getting into or out of the car. When they wore
> out I bought new tires and that problem went away. I was told by the
> tire guy that he had heard of this before and thought it was something
> about the rubber compound Michelin uses. Those tires were also *awful*
> in the snow.
I haven't noticed that, and well, really, *no* "all season" tires are
good in more than an inch or two of snow.
>
> > 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).
>
> The best tires I have driven on are the Nokians on my wife's Volvo.
Never tried those, but heard good things about them. I did buy a set
of Dunlop Winter Sports on closeout a couple years ago for the 944 and
they transform the car from undriveable to pretty darn capable in the
snow. (it doesn't help that the only real choice still available for
summer tires for that car are Yokohama AVS's which are *not* all-
seasons... so you pretty much have to have a set of snow tires, or
park it in the winter)
nate
Frank Krygowski
> Frank Krygowski wrote:
> >
>
> > 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?"
>
> You seem to have a soft spot for conspiracies.
"Umm, I think it's a joke, sir..." - from the film "Life of Brian"
Perhaps I should label them in the future?
- Frank Krygowski
Peter Cole
Yes, please, and don't quit your day job.
Tom Sherman °_°
> [...] since I have 2.4 tires [...]
What does the 0.4 tire do? ; )
--
Tom Sherman - 42.435731,-83.985007
Tad McClellan
> andre...@aol.com aka Andrés Muro wrote:
>> [...] since I have 2.4 tires [...]
>
> What does the 0.4 tire do? ; )
Anything it wants to, since the 2.0 tires are
doing the "holding it off the ground" thing.
--
Tad McClellan
email: perl -le "print scalar reverse qq/moc.liamg\100cm.j.dat/"
Tom Sherman °_°
> [...]
> Because bicycles must have bias ply tires (to remain constricted to
> the rim when inflated), the tire bulges widest before and after the
> ground contact patch with a negative bulge in the center of the
> contact patch, a characteristic of bias ply tires. If you still have
> a car or motorcycle with bias ply tires, you can see that condition.
> It is also visible on extra fat (bias ply) bicycle tires.
You can buy a new radial bicycle tire:
<http://www.maxxis.com/Bicycle/Road-Racing/Radiale-22c.aspx>. There were
also the older Panaracer radials in the mid 1980's and the handmade
radials of Jochen Rinkowski in the 1960's.
How did these tires stay on?
Jobst Brandt
>> [...] Because bicycles must have bias ply tires (to remain
>> constricted to the rim when inflated), the tire bulges widest
>> before and after the ground contact patch with a negative bulge in
>> the center of the contact patch, a characteristic of bias ply
>> tires. If you still have a car or motorcycle with bias ply tires,
>> you can see that condition. It is also visible on extra fat (bias
>> ply) bicycle tires. [...]
> You can buy a new radial bicycle tire:
http://www.maxxis.com/Bicycle/Road-Racing/Radiale-22c.aspx
> There were also the older Panaracer radials in the mid 1980's and
> the handmade radials of Jochen Rinkowski in the 1960's.
> How did these tires stay on?
With pure luck and strong wire beads. As I said, the bicycle industry
builds lots of ill advised products as the GP 4000.
Where are they today? Not understanding the effect of bias ply on
reliability is common. I wouldn't have to have included it in "the
Bicycle Wheel" were it obvious to the industry. How many of them are
aware of the cord angle in their garden hoses (35.27° instead of 45°)
or why tubular tires stay on rims, even with poor glue.
Jobst Brandt
Jobst Brandt
>>> [...]
>>> Because bicycles must have bias ply tires (to remain constricted
>>> to the rim when inflated), the tire bulges widest before and after
>>> the ground contact patch with a negative bulge in the center of
>>> the contact patch, a characteristic of bias ply tires. If you
>>> still have a car or motorcycle with bias ply tires, you can see
>>> that condition. It is also visible on extra fat (bias ply)
>>> bicycle tires.
>>> [...]
>> You can buy a new radial bicycle tire:
http://www.maxxis.com/Bicycle/Road-Racing/Radiale-22c.aspx
> I'll be interested when they have it in a more versatile width.
>> There were also the older Panaracer radials in the mid 1980's and
>> the handmade radials of Jochen Rinkowski in the 1960's.
>> How did these tires stay on?
> Any clincher stays on because the beads fit the seats of the rim.
> This is the case on truck, car, motorcycle, and bicycle tyres, and
> bicycles are the only ones where radials are rare.
Not so. Bicycle rims use a bead that is re-entrant so the tire bead
must be large enough in circumference to be slip over that bead to be
mounted on it. There are tires made by manufacturers who don't
understand the concept and that the bias ply makes sure tires don't
slip off the rim. Such tires are hard to mount without great effort
causing pinch flats in the inner tube.
Jobst Brandt
Jobst Brandt
http://www.maxxis.com/Bicycle/Road-Racing/Radiale-22c.aspx
> Wrong.
> Bicycle rims don't have beads, just like any other rims. Bicycle
> _tyres_ have beads, and they work (or are supposed to) just the same
> way as on any other vehicle using beaded tyres.
Maybe your rims have no bead but both bicycle tires and rims for good
clinchers have beads that overlap each other and, under pressure,
secure the tire. I'm not sure what your point is but the explanation
I gave above is unambiguous.
> If you can't tell the difference between a tyre and a rim, you are
> likely to get a lot of punctures lacing your wheels up.
You might follow that advice yourself. By now you should be aware
that I understand the mechanics of tires and rims, for both clincher
and tubular tires.
Jobst Brandt