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Why do some forks and frames have brake rotor size limits?



 
 
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  #281  
Old November 1st 17, 09:57 PM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 4,699
Default Why do some forks and frames have brake rotor size limits?

On 2017-11-01 13:36, wrote:
On Wednesday, November 1, 2017 at 12:35:34 PM UTC-7, Joerg wrote:
On 2017-10-31 07:05,
wrote:
... As for your opinions on safety I can understand your position
after seeing how much weight you carry.


The difference isn't that large. 20-30lbs in extra bike equipment,
water and whatnot. It's peanuts.


You talk about 30 or 40 lbs as if it's chickenfeed. My C40 was about
17 lbs ready to ride and my Basso about 24. It took me several months
to get used to that weight difference. My Pinarello is 2 lbs lighter
and I can sure tell the difference.


I throw all sorts of stuf into my panniers, especially during errand
runs. The only time I feel the difference is when there is a top-heavy
box and bike wants to fishtail.

--
Regards, Joerg

http://www.analogconsultants.com/
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  #283  
Old November 2nd 17, 12:40 AM posted to rec.bicycles.tech
Doug Landau
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Posts: 1,338
Default Why do some forks and frames have brake rotor size limits?

On Tuesday, October 31, 2017 at 5:23:58 PM UTC-7, Frank Krygowski wrote:
On 10/31/2017 6:08 PM, AMuzi wrote:
On 10/31/2017 4:36 PM, wrote:
On Tuesday, October 31, 2017 at 8:27:04 AM UTC-7, Frank Krygowski wrote:
On 10/31/2017 10:29 AM, AMuzi wrote:
On 10/30/2017 10:37 PM, John B. wrote:
On Mon, 30 Oct 2017 22:52:12 -0400, Frank Krygowski
wrote:

On 10/30/2017 10:04 PM, John B. wrote:
On Mon, 30 Oct 2017 07:25:14 -0700 (PDT),
wrote:

You rarely have to worry someone is actually going to run you over.
After all if might get blood on their car that they'd have to wash
off. But the continuous threats are tiring. When I get back from a
long city ride - say my home down to Palo Alto along Hesperian then
back again - some 50 miles - I will be threatened at least two
dozen times with cars trying to nudge me off the road. Even with
open lanes they could easily pass in. Another thing is that you
will be riding along and a car will come up behind you fast, swerve
around you and turn directly into a driveway that causes you to
slam on the brakes. Usually a store or something.

I can only say that the U.S. must be different. I've ridden in
Japan,
Indonesia, Singapore, Malaysia and Thailand and have never, repeat
NEVER, had anyone threaten me, either by word or action. I also rode
in New Hampshire and Southern California, but that was a long
time ago
and I can't be sure but I certainly don't remember any acts that
were
threatening.

I can only say that other parts of the U.S. must be different,
because
what Tom describes almost never happens to me. Although my "other
parts
of the U.S." statement needs some modification, since I've ridden all
the way across it, and ridden at least a little in 47 states so far.

  #284  
Old November 2nd 17, 01:05 AM posted to rec.bicycles.tech
Joerg[_2_]
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Posts: 4,699
Default Why do some forks and frames have brake rotor size limits?

On 2017-11-01 13:32, wrote:
On Wednesday, November 1, 2017 at 12:30:19 PM UTC-7, Joerg wrote:
On 2017-10-31 07:27,
wrote:
On Monday, October 30, 2017 at 3:53:11 PM UTC-7, Joerg wrote:
On 2017-10-29 17:09, Frank Krygowski wrote:


[...]

It doesn't pay to be timid. Man up.


Why take the risk when there are alternatives such as this?

https://goo.gl/maps/XJk1gMRC2eA2

A bike lane plus segregated bike path plus bicycle bridge, all
seamlessly connecting to the Folsom bike path system and the
American River bike trail. Plus a lot of parks. That area is a
cyclists paradise. During rush hour it gets quite busy.

So what you're saying is that the percentage of bicyclists deaths
can be changed from nearly nothing to nothing?


It isn't nothing. About one a month in our local paper. However,
again, this is not only about deaths but also serious injury. I
personally knew people who have had that happen, usually by being
hit from behind. One woman wasn't able to ride for years because
she ended up underneath a Ford F-150. Later she never regained her
old performance level because some stuff didn't heal.


I'm certainly not saying that injuries aren't serious. Apparently the
pain I presently have in my right arm was caused by that crash I had
in July. It didn't bother me until maybe a month ago. Now I have to
go through physical therapy to try and quell the pain in my shoulder
from a torn ligament.

These sorts of things will always be around. The safest you can ever
hope to be is 100 times less safe than you would like to be.

https://www.youtube.com/watch?v=xdWsSB9QGkY

It is somewhat strange to me that no one seems to know why brakes
react the way they do. "disk brakes have more modulation". Well
that's because a rim brake has more leverage. There is a wider
distance between application of the disk brake and the full lock
position. I don't have any trouble with brake cables or quick
releases making noises.


I don't either and I am happy with the modulation of rims as well as
disc brakes. Just as the rider in the video say, disc brakes are worth
it in area that get a lot of rain. Such as here.


Looking at the available disk brake videos I have questions as to the
techniques they used to make these tests which showed good rim brakes
measurably less effective than disks.

https://www.youtube.com/watch?v=xdWsSB9QGkY

https://www.youtube.com/watch?v=uHFSSXOSnxs


IME there is only an advantage of disc brakes when it's wet out there.
Especially after riding through standing water and then having to stop hard.


I was incorrect about increased drag from disks: the difference was
too slight to mention.


Provided the set-up is done right they don't drag.


https://www.youtube.com/watch?v=HXQuSnKkS-I

My personal experiece with disk brakes is not particularly good. On
the heavy Trek HiFi they were very good. On my Redline Cyclocross
bike they are all hell and gone too powerful. I installed these when
the Shimano cantilever brakes on my Ridley couldn't stop a
caterpillar in full flight.

Later I installed TRP 9.0 V-brakes on the Ridley and even though the
Ridley is a lot heavier than the Redline, the braking was much more
predictable and powerful.


I've never issues with any brake in good weather. Just serious ones with
rim brakes in rain, sleet, snow, mud or after water puddles or creek
crossings. With disc brakes I can simply plow through and not worry
about a thing.

The fact that disc brakes don't eat rims is a definite bonus as well.

--
Regards, Joerg

http://www.analogconsultants.com/
  #285  
Old November 2nd 17, 02:54 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 3,652
Default Why do some forks and frames have brake rotor size limits?

On Wed, 01 Nov 2017 09:17:50 -0500, AMuzi wrote:

On 11/1/2017 1:46 AM, John B. wrote:
On Tue, 31 Oct 2017 20:26:15 -0700 (PDT), Frank Krygowski
wrote:

On Tuesday, October 31, 2017 at 10:17:36 PM UTC-4, John B. wrote:
On Tue, 31 Oct 2017 20:23:53 -0400, Frank Krygowski wrote:

I recently read up on "rolling coal" - that is, using modifications of a
pickup truck's diesel engine to purposely shoot dense black clouds of
unburned diesel fuel out the exhaust. I'd seen it done many times, but
had it done to me (and the folks I was riding with) only once.

The comments in the articles were disheartening. I didn't realize that
most of the people "rolling coal" are intent specifically on abusing
people who choose not to pollute. The comments bragged about taunting
Prius drivers, economy car drivers and bicyclists.

One source said there are no laws against this practice in other
countries, since they're not needed. Nobody else does it; it's just
American jerks.

Yes, we are not who we were.

Generally any diesel will smoke, to some extent, under some operating
conditions so I'd guess that no engine modifications would be
necessary.

This is an order of magnitude worse than "to some extent." For example, see
https://www.youtube.com/watch?v=rYPMbLO4pAY


It appears to be the usual diesel smoking on acceleration that all
diesel engines do to some extent. It does seem excessive as it is
right in your face but we have basically the same thing on some of our
older buses.


But more to the point, why in the world would anyone be worried about
whether someone else was emitting more or less contaminates?

You'd worry about the "more contaminants" if you were being forced to breathe
it.


Gee here is was trying to be politically correct and cover all options
and you complain.

Why would these jerks care if someone emits less? I think they think that
pollution is patriotic. If you can call that thinking.

- Frank Krygowski


Yes they are "jerks" but I suggest that if there is any thought taking
place it is probably "Hey! Look! Look! Everyone! Look at ME!"

--
Cheers,

John B.


Uh, it's an intentional modification:
https://www.youtube.com/watch?v=fF2zCXAQ3u0


Interesting. I had never owned a truck with a controllable turbo.

With an older turbo, or even an un-turbocharged engine, you simply
limited the engine rpm's and opened the throttle. My last sail boat
that was a bit "over propped" commonly did it maneuvering in close
quarters. Boat moving backward, prop in forward limits the engine RPM,
opening the throttle simply pours more fuel into the engine which
burns with a great deal of black smoke.

With my truck it just as easy. Foot on the brake thus limiting engine
RPM, other foot on the throttle, press and you increase fuel flow to
the engine causing a rich mixture and thus smoke.

--
Cheers,

John B.

  #286  
Old November 2nd 17, 03:09 AM posted to rec.bicycles.tech
Joy Beeson
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Posts: 1,009
Default Why do some forks and frames have brake rotor size limits?

On Thu, 02 Nov 2017 08:54:44 +0700, John B.
wrote:

With my truck it just as easy. Foot on the brake thus limiting engine
RPM, other foot on the throttle, press and you increase fuel flow to
the engine causing a rich mixture and thus smoke.


But that involves learning a little something, and thinking about how
you drive!

--
Joy Beeson
joy beeson at comcast dot net

  #287  
Old November 2nd 17, 03:09 AM posted to rec.bicycles.tech
John B.[_3_]
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Posts: 3,652
Default Why do some forks and frames have brake rotor size limits?

On Wed, 01 Nov 2017 12:27:36 -0700, Joerg
wrote:

On 2017-10-31 07:43, wrote:
On Monday, October 30, 2017 at 8:14:01 PM UTC-7, Frank Krygowski
wrote:
On 10/30/2017 6:53 PM, Joerg wrote:
On 2017-10-29 17:09, Frank Krygowski wrote:


... let me repeat: I've had some motorists act displeased when
I've ridden at lane center. I've never had one run me over.
I've never known another cyclist who had that happen.

I knew two personally who have been hit from behind. They
survived but one lost a kidney and the other had a ruptured
spleen. Then there was the woman here who got rear-ended in the
right lane at high speed. Died. Numerous others down in the
valley, including an off-duty police officer who was catapulted
off his road bike and died.

And I can double check my list, but I think it's now up to nine
friends who were killed in motor vehicle accidents. Zero on
bicycles. We can trade anecdotes (and you frequently do) but I give
more credence to unbiased data.

It doesn't pay to be timid. Man up.


Why take the risk when there are alternatives such as this?

https://goo.gl/maps/XJk1gMRC2eA2

Here's why I "take the risk," Joerg. First, the risk of being hit
while riding lane center is extremely low. Most of those hit that
way seem to be unlit cyclists riding at night, probably drunk or
nearly so. Data's a bit soft, but that does seem to be what it
shows.

But more important: If I waited for "alternatives" such as the one
you show to be built, I would have missed about 45 years of
enthusiastic adult riding. I'd have missed riding in about a dozen
different countries, 47 states and hundreds of different towns and
cities. I wouldn't have been able to ride my bike to work at four
different jobs. I'd have missed wonderful vacations with my family,
and I'd have missed making at least a hundred good cycling
friends.

I know many people have bought the "Danger! Danger!" mantra and
never leave the nice, safe (and horridly boring) bike path. I chose
instead to learn to be competent on ordinary roads. And I'm damned
glad I did.


We pretty much agree with this. I don't have to worry any more about
riding a bike around dangerous drivers than I would driving a car.
But that is a clear and present danger because the police no longer
enforce driving laws. Yesterday I was driving up the street and some
woman pulls a large SUV out of her driveway directly in front of me
forcing me to slam the brakes on. It is common for women especially
to pull out of parking lots or other driveways looking to the right
when traffic comes from the left.


With me that happened yesterday. School bus from the other side, driver
backed out of driveway with gusto into the school bus' path, the bus
driver swerved around and into my lane. If I had been lane center I'd be
in the hospital or morgue today. Luckily I rode AFRAP, the hydraulic
brakes of my MTB came on prontissimo and I was able to leave the road
without crashing because, well, it was an MTB.

Yes, the offending driver was a woman but I've seen guys do that as
well. She was visibly shaken by all that.


Gee Joerg, you must be riding on very crooked roads. The city streets
I ride on are straight enough that I can see, oh probably 50 feet in
front of me, and by watching I can see vehicles, way down the road,
that might be meaning to drive out into traffic and even braking by
dragging your feet lets you slow down enough to avoid them.

I think the modern term is "Defensive Driving" and it is usually
defined as "Its aim is to reduce the risk of collision by anticipating
dangerous situations, despite adverse conditions or the mistakes of
others."

Of course, the (also modern) street definition is "get your head out
of your arse". A bit impolite perhaps... but memorable.
--
Cheers,

John B.

  #289  
Old November 2nd 17, 04:34 AM posted to rec.bicycles.tech
Frank Krygowski[_2_]
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Posts: 6,961
Default Why do some forks and frames have brake rotor size limits?

On Wednesday, November 1, 2017 at 4:02:54 PM UTC-4, Joerg wrote:
On 2017-11-01 13:00, Frank Krygowski wrote:
On 11/1/2017 3:27 PM, Joerg wrote:

With me that happened yesterday. School bus from the other side,
driver backed out of driveway with gusto into the school bus' path,
the bus driver swerved around and into my lane. If I had been lane
center I'd be in the hospital or morgue today.


I don't think I'd have ended up in the hospital just because I rode at
lane center. I know about steering a bike.


Except when it's too late to get to the side or as in this case off the
road. But I know, you are superman and can easily put on a kilowatt or
two to do this uphill.


I didn't see anything about uphill speed helping to avoid this crash.

I have taught, practiced and been tested on bike emergency maneuvers several
times. It's something that happens if you take a Cycling Savvy class, for
instance. As I've previously described, I've used that once, long ago, to
avoid a somewhat similar crash. That one was a sudden left cross.

- Frank Krygowski
  #290  
Old November 2nd 17, 04:51 AM posted to rec.bicycles.tech
[email protected]
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Posts: 3,346
Default Why do some forks and frames have brake rotor size limits?

On Wednesday, November 1, 2017 at 2:18:04 PM UTC-7, jbeattie wrote:
On Wednesday, November 1, 2017 at 1:57:15 PM UTC-7, AMuzi wrote:
On 11/1/2017 3:39 PM, wrote:
On Wednesday, November 1, 2017 at 12:35:34 PM UTC-7, Joerg wrote:

A lever is never supposed to bottom out before the brake force on
respective wheel is maxed. If it did then he'd have faulty brakes and I
am sure he'd not have posted this. The guys look like serious cyclists
who know this.

How old are you again Joerg? With even the old Campy brakes it was possible to bottom out the levers often without locking the wheels.


Delta maybe but not the classic forged-arm sidepull.


Well adjusted, they had good stopping power -- particularly the short reach. I used standard reach NR side-pulls on my touring bike all the way across the US and on many tours. Great stopping even fully loaded -- using some of the Scott-Mathauser brake pads. The cooling fins made me go faster.


Four years ago when I was recovering and putting bikes together I had a super record set on a steel bike of some sort and they would bottom out bending the arms. Now they were long arm brakes but they did bottom out.
 




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