Bicycle Stopping Distances

"Howard Kveck" wrote in message
...

Which is one of the reasons Campy has a dual pivot brake (clamps hard
for good
braking) for the front and a single pivot one for the rear. The rear
doesn't do that
much and you simply don't need that much braking power on the rim in the
back.

(Eyes rolling!)

On Nov 5, 9:13*pm, MagillaGorilla wrote:
RicodJour wrote:
On Nov 5, 7:11*pm, MagillaGorilla wrote:

Those 2 cyclists who ran into Dr. Thompson are ****ing spazzes.

You mean Mrs. New Bitch Thompson.


I love how you talk up a big game about "justice" and then laugh about
prison rape. *And then you think this makes you look intelligent.

Years ago my mother used to say to me, she'd say, "In this world,
Elwood, you must be" - she always called me Elwood - "In this world,
Elwood, you must be oh so smart or oh so pleasant." Well, for years I
was smart. I recommend pleasant. You may quote me.
- Elwood P. Dowd

I do not think a little prison time is adequate for Dr. PLEASE Use
Some Lube Thompson. I think having his hemorrhoids hammered would
knock some sense into him, and leave him with some scars - that's
justice. I'm more biblical, and slightly more twisted, than most -
and just honest about it, with which you seem to have some difficulty.

R

In article ,
"Tom Kunich" wrote:

"Howard Kveck" wrote in message
...

Which is one of the reasons Campy has a dual pivot brake (clamps hard
for good
braking) for the front and a single pivot one for the rear. The rear
doesn't do that
much and you simply don't need that much braking power on the rim in the
back.

(Eyes rolling!)

I see you're going to read that post and sneeringly respond to it yet ignore the
one where you were asked to post a link to one of Iran's leaders saying they wanted
to drop nuclear weapons on Israel. What a dork.

--
tanx,
Howard

Caught playing safe
It's a bored game

remove YOUR SHOES to reply, ok?

" wrote:

On Nov 5, 5:23*pm, MagillaGorilla wrote:
" wrote:
On Nov 4, 5:29*am, MagillaGorilla wrote:
" wrote:

BTW, the 0.6 g number isn't magical, it's just based
on the angle from your center of mass to the front
contact patch. *If the center of mass is around your
belly button, then (on my bike) the height off the ground
is about 1.2 m and the horizontal distance to the
contact patch is about 0.75 m. *The geometry of the
opposing torques from deceleration and gravity means
that the bike starts to endo when the deceleration is
more than (0.75/1.2) ~ 0.63 g. *All fairly approximate.

Ben

Hey dumbo,

In a maximum braking effort, you transfer your weight as far back and as low as
possible. *You bury your head into your stem...you even your pedals so no leg is
higher than it has to be....you push your entire center of mass down into your
top tube. *All of this is done instinctually and in a fraction of a second. *So
all your numbers are wrong.

What you are talking about is the physics of how a ****ing Cat. 5 girl brakes her
bike on the Saulsalito Kenny Pap Smear group ride and then crashes into 6 riders
in front of her while claiming she "couldn't stop in time."

That's not how I stop my bike if I need to dig deep into the pro suitcase of
courage.

In fact, I would say a good proportion of maximum braking effort comes not from
how hard or quick you pull on the brake levers, but how quickly, how low, and how
rearward you shift your weight.

Your equation treats one of the most important aspects of maximum braking (i.e.
the lowering and shifting of center of mass rearward) as being a constant instead
of a rather large variable. *That's the fundamental mistake of your equation.

You wrote the equation for how Liz Hatch stops her bike, and not for how the
monkey stops his bike.

QID.

Christ, man, you ought to be ashamed of yourself.
This is so lame the Union of Face-Ripping Chimps
Internationale is thinking of kicking you out because they've
finally figured out you're just a soft-fingered human.

Putting your head down is for sprinting into giant
Coke cans, not for maximum braking. *Any extra
braking effect is purely psychological, like closing
your eyes as you're about to hit a bump. *Throwing your
weight back actually momentarily pushes the bike
forward. *For ****'s sake, even George Hincapie knows
that - it's how he won Gent-Wevelgem by a fractional
tire width, throwing the bike in the sprint.

Go play your tuba and ride over Cat 5 girls' necks
with your stopping technique.

Ben
My new stopping technique is unstoppable.

No asswipe. *Putting your head down lowers your center of gravity, and shifting your
weight rearward helps put more weight over your rear tire and allows for your front
brake to be gabbed harder before it will flip you. *It also helps make your rear brake
more effective.

It's a physics equation, jackass. *Has nothing to do with my opinion. *Where did you
go to college with that kind of attitude?

Soft-fingered human,

What you were arguing is that the dynamic effect
of shifting your body - what you referred to as "the shifting
of center of mass ... being a rather large variable" -
is important. That's clearly BS because the dynamic
effect of shifting your weight back is to push the bike
forward, as in throwing your bike in a sprint.

Yes, I am aware of the Law of physics you point out (every reaction has an opposite and
equal reaction). Several things.... the CoG movement is more downward than rearward. Your
butt should never leave your seat because doing so would take weight off your rear wheel
that is transfered down through the seat stays (this helps prevent your rear wheel from.
In a bike throw (a slightly different movement), you allow yourself to completely slide off
the seat.

Second, the reason why you should still do this despite its known negative "slight bike
throw" effect that you point out is because the GAIN you get from your weight being shifted
rearward and lower is increased braking by an amount that offsets the loss from the
modified bike throw reaction. A bike throw only lasts a fraction of a second, but the
braking moment is 4-10 times that in length of time. And once your body is stationary and
rearward, the bike throw moment disappears and you will gain many feet in braking (perhaps
20-50?). And what's the loss from a modified bike throw...say 1-2 feet? So 40-2 feet = 38
feet gain in stoppage.

You people do the same thing when you talk about turns in a velodrome - you can't talk
about 1 physics effect in a turn while ignoring more significant ones. I am not sure what
the proportion of effect is from lowering your body weight vs. shifting it rearward. All I
know is you should do both. And if you plug that into the physics equation for a bike, it
will quantify it for you.

So when you are doing a max brake effort, you should immediately kiss the stem (go lower if
you can and push your trunk into your top tube) and lock your arms out in your drops while
pushing your butt as far back on the saddle as you can. It should resemble a bike throw
except you butt will never leave the saddle and you are of course grabbing the brakes.





Further,
the entire braking effort as you slide to a panic stop
takes longer than the body shift, so for most of the
braking time your body position is pretty static, as
far back as you can get. We just have to consider the
static effect of shifting your position.

Correct...once your body is static, the bike throw reaction disappears and you get the gain
from your CoG being lower and rearward throughout the duration of the braking.



Putting your head down shifts your center of mass
hardly at all, unless you are shaped like a bobble-head
doll.

Not true. I said to shift your entire upper body downward - head shoulders, torso... your
face should be buried into the steam and your chest should be trying to mate with the top
tube. Imagine a time trial position where you are going 150 mph downhill and you want
minimal wind resistance. That's the position you want.


It's purely psychological.

You spelled physics wrong.



Shifting your weight
rearward helps but by only 10 cm or so, because
you can't get any further back unless your bars are
set up way too close to the saddle.

I'd say about 6 inches rearward is about the most you're gonna get, correct. This is
really for high speed descent stops. But if you are doing a road race or training ride
with 55 mph long descents like Gila you should definitely be using a larger stem reach
anyway (say +4 cm over a cri bike) to aid not only for emergency braking, but for
aerodynamic tucks.



Having your weight
rearward is important but your rear brake still doesn't
do much in a panic stop. Grab it anyway, but don't
expect it to do anything as all your weight shifts to
the front.

The rear brake does about 30% of your stopping whether you like it or not. It will do that
30% more effectively if you shift your weight rearward.



It's funny you speak of physics equations. Write the
equation down so we can see.

You're gonna make me break out the physics books from college that have been collecting
dust? Geez...I dunno man. I would do it if you looked like Petra Nemcova. Do you look
like her? You can even be a tranny - I don't give a ****.



As for my attitude, I didn't get it in college.
I got it in Airco Technical Monkey-Shaming Institute.

Ben

Magilla

Howard Kveck wrote:

In article ,
" wrote:

Having your weight
rearward is important but your rear brake still doesn't
do much in a panic stop. Grab it anyway, but don't
expect it to do anything as all your weight shifts to
the front.

Which is one of the reasons Campy has a dual pivot brake (clamps hard for good
braking) for the front and a single pivot one for the rear. The rear doesn't do that
much and you simply don't need that much braking power on the rim in the back.

--
tanx,
Howard

Caught playing safe
It's a bored game

remove YOUR SHOES to reply, ok?

If you really want to increase the effectiveness and stability of your rear brake, you
should mount it to the frame on the FRONT of your seat stays, which is how your front
brake is mounted with respect to the rotation of the rim. What this does is cause the
brake caliper assembly to be pushed into the frame during the entire braking event.
But in standard rear brake mounts, the caliper's entire stability is only by the
mounting bolt and the caliper is bring pulled away from the frame.

Mounting your rear calipers to the front of the rear seat stays will aid in high speed
braking stability by a couple percent. The only reason it's not done like that for
most riders is because of aesthetics. Any mechanic or frame builder will tell you it's
not as good to mount the brake calipers where 99.99% of the people mount it.

Magilla

On Nov 6, 8:04*am, MagillaGorilla wrote:
Howard Kveck wrote:
In article ,
" wrote:

*Having your weight
rearward is important but your rear brake still doesn't
do much in a panic stop. *Grab it anyway, but don't
expect it to do anything as all your weight shifts to
the front.

* *Which is one of the reasons Campy has a dual pivot brake (clamps hard for good
braking) for the front and a single pivot one for the rear. The rear doesn't do that
much and you simply don't need that much braking power on the rim in the back.

--
* * * * * * * * * * * * * * * tanx,
* * * * * * * * * * * * * * * *Howard

* * * * * * * * * * * * *Caught playing safe
* * * * * * * * * * * * * It's a bored game

* * * * * * * * * * *remove YOUR SHOES to reply, ok?

If you really want to increase the effectiveness and stability of your rear brake, you
should mount it to the frame on the FRONT of your seat stays, which is how your front
brake is mounted with respect to the rotation of the rim. *

That is not why a front brake is mounted in front of the fork.

What this does is cause the
brake caliper assembly to be pushed into the frame during the entire braking event.

That's not what's happening on the front brake, or the rear brake if
you move it to the front of the frame.

But in standard rear brake mounts, the caliper's entire stability is only by the
mounting bolt and the caliper is bring pulled away from the frame.

If there is a single mounting bolt, the same thing is happening
wherever the brake is located.

Mounting your rear calipers to the front of the rear seat stays will aid in high speed
braking stability by a couple percent. *The only reason it's not done like that for
most riders is because of aesthetics. *Any mechanic or frame builder will tell you it's
not as good to mount the brake calipers where 99.99% of the people mount it.

No, they won't tell you that - at least not for the reasons you
state. Your numbers are wrong, your theory is wrong, and your logic
curiously absent.

Stick to the dodging and weaving. It's what you do best.

R

On 6 Nov, 13:04, MagillaGorilla wrote:

If you really want to increase the effectiveness and stability of your rear brake, you
should mount it to the frame on the FRONT of your seat stays, which is how your front
brake is mounted with respect to the rotation of the rim. *What this does is cause the
brake caliper assembly to be pushed into the frame during the entire braking event.
But in standard rear brake mounts, the caliper's entire stability is only by the
mounting bolt and the caliper is bring pulled away from the frame.

Mounting your rear calipers to the front of the rear seat stays will aid in high speed
braking stability by a couple percent. *The only reason it's not done like that for
most riders is because of aesthetics. *Any mechanic or frame builder will tell you it's
not as good to mount the brake calipers where 99.99% of the people mount it.

Magilla

Huh? If anything you want the front brake behind the mounting so
that with typical rims which have a slight flare to their extremity
the brake pads will move towards the hubs so providing a more
controllable inverse servo. The negative servo effect already exists
with the rear brake and the consequences of a diving rear brake, with
the caliper jamming the tyre, are likely of little concern. Mudguards
will prevent wheel jamming with brake mount failure.

thirty-six wrote:
On 6 Nov, 13:04, MagillaGorilla wrote:

If you really want to increase the effectiveness and stability of your rear brake, you
should mount it to the frame on the FRONT of your seat stays, which is how your front
brake is mounted with respect to the rotation of the rim. What this does is cause the
brake caliper assembly to be pushed into the frame during the entire braking event.
But in standard rear brake mounts, the caliper's entire stability is only by the
mounting bolt and the caliper is bring pulled away from the frame.

Mounting your rear calipers to the front of the rear seat stays will aid in high speed
braking stability by a couple percent. The only reason it's not done like that for
most riders is because of aesthetics. Any mechanic or frame builder will tell you it's
not as good to mount the brake calipers where 99.99% of the people mount it.

Magilla

Huh? If anything you want the front brake behind the mounting so
that with typical rims which have a slight flare to their extremity
the brake pads will move towards the hubs so providing a more
controllable inverse servo. The negative servo effect already exists
with the rear brake and the consequences of a diving rear brake, with
the caliper jamming the tyre, are likely of little concern. Mudguards
will prevent wheel jamming with brake mount failure.

You're my new hero.

Fred Fredburger wrote:

thirty-six wrote:
On 6 Nov, 13:04, MagillaGorilla wrote:

If you really want to increase the effectiveness and stability of
your rear brake, you should mount it to the frame on the FRONT of
your seat stays, which is how your front brake is mounted with
respect to the rotation of the rim. What this does is cause the
brake caliper assembly to be pushed into the frame during the entire
braking event. But in standard rear brake mounts, the caliper's
entire stability is only by the mounting bolt and the caliper is
bring pulled away from the frame.

Mounting your rear calipers to the front of the rear seat stays will
aid in high speed braking stability by a couple percent. The only
reason it's not done like that for most riders is because of
aesthetics. Any mechanic or frame builder will tell you it's not as
good to mount the brake calipers where 99.99% of the people mount
it.

Magilla

Huh? If anything you want the front brake behind the mounting so
that with typical rims which have a slight flare to their extremity
the brake pads will move towards the hubs so providing a more
controllable inverse servo. The negative servo effect already
exists with the rear brake and the consequences of a diving rear
brake, with the caliper jamming the tyre, are likely of little
concern. Mudguards will prevent wheel jamming with brake mount
failure.

You're my new hero.


And you always claimed skills learned in rbt would never be applicable
anywhere else.

--
Bill Asher

William Asher wrote:
Fred Fredburger wrote:

thirty-six wrote:
On 6 Nov, 13:04, MagillaGorilla wrote:

If you really want to increase the effectiveness and stability of
your rear brake, you should mount it to the frame on the FRONT of
your seat stays, which is how your front brake is mounted with
respect to the rotation of the rim. What this does is cause the
brake caliper assembly to be pushed into the frame during the entire
braking event. But in standard rear brake mounts, the caliper's
entire stability is only by the mounting bolt and the caliper is
bring pulled away from the frame.

Mounting your rear calipers to the front of the rear seat stays will
aid in high speed braking stability by a couple percent. The only
reason it's not done like that for most riders is because of
aesthetics. Any mechanic or frame builder will tell you it's not as
good to mount the brake calipers where 99.99% of the people mount
it.

Magilla
Huh? If anything you want the front brake behind the mounting so
that with typical rims which have a slight flare to their extremity
the brake pads will move towards the hubs so providing a more
controllable inverse servo. The negative servo effect already
exists with the rear brake and the consequences of a diving rear
brake, with the caliper jamming the tyre, are likely of little
concern. Mudguards will prevent wheel jamming with brake mount
failure.
You're my new hero.


And you always claimed skills learned in rbt would never be applicable
anywhere else.


RBT? I thought he was channeling old Star Trek episodes. The "negative
servo" and "inverse servo" are things that should be said just prior to
"reversing the polarity". Does Scotty hang out in RBT?