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

On Friday, October 27, 2017 at 5:42:18 PM UTC-7, John B. wrote:
On Fri, 27 Oct 2017 08:06:33 -0700 (PDT), wrote:

On Friday, October 27, 2017 at 1:24:49 AM UTC-7, John B. wrote:
On Thu, 26 Oct 2017 13:37:00 -0400, 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.

I suspect that may be the secret. 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.

If the choice is to run into a car door or be run over by a car then I
think I'd get off and walk. After all, running into a door, in the
litigatious society that you live in would likely result in a court
case that would beggar anyone living on a $500 a month retirement.

If spilling a cup of coffee in your lap is worth $2.8 million what is
the terror and delayed stress of some fiend on a bicycle coming out of
nowhere and smashing into your door just as you are trying to get
out.... Look, Look, there is the scar, right there on my arm and I
haven't had a good night's sleep since! The "partner" might even file
a co-suite for loss of connubial rights for the period he/she/it was
under treatment.

One could always assume like ridesolittle that these doors are slung open while you are a half mile away so that you can plan. Or that people do not purposely drive directly on the line of the bicycle lane when the center lane is free.

I drove up to Sacramento yesterday (125 miles one way). I drive the speed limit and there wasn't hardly a car I encountered on the way up doing the same. Even the heavy trucks were doing a minimum of 10 mph over the limit which meant that I would very slowly approach them in the slow lane as the little rises here and there or a wind gust would slow them a bit. The normal traffic was going 80 mph. Even over broken pavement which was bouncing your wheels off of the ground. They were vying to pass one another to the point that they were endangering themselves and others on the road. If I pulled into the #2 lane to go around a truck you could watch in the rear view mirror as cars would pull from the #1 lane into the #2 lane and drive right up to less than a car length behind you, violently swerve to the left accelerate around and swerve violently to the right less than a car length in front of me. In one case the speed limit increased to 70 and so did I and so did the doubles. There was a large open space as I approached the truck so I pulled over to pass him. You could SEE the traffic speed up behind me and some jerk in a van came right up on my rear bumper and started flashing his lights continuously. When I cleared the truck safely I pulled over and this moron came sailing past pulled in front of me and exited the freeway.

After the piano recital I left Sacramento about 10 pm on highway 80 towards San Francisco. This was before the bars let out but everyone was driving as if they were three sheets to the wind. I have a Ford Taurus which is a full sized sedan so it is pretty damn stable. In one spot I was passed by a car doing what I would guess to be well over 120 mph. He was so close to me as he passed in the #4 lane and I was in the #3 to avoid cars entering the freeway that my car was pushed physically over by the wind envelope of his car. Since he was going that fast there were several others trying to keep up. One "economy" car could only do around 100 mph so he made up for it by cutting around the others going a mere 80 mph.

I saw one Highway Patrol. He was pulled over to the side of the road obviously calling a tow truck to bring gas out to some guy who had run out. This is all the CHP does anymore. They do NOT pass out traffic tickets. They do not interfere in the speed contests. They don't even try to stop the freeway shootings that occur in the same stretches of highway over and over.

This is the California of the liberals.

On Friday, October 27, 2017 at 5:48:25 PM UTC-7, John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....

I am somewhat puzzled as well. Off-road and especially with the rather immense weight of Joerg's full suspension I can understand the disks since you could bend the rims inwards with the forces you have to apply to slow on very steep terrain at high speeds. But road bikes?

Two days ago as I returned home I crossed a patch of concrete and then grass. I found myself having to pump the skeleton brakes because they were so powerful they were about to lock the wheels even on the concrete. Why in heavens name would I need a disk? And why would you EVER ride on the streets in such a manner that the half second it takes to clear water from the front of the brake shoe would be the difference between having an accident and not?

On Friday, October 27, 2017 at 5:55:22 PM UTC-7, Frank Krygowski wrote:
On 10/27/2017 5:40 PM, wrote:
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?

I don't ride in a door zone. Ever.

So you don't ride in the bike lanes. Virtually all but the very newest are in the door zone.

On Friday, October 27, 2017 at 6:04:58 PM UTC-7, Frank Krygowski wrote:
On 10/27/2017 8:42 PM, John B. wrote:
On Fri, 27 Oct 2017 08:06:33 -0700 (PDT), wrote:

On Friday, October 27, 2017 at 1:24:49 AM UTC-7, John B. wrote:
On Thu, 26 Oct 2017 13:37:00 -0400, 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.

I suspect that may be the secret. 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.

If the choice is to run into a car door or be run over by a car then I
think I'd get off and walk.

In practice, at least in my experience, the actual choice is between the
_risk_ of getting hit by an opening door, and the _risk_ of a motorist
deliberately running me over from behind.

In my experience, the latter risk is almost zero. Consider, we're almost
certainly talking about a place where there are witnesses, because the
situation requires people parking, getting out of their cars, opposing
traffic that would prevent the guy behind from changing lanes, etc.
There just aren't that many psychopaths who would risk prison terms by
deliberately running you over, especially because it would slow them down.

On the other hand, the person doing the dooring doesn't have to be a
psychopath. He just has to be inattentive. There are lots and lots of
those people.

Now, for corroboration: I have definitely had situations where a door
popped open, and I would have been doored if I had been riding within
reach. But while I've occasionally (but rarely) had motorists honk or
yell when I claim a lane, I've never had one run me over.

And let's remember that dooring can be fatal. If the door snags your
right handlebar, the bike whips to the right and you are instantaneously
thrown to the left, directly into the path of the cars you were so
worried about.

Where would these witnesses come from? The cars that simply continued driving?

On 10/29/2017 10:52 AM, wrote:
On Friday, October 27, 2017 at 5:42:18 PM UTC-7, John B. wrote:
On Fri, 27 Oct 2017 08:06:33 -0700 (PDT), wrote:

On Friday, October 27, 2017 at 1:24:49 AM UTC-7, John B. wrote:
On Thu, 26 Oct 2017 13:37:00 -0400, 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.

I suspect that may be the secret. 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.

If the choice is to run into a car door or be run over by a car then I
think I'd get off and walk. After all, running into a door, in the
litigatious society that you live in would likely result in a court
case that would beggar anyone living on a $500 a month retirement.

If spilling a cup of coffee in your lap is worth $2.8 million what is
the terror and delayed stress of some fiend on a bicycle coming out of
nowhere and smashing into your door just as you are trying to get
out.... Look, Look, there is the scar, right there on my arm and I
haven't had a good night's sleep since! The "partner" might even file
a co-suite for loss of connubial rights for the period he/she/it was
under treatment.

One could always assume like ridesolittle that these doors are slung open while you are a half mile away so that you can plan. Or that people do not purposely drive directly on the line of the bicycle lane when the center lane is free.

I drove up to Sacramento yesterday (125 miles one way). I drive the speed limit and there wasn't hardly a car I encountered on the way up doing the same. Even the heavy trucks were doing a minimum of 10 mph over the limit which meant that I would very slowly approach them in the slow lane as the little rises here and there or a wind gust would slow them a bit. The normal traffic was going 80 mph. Even over broken pavement which was bouncing your wheels off of the ground. They were vying to pass one another to the point that they were endangering themselves and others on the road. If I pulled into the #2 lane to go around a truck you could watch in the rear view mirror as cars would pull from the #1 lane into the #2 lane and drive right up to less than a car length behind you, violently swerve to the left accelerate around and swerve violently to the right less than a car length in front of me. In one case the speed limit increased to 70 and so did I and so did the doubles. There w
as a large open space as I approached the truck so I pulled over to pass him. You could SEE the traffic speed up behind me and some jerk in a van came right up on my rear bumper and started flashing his lights continuously. When I cleared the truck safely I pulled over and this moron came sailing past pulled in front of me and exited the freeway.

After the piano recital I left Sacramento about 10 pm on highway 80 towards San Francisco. This was before the bars let out but everyone was driving as if they were three sheets to the wind. I have a Ford Taurus which is a full sized sedan so it is pretty damn stable. In one spot I was passed by a car doing what I would guess to be well over 120 mph. He was so close to me as he passed in the #4 lane and I was in the #3 to avoid cars entering the freeway that my car was pushed physically over by the wind envelope of his car. Since he was going that fast there were several others trying to keep up. One "economy" car could only do around 100 mph so he made up for it by cutting around the others going a mere 80 mph.

I saw one Highway Patrol. He was pulled over to the side of the road obviously calling a tow truck to bring gas out to some guy who had run out. This is all the CHP does anymore. They do NOT pass out traffic tickets. They do not interfere in the speed contests. They don't even try to stop the freeway shootings that occur in the same stretches of highway over and over.

This is the California of the liberals.



The policeman isn't there to create disorder;
the policeman is there to preserve disorder.
- Mayor Richard J. Daley

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On 10/29/2017 11:02 AM, wrote:
On Friday, October 27, 2017 at 6:04:58 PM UTC-7, Frank Krygowski wrote:
On 10/27/2017 8:42 PM, John B. wrote:
On Fri, 27 Oct 2017 08:06:33 -0700 (PDT), wrote:

On Friday, October 27, 2017 at 1:24:49 AM UTC-7, John B. wrote:
On Thu, 26 Oct 2017 13:37:00 -0400, 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.

I suspect that may be the secret. 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.

If the choice is to run into a car door or be run over by a car then I
think I'd get off and walk.

In practice, at least in my experience, the actual choice is between the
_risk_ of getting hit by an opening door, and the _risk_ of a motorist
deliberately running me over from behind.

In my experience, the latter risk is almost zero. Consider, we're almost
certainly talking about a place where there are witnesses, because the
situation requires people parking, getting out of their cars, opposing
traffic that would prevent the guy behind from changing lanes, etc.
There just aren't that many psychopaths who would risk prison terms by
deliberately running you over, especially because it would slow them down.

On the other hand, the person doing the dooring doesn't have to be a
psychopath. He just has to be inattentive. There are lots and lots of
those people.

Now, for corroboration: I have definitely had situations where a door
popped open, and I would have been doored if I had been riding within
reach. But while I've occasionally (but rarely) had motorists honk or
yell when I claim a lane, I've never had one run me over.

And let's remember that dooring can be fatal. If the door snags your
right handlebar, the bike whips to the right and you are instantaneously
thrown to the left, directly into the path of the cars you were so
worried about.

Where would these witnesses come from? The cars that simply continued driving?


Right, it's 2017 America where 'nobody seen nuffin.' not to
mention, 'snitches get stitches.'

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On Friday, October 27, 2017 at 6:13:58 PM UTC-7, Ralph Barone wrote:
John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....
--
Cheers,

John B.

As far as I can tell, the differences between a rim brake and a 622 mm disk
a

1) The disk doesn't have to provide tire clearance, so the pads can sit
closer, facilitating higher mechanical advantage.

2) The disk is not connected to the rim, so it doesn't bend and warp when
you hit a pothole. Again, the pads can sit closer and have higher MA.

3) The disk doesn't thermally couple to the tire, so no blowouts on long
descents.

4) The disk is solid, so there's less flexing when you squeeze it with the
pads.

1) there is no such thing as a 622 mm disk. And there would be insufficient fork clearance on any bike including cross bikes.

2) While the disk is not attached to the rim what gives you the idea that the spokes stretch or bend? Especially modern wheels are virtually a rigid structure.

3) And you can see disks distort when one pad wears out which is pretty rapidly. Deep grooves are worn into the disk pretty rapidly in these cases. There is simply insufficient room for a deep enough pad to get reasonable wear characteristics.

4) The disks aren't solid anymore. They are drilled and grooved and the inside diameter is reduced to the usable minimum. The carriers are aluminum and it is possible to actually melt the carrier on a racer.

As everything else there are advantages and disadvantages but the fact remains that almost all of the advantages are over-ridden by the fact that they are nothing more than marketing.

On Friday, October 27, 2017 at 8:17:45 PM UTC-7, Joy Beeson wrote:
On Fri, 27 Oct 2017 06:59:56 -0700, Joerg
wrote:

Oh yeah, now we have to wash out bikes after each rain ride. Standing
out there in the rain with sponge and shampoo. Great.

You don't have a garden hose?

Back when I could ride after the outside faucets had been turned off
for the winter, I used to hose salt and ice off my bike by filling my
water bottles with hot tap water, reserving the first squirt from each
bottle to get under the fenders. I don't think I ever had to make
more than two trips into the house for more water.

Come to think of it, I don't think I ever hosed it in the summer
(except when cleaning the braking surfaces, of course), because I rode
only on pavement. There was one mile of gravel road in an adjacent
county, but the grader wore out and it was cheaper to pave the road
than to buy a new grader.

Yes Joy, but you're a lady and ladies are neat. Except for my wife, the hoarder.

On Friday, October 27, 2017 at 8:54:45 PM UTC-7, Ralph Barone wrote:
John B. wrote:
On Sat, 28 Oct 2017 01:13:54 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....
--
Cheers,

John B.

As far as I can tell, the differences between a rim brake and a 622 mm disk
a

1) The disk doesn't have to provide tire clearance, so the pads can sit
closer, facilitating higher mechanical advantage.

I'm not sure that is correct. After all some old Greek guy was
supposed to have said, "Give me a lever and a place to stand and I
will move the earth". Nothing about being close.

No. I'm pretty certain I'm right here. Let's say that you can pull 100 lbs
on your brake lever and the lever has 2" of play before it hits your bars.
You can fiddle with leverage many places in the system, but the product of
that initial 100 lbs and 2" will be constant in the system. If the final
travel of the brake pads is 1/2", then you can apply 400 lbs force to the
pads. If you tighten up your tolerances such that the pads only have to
move 1/16", then you can increase the leverage to the point where you can
apply 3200 lbs force to the pads. In disk brake systems this reduction in
pad-disk distance allow the MA to be increased to compensate for the
decreased leverage of the disk on the wheel. The increases brake pad
pressure at a given bike deceleration is what gives disk brakes misread
consistent performance in the wet.

But the leverage includes the respective diameters of the wheel and disk which actually reduces the STOPPING power of the wheel and also puts a hell of a lot more strain on the spokes.

John B. wrote:
On Sun, 29 Oct 2017 05:11:13 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sun, 29 Oct 2017 01:45:50 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 15:12:37 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 06:23:59 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 03:54:43 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Sat, 28 Oct 2017 01:13:54 +0000 (UTC), Ralph Barone
wrote:

John B. wrote:
On Fri, 27 Oct 2017 09:32:04 -0700, Joerg
wrote:

On 2017-10-27 09:25, Frank Krygowski wrote:
On 10/27/2017 9:58 AM, Joerg wrote:

Finally after many decades the bicycle industry woke up and adopted
what the automotive guys had all along, disc brakes. Why should I
accept an inferior brake system on a new bike when there is a much
better one?

sigh There are advantages and disadvantages to this equipment choice,
just as with other equipment choices. The disadvantages of discs have
been discussed. If they don't matter or apply to you, fine; but they
matter to others.


Many others just don't know any better. I have witnessed several people
riding a bike with hydraulic disc brakes for the first time and the
reaction was usually "WHOA!". Same with me, it almost sent me over the bar.


But I'll note that you're currently in a project to increase your disc's
diameter from something like 160mm or 180mm up to 200mm or more. You
seem to feel bigger diameter is better.


Because bigger is better here.


Well, even "better," why not go up to roughly 622mm? That's what lots
of us prefer, with cable actuation.


The disadvantages have been discussed ad nauseam. A rim brake is not a
disc brake. Not even close.

Care to explain the mechanical difference? I mean a rotating surface
and two friction pads that are tightened against it....
--
Cheers,

John B.

As far as I can tell, the differences between a rim brake and a 622 mm disk
a

1) The disk doesn't have to provide tire clearance, so the pads can sit
closer, facilitating higher mechanical advantage.

I'm not sure that is correct. After all some old Greek guy was
supposed to have said, "Give me a lever and a place to stand and I
will move the earth". Nothing about being close.

No. I'm pretty certain I'm right here. Let's say that you can pull 100 lbs
on your brake lever and the lever has 2" of play before it hits your bars.
You can fiddle with leverage many places in the system, but the product of
that initial 100 lbs and 2" will be constant in the system. If the final
travel of the brake pads is 1/2", then you can apply 400 lbs force to the
pads. If you tighten up your tolerances such that the pads only have to
move 1/16", then you can increase the leverage to the point where you can
apply 3200 lbs force to the pads. In disk brake systems this reduction in
pad-disk distance allow the MA to be increased to compensate for the
decreased leverage of the disk on the wheel. The increases brake pad
pressure at a given bike deceleration is what gives disk brakes more
consistent performance in the wet.

Movement of the parts doesn't make any difference the efficiency is
the pressure applied to the brake lever versus the pressure applied to
the braking device, usually the pads themselves.

A lever that is 1 foot long and moves, lets say, one quarter of the
diameter of a 2 foot circle applies the same force to a load located 1
foot from the fulcrum as a 100 ft lever which moves 1/4 of the
diameter of a 200 ft circle applies to a load that is 100 ft. from the
fulcrum. The first lever moves 19 inches and the second moves 157
feet.

Sure. But the distance you can move your brake lever is limited by the
length of your fingers, and so the distance you can move at the lever end
is essentially fixed. To increase the mechanical advantage in THAT system,
you have to reduce the distance the brake pads move. No ifs, ands, buts or
maybes.

You are talking about two different things. Mechanical efficiency and
how long your fingers are.

They aren't really related.
--
Cheers,

John B.

Theoretically, the mechanical advantage of a brake system and the length of
your fingers aren't related, but practically, in this example of the
mechanical advantage of a bicycle brake system, the two quantities are
chained together at the ankles. You can't have high brake pad travel and
high mechanical advantage unless the travel of the brake lever is very
large, and human hand dimensions just won't allow that.

Well you can continue to equate mechanical advantage with long, or
short, fingers but it doesn't make it true :-)

But you keep talking about the large clearance between the rim brake
pads and the rim versus the disc pads and the disc which isn't
necessarily true.

I use brifters - Shimano STI brake&shifters - on two of my bikes and
considering the rather limited travel of the brake levers the pads
need to be fitted very closely to the rims, and of course, the rims
need to be very straight. The two bikes are about 1,000 km from where
I'm presently located so I'm going much by memory but I think that the
pad to rim clearance is about 1mm. The two bikes I have here both have
down tube shifting and the brake pad clearance is largely determined
by where I want the brake levers to be when the brakes are applied,
but measuring one bike shows that the clearance is about 6mm.

I can sense no appreciable difference in the pressure I feel against
my fingers when stopping any of the four bikes.
--
Cheers,

John B.

I think we're pretty close to a standoff here, so I'll invoke the name of
Sheldon, and then give up. Read through

https://www.sheldonbrown.com/cantilever-geometry.html

and tell me if it changes your opinion about what I've been saying.

To summarize my position
1) The mechanical advantage of a brake system (ie: the ratio of pad force
to lever force) is the inverse of the ratio of pad travel to lever travel.

2) bike brakes are made for humans and not orangutans or aliens, so they
all tend to have about the same amount of lever travel.

3) because of 1 and 2, the travel of the brake pad is pretty much inversely
proportional to the mechanical advantage.

4) because of 1, 2 and the fact that brakes need to actually touch the
rim/disk in order to work, the mechanical advantage of a bicycle brake
system is approximately inversely proportional to how far you can set the
pads away from the rim/disk and still have the system work (non-linear
systems excepted).

If you still doubt what I say, you may have to continue the discussion with
somebody else, as I have obviously failed in my attempts to communicate.


Yes, Sheldon says just what I've been saying that mechanical advantage
is the relationship between force in and force out and he describes
it, as I did, two ways. One as a ratio of forces and two a ratio of
distances. i.e., a lever that has a ratio of two to one will exert
twice the force on the shorter end as applied to the longer end and by
the same token that the long end will travel twice as far as the short
end.

It has nothing to do with finger length or brake pad clearance.
--
Cheers,

John B.

Theoretically, yes, but practically, no. Try to design a brake system with
a 10:1 mechanical advantage and 1" of brake pad travel and you will soon
discover that your fingers are about 8" too short for it to work because
you will have to pull 10" at the lever.

So yeah, theory says nothing about finger length, but pretty much every
brake lever out there doesn't move more than about 3". Therefore,
practically, the travel of your brake pads can't be any more than 3"
divided by your MA.

So then, if you NEED or WANT a certain amount of brake pad to rim
clearance, then that sets a practical limit on the MA you can have in that
system before you run out of lever travel.

For a real world example, I have cantilever brakes on my Surly. I can lower
the straddle cable to increase the MA of the system, but then I get lower
pad travel. To ensure that I don't bottom out my levers while braking, I
then have to keep the pads closer to the rim. However, I can't just keep
doing that forever, since I also have to accommodate runout and warpage in
my rim. I also need to maintain a certain pad to rim distance to allow me
to unhook the straddle cable so that I can remove my wheel. If I was
running a disk setup, my minimum pad to disk clearance would be smaller,
which would allow the use of a brake system with higher MA. I can't
consider MA and pad to disk/rim clearance independently because I have
normal human fingers that only allow 3" or less of lever travel. And
that's how finger length becomes part of the equation.

The point is that the mechanical advantage of a lever system is
determine by the relative lengths of the levers. A 2::1 mechanical
advantage remains a 2::1 mechanical advantage regardless of what is
attached to it... just as I've been saying.

Yes, I agree with that.

You seem to be arguing that because you have short fingers that
somehow the mechanical advantage of the brake lever changes in some
way. But in fact, if you take the brake lever off the handlebar and
throw it in the "spares" box the mechanical advantage of that brake
lever hasn't changed a bit.

No, that's not the point I'm arguing. I'm not saying that the MA is
determined by the length of your fingers. What I'm saying is that lever
pull (which is constrained by finger length) and pad travel (which may be
constrained by other requirements) are connected to each other by MA.
Therefore, if you are designing a real world braking system, you can't
independently chose your desired MA and your desired pad travel, because
the product of the two equals your lever travel, which is practically
limited to around 3" by the length of human fingers.


--
Cheers,

John B.