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

On 2017-10-27 09:43, Frank Krygowski wrote:
On 10/27/2017 4:34 AM, John B. wrote:
On Wed, 25 Oct 2017 08:59:46 -0700 (PDT), wrote:

I see no reason whatsoever for disk brakes and their complications
even on most MTB's since a good V-Brake is longer lasting, just as
effective, cheaper and doesn't require special wheels and frame and
fork changes.

Well, "cause I want 'em" is, I guess, a valid reason.

But not necessarily proof of superiority :-)

"I want 'em" is the ultimate decision point for lots and lots of
consumer goods.

Of course, people learn to "want them" after consuming tons of
advertising bull****.

I guess it keeps our economy going.


What really keeps the economy going is the "need it" because repeated
ads have told the consumer that life would just be miserable without.
That is how people who rarely use such a product enough get suckered
into expensive cell phone plans, cable TV subscriptions, a new car every
2-3 years, and so on.

That goes for cyclists as well. I know a guy who bought a $7500 carbon
deal and after more than half a decade has 10 miles on it. A $300
Walmart road bike would have been perfectly fine for him.

--
Regards, Joerg

http://www.analogconsultants.com/

On Fri, 27 Oct 2017 08:10:03 -0700 (PDT), wrote:

They are saying that FOAM broke a hole in the wing? What sort of foam was it - titanium?

The foam was moving at about 530 mph. Any impact at that speed is
going to hurt.

Here's some videos of tests and simulations to see what happened.
https://www.youtube.com/watch?v=2eTRaJGDe-8
https://www.youtube.com/watch?v=IgQ3ekcvyRA

Mo
"Foam Impact Velocity Demonstration - NASA History Office"
https://history.nasa.gov/columbia/Troxell/Columbia%20Web%20Site/CAIB/CAIB%20Website/news/FOAMIM~1.PDF
"Visual evidence and other sensor data established that the debris
came from the bipod ramp area and impacted the wing on the wing
leading edge. At this time Columbia was traveling at a speed of
about 2300 feet/second (fps) through an altitude of about 65,900
feet. Based on a combination of image analysis and advanced
computational methods, the Board determined that a foam projectile
with a total weight of 1.67 lb and impact velocity of 775 fps
would best represent the debris strike."

Oops:
I mistakenly said that it was an ice strike. It was foam.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Fri, 27 Oct 2017 15:53:31 +0700, John B.
wrote:

At the copper mine, in Irian Jaya, the trucks and busses that ran from
the base camp up to the tramway, that made the final jump up the mine,
were all equipped with "Jacobs Brakes" which used the engine
compression to reduce speed.

https://en.wikipedia.org/wiki/Compression_release_engine_brake
Ugh, don't remind me. I was going to college at Cal Poly, Pomona and
living in a dormitory located at the base of Kellogg Hill. Going over
the top of the hill was the San Bernardino Freeway. The slope was
steep enough that trucks had to use secondary braking to slow down. At
any hour of the day, a series of small explosions would be heard as
the trucks descended down Kellogg Hill:
https://archive.is/20130127022926/http://jake-brakes.com/about-us/noise-concerns.php
https://www.youtube.com/watch?v=a8PDO6tbVtw (first few seconds as
he slows the truck down).

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On Sunday, October 22, 2017 at 2:12:18 PM UTC-7, Ian Field wrote:
"Joerg" wrote in message
...
When researching upgrades to larger rotors I read that there may be limits
for frames and forks. Why?

Explanations were usually scant and contradictory, with some saying it
doesn't matter and some saying it does. After all, when increasing the
rotor diameter by a couple of inches the brake force on the caliper goes
down by about 30% and then due to it being positioned farther out this
should cantilever back into the same +30% into the frame or fork bosses as
before. The maximum deceleration achievable on each wheel remains the
same, until it is very close to locking up. So it should be a wash,
shouldn't it?

Bicycle brake rotors are pretty thin and fragile - the bigger you make it;
the more vulnerable it is.

Sounds like Nicki Minaj. The more you spend it, the faster it go.

At the copper mine, in Irian Jaya, the trucks and busses that ran from
the base camp up to the tramway, that made the final jump up the mine,
were all equipped with "Jacobs Brakes" which used the engine
compression to reduce speed.

https://en.wikipedia.org/wiki/Grasberg_mine

On Friday, October 27, 2017 at 7:51:11 AM UTC-7, wrote:
On Thursday, October 26, 2017 at 6:19:48 PM UTC-7, Tim McNamara wrote:
On Thu, 26 Oct 2017 13:22:07 -0400, Frank Krygowski
wrote:

And ISTM that this is yet another example of "safety inflation." For
decades and decades, cyclists rode in all weather using caliper
brakes. They removed their hands from the brake levers to shift gears..
They rode at night using halogen or even vacuum headlight bulbs
powered by dynamos, and in daylight with no lights at all. They had
shoes without custom attachments to the pedals. They wore cloth caps,
or no caps at all. They rode wearing clothing with natural,
non-blinding colors.

Now every one of those practices is portrayed by some as scandalously
risky. Sheesh!

Careful, Frank! Someone will confuse you with a conservative.

Although these days even the "new conservatives" are no longer
conservative. They're just mad that their lives suck, looking for some
payback and usually blaming the wrong people. Principled actual
conservatives are sadly becoming rara aves.

A liberal is a conservative who wants everyone every to act in such a manner so as to sooth his own conscious. He wants laws passed to force everyone else to pay for charitable causes but in such a way that he himself need not.

I'm sure you read Frank's response to a woman buying a pound and a half of hamburger for $15. "I'd tell her to shop at a different store." The soft heart of liberalism.

A liberal is someone who is responsible for your well-being: FDR (Social Security), LBJ (Medicare) and Jimmy Carter (Revenue Act of 1978/IRC 401K). Without liberals, you'd be living under a bridge. Maybe it would be a super-nice Republican bridge, but a bridge nonetheless.

-- Jay Beattie.

On 10/27/2017 4:04 PM, jbeattie wrote:
On Friday, October 27, 2017 at 7:51:11 AM UTC-7, wrote:
On Thursday, October 26, 2017 at 6:19:48 PM UTC-7, Tim McNamara wrote:
On Thu, 26 Oct 2017 13:22:07 -0400, Frank Krygowski
wrote:

And ISTM that this is yet another example of "safety inflation." For
decades and decades, cyclists rode in all weather using caliper
brakes. They removed their hands from the brake levers to shift gears.
They rode at night using halogen or even vacuum headlight bulbs
powered by dynamos, and in daylight with no lights at all. They had
shoes without custom attachments to the pedals. They wore cloth caps,
or no caps at all. They rode wearing clothing with natural,
non-blinding colors.

Now every one of those practices is portrayed by some as scandalously
risky. Sheesh!

Careful, Frank! Someone will confuse you with a conservative.

Although these days even the "new conservatives" are no longer
conservative. They're just mad that their lives suck, looking for some
payback and usually blaming the wrong people. Principled actual
conservatives are sadly becoming rara aves.

A liberal is a conservative who wants everyone every to act in such a manner so as to sooth his own conscious. He wants laws passed to force everyone else to pay for charitable causes but in such a way that he himself need not.

I'm sure you read Frank's response to a woman buying a pound and a half of hamburger for $15. "I'd tell her to shop at a different store." The soft heart of liberalism.

A liberal is someone who is responsible for your well-being: FDR (Social Security), LBJ (Medicare) and Jimmy Carter (Revenue Act of 1978/IRC 401K). Without liberals, you'd be living under a bridge. Maybe it would be a super-nice Republican bridge, but a bridge nonetheless.

"The law, in its majestic equality, forbids the rich as well as the poor
to sleep under bridges."


--
- Frank Krygowski

On Friday, October 27, 2017 at 9:39:06 AM UTC-7, Frank Krygowski wrote:
On 10/27/2017 11:06 AM, wrote:
On Friday, October 27, 2017 at 1:24:49 AM UTC-7, John B. wrote:
I've never been "doored", perhaps
because if I have to ride past a line of parked cars where a door
might be opened I either slow down or ride further enough away that a
door wouldn't hit me.

Here the bike lane can be so narrow that the car door on a two-door totally covers the lane and there's no place to dodge because passing cars will spot that and not let you out.

In my experience, the trick is to plan ahead. If I've got to move left
to avoid parked cars, etc. I tend to do it earlier rather than later.

And it may be different in other places, I suppose. (Over the years,
we've heard lots of "But the drivers HERE are really mean!") But the
shopping trip I make almost daily by bike has me leaving the store on a
street that's wide enough to share for about one block; then it gets
narrow. I stay to the right for the first part, but move left for the
narrow part. It sometimes involves looking over my shoulder at the next
motorist and signaling left to sort of negotiate; but I can't recall a
time when I wasn't allowed to merge left.

Sometimes I have to be a bit pushy. Riding in downtown Pittsburgh a few
weeks ago I came to an oddball intersection. (Pittsburgh has many.) I
had to turn right then immediately move into a left turn lane at a
traffic light.

A woman driving an SUV from the opposite direction wanted to turn left
into the same space I was using, and she tried to intimidate me into
staying at the curb. I just looked at her and kept my path, and she
stayed back.

Of course, when the light finally turned green and our ways parted, she
blared her horn. Because, you know, it was SO frustrating to have to sit
behind a bicycle, instead of being ten feet further ahead at the traffic
light!

Exactly how do you plan ahead for someone opening their door? Especially these days when people will pull over to consult their cell phones and then drive off again? And narrow bike lanes in heavy traffic always brings out the jerk in drivers. Yesterday I was almost hit by two drivers as I was pulling across a three lane into the left turn lane when there was a red light for them and they could see me crossing.

I have so much less problems with long haul truckers who know the rules and know that losing 5 seconds here means nothing.

On Thursday, October 26, 2017 at 4:50:35 PM UTC-7, Joerg wrote:
On 2017-10-26 10:43, wrote:
On Thursday, October 26, 2017 at 10:37:02 AM UTC-7, Radey Shouman wrote:
Joerg writes:

On 2017-10-24 17:21, John B. wrote:
On Tue, 24 Oct 2017 11:47:12 -0700, Joerg
wrote:

[ ... ]

The reason can be summed up in one word: Rain :-)

But last Sunday I started out my "weekend" ride in the rain. It had
been raining nearly all night and the roads had a lot of water on them
- note we have been having floods here in Bangkok lately - but it
appeared that the rain was ending so off I went.

Unfortunately my weather forecasting facility wasn't working very well
and I rode 20 Km of a 30 Km ride in light rain and flooded roads in
many places. I was splashing through water in some places and cars
were splashing through (and splashing me) in others.

Of course, Sunday is much lighter traffic then on work days but still,
Bangkok is rated as one of the cities with the most chaotic traffic
in the world, and I did have to stop suddenly several time, on flooded
roads with wet wheels and brakes.

My brakes worked just as they do in the dry. Back brake stops me
somewhat slowly and front brake stops rather suddenly, both brakes
together provides best stopping. No long wait after grabbing a brake
lever although I did think of you with your stopping problems and I
have the feeling that the brake lever pressure might be a tiny bit
more to stop in the rain but if it was it was so little that it
couldn't be quantified.

But of course I am using quality brake pads. Why it costs me US$12.12
a wheel just for pads alone.... but they do last a year or more.


It seems Californian rain and Thai rain aren't the same. When it rains
heavily and I have to do a surprise emergency stop after not having
used the brakes for a while there is 1-2sec of nada, absolutely
nothing. It makes no difference whatsoever whether I use $17
high-falutin Koolstop rain-rated pads or $4 Clarks pads. The
experience of other riders around here and in this NG is similar.

I don't understand the difference myself. When it's really raining,
meaning there's a continuous film of water on the road and a rooster
tail shooting forward off the front tire, I ride like a little old lady,
because of the delay in braking. Especially when it's dark, and leaves
and other blown down crap cover the road.


Sometimes one has to reach a destination on schedule and slowing down to
little old lady speed isn't always in the cards. That's why I prefer my
MTB on rainy days. It is slightly slower than the road bike but the
brakes are unfazed by rain. They are noisy in the rain though.


I am with you that a super strong brake hardly seems the thing you want in rain.


Not strong but I want a brake that comes on the instant I want it to,
not 1-2sec later. I also found that I can reach in much harder on my MTB
with the knobby tires in rain than I can with he slicks on the road
bike. Just not when there is a road biker right behind me ...

--
Regards, Joerg

http://www.analogconsultants.com/

Bil Cosby

On Friday, October 27, 2017 at 9:59:47 AM UTC-4, Joerg wrote:
Snipped
Oh yeah, now we have to wash out bikes after each rain ride. Standing
out there in the rain with sponge and shampoo. Great.

--
Regards, Joerg

http://www.analogconsultants.com/

Interesting that you do NOT want to do even basic maintenance/care of your bicycle. You much prefer to leave things go until something breaks ordoesn't work right; becaue it gives you something to complain about on Usenet.

Sheesh!

Cheers