if you wanted maximum braking, where would you sit?

I find the idea position changes depending on speed and deaccelleration
while breaking.
So, that means it's constantly changing...
It's hard to put into words actually, so I'm trying to think about it..

Yes, a force vector diagram is the clearest way to see the problem.

First of all, I wouldn't "sit" anywhere. I"d definately get out of the
saddle, but I'd stay very low. I'd apply the breaks lightly and fairly
evenly with more front than rear. Then, I'd increase pressure and the
faster I de accellerate the farther I'd slide my ass (which is still off the
seat) rearwards. Under the heaviest breaking, Ideally my weight would
probably want to be above the rear axle althought I doubt I could get it
that far back on even ground.

You meant, "apply the brakes", right?
No, you can't get your center of mass anywhere near the rear axle as
long as you have your hands on the bars.

While breaking, I think it's impossible to lean far enough back where you
would not put enough weight on the front wheel (which should do the majority
of the breaking). So, when you're leaning as far back as you can under the
hardest breaking you're putting your physical weight onto the rear wheel so
you can break with that better than normally, plus because of the
deaccelleration a LOT of weight is still on the front wheel so you can get
as much out of it as well.

You meant "braking", didn't you? (Yes, I know that breaking can be
related to braking, as in, failure of.)
Assuming you have the traction, at the point of greatest deceleration
all of the weight is on the front wheel. The smaller the angle between
the line from the center of mass to the front contact patch and the
road, the greater the possible deceleration.

Mike
http://mikebeauchamp.com

--
Ted Bennett
Portland OR

The amplitude and timing of the rider's movement within the system are
extremely important factors in hard braking, but these never seem to be
accounted for in anybody's theorems. The rider is always assumed to be still as
a statue during the act. I think there is another order of complexity that is
being missed.

Robert

That can be circumvented. Build a bike that positions your center of
gravity below the front axle. You could lock the wheel up tight and
still not do an endo.

No. The important dimension is where the center of mass is in relation
to the front wheel's contact patch. An endo is possible with the weight
below the axle, although not likely because of insufficient traction.
short version
a locked front wheel does not undo you, you skid and fall of sideways.

That can be circumvented. Build a bike that positions your center of
gravity below the front axle. You could lock the wheel up tight and
still not do an endo.

Almost anybody can lock up the front wheel tight by leaning back far enough
(meaning butt just over the rear wheel). You don't need to build any kind
of special bike... I do it on my MTB.

--
Phil, Squid-in-Training

wle wrote:
if you could position your center of gravity anywhere, to ensure
maximum braking power, where would it be?

As far back as possible, and brace hard against the bars.

~PB

On Thu, 08 Jan 2004 01:47:26 +0000, Ken wrote:

(wle) wrote in
. com:
there is a point, leaning either ahead of the front wheel, or
behind the back wheel, that the opposite wheel is off the ground.

Unless you're climbing a steep hill, you're going to have a real hard time
lifting the front wheel. If the hill is that steep, stopping shouldn't be a
problem.

Underground. ;-)

wle wrote:
if you could position your center of gravity anywhere, to ensure
maximum braking power, where would it be?

Evidently maximum braking power is a function of the angle described
between the ground and a line drawn through the contact patch and the CoG.
Hence for a given angle the CoG may move freely along that line without
influencing the braking power. Therefore to maximise braking power I would
position the CoG at the bottom bracket, assuming we are constrained to
having it within the bike-rider structure; otherwise, at ground level
below the BB or thereabouts (to have an even load on each wheel when not
braking or accellerating).

assume a level road, brakes that can cause a skid no matter what.

It is extremely unlikely that front brake will cause a skid no matter
what. If tyre traction is that poor then that is evidently the limiting
factor on braking, and the CoG may roam freely.
--
David Damerell Distortion Field!

ZeeExSixAre wrote:
Almost anybody can lock up the front wheel tight by leaning back far
enough (meaning butt just over the rear wheel). You don't need to
build any kind of special bike... I do it on my MTB.

You won't be able to get butt far back enough and still reach the bars on
a road bike to skid the front wheel (on clean dry road).

~PB

In article ,
Sheldon Brown wrote:

snip

See also http://sheldonbrown.com/brakturn.html

Sheldon "Geometry And Physics" Brown
+------------------------------------------+
| So we'll go no more a roving |
| So late into the night, |
| Though the heart be still as loving, |
| And the moon be still as bright. |
| |
| For the sword outwears its sheath, |
| And the soul wears out the breast, |
| And the heart must pause to breathe, |
| And Love itself have rest. |
| |
| Though the night was made for loving, |
| And the day returns too soon, |
| Yet we'll go no more a roving |
| By the light of the moon. |
| --Lord Byron |
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Phone 617-244-9772 FAX 617-244-1041
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Thanks for the Lord Byron - made my day.

The last time I locked my front wheel, I ended up hugging a pine tree.

HAND
Stay warm

--
"Freedom Is a Light for Which Many Have Died in Darkness"

- Tomb of the unknown - American Revolution

Cockpit of a 747?

Bill "landing, that is" S.