Engine breaking instead of handle/pedal

In article <5hf1btF3kk5d6U1.RemoveThis@mid.individual.net>,
"Konrad Viltersten" <tmp1.RemoveThis@viltersten.com> wrote:

> I'm not entirely sure what it's called in english but i
> understand that one's supposed to break without the
> actuall brakes being hit. It's due to the fact that
> energy gets consumed to make the engine spin, i got
> to know.

I suppose that superstitions about not using a motorcycle's brakes still
survive from when they were made of leather and could eventually slow
you down if you were going uphill. Modern motorcycle brakes are made of
advanced materials and designs that can stand up to hard braking.

You *should* use your brakes to slow down. At least 2/3 of your braking
power is in the front wheel, and you won't tip the bike up and over
unless you're riding a sport bike and you brake really, really hard. You
should practice hard braking. That way, when you need to do it in
traffic, you'll already know how.

> So, i went for a drive today but i don't seem to be
> able to get it to work. The only thing i managed to
> accomplish was to accelerate (turning the gas more
> "on") and then decelerate (by the very opposite
> action).
>
> By other words - if i add gas i speed up, if i lower
> gas i slow down. Great, but where is the engine
> breaking i'm supposed to take advantage of?!

When you close the throttle and the bike slows down, that's engine
braking. Others explained it in greater detail.

> Also, i wonder what can happen if i release the
> clutch entirely and let the gas slowly to be turned
> off. Will the engine die? Will i stop rapidly?

The engine should not die. It should drop to its idle speed. With the
clutch squeezed, there's no connection between the engine and the rear
wheel; the bike should continue to roll freely.

> What happens if the clutch is entirely released and
> the gas handle gets released fast instead?

Engine braking.

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
It's easy to say a war is so important your neighbor should go fight it for you.
 >> Stay informed about: Engine breaking instead of handle/pedal 

In article <761ce9a00baab@uwe>,
"Albrecht via MotorcycleKB.com" <u33665@uwe> wrote:

> Konrad Viltersten wrote:
> >I'm not entirely sure what it's called in english but i understand
> >that one's supposed to break without the actuall brakes being hit.
> >It's due to the fact that energy gets consumed to make the engine
> >spin, i got to know.
>
> It's called "engine braking". Your engine acts as an air pump,
> expending about 1/3rd of all the energy available from the fuel in
> pumping fresh air in and expended gasses out of the engine.

I don't believe that. 33% energy loss to pumping strikes me as
unreasonably high. Can you find me a reference for that number?

> Engineers call this wasted energy "pumping loss". Engineers also
> include the air under the piston that gets compressed on the down
> stroke as "pumping loss". They provide passageways between cylinder
> pairs so the air has somewhere to go insterad of being compressed.

There's also the PCV valve which directs crankcase gases into the intake
manifold.

(How does a single-cylinder engine, or an inline twin with 0° piston
offset manage the air?)

<snip>

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
It's easy to say a war is so important your neighbor should go fight it for you.
 >> Stay informed about: Engine breaking instead of handle/pedal 

Timberwoof wrote:

>I suppose that superstitions about not using a motorcycle's brakes still
>survive from when they were made of leather and could eventually slow
>you down if you were going uphill. Modern motorcycle brakes are made of
>advanced materials and designs that can stand up to hard braking.

Well, there is some truth in that old story. Some riders probably
actually flipped over the handlebars in the 1940's or 1950's after they
installed really soft braking linings with high friction coefficient.

Drum brakes have a self-energizing effect and just applying the brakes
lightly makes the brakes energize themselves. Soft lining would
self-energize to the point of lock up and would not disengage.

The critical mu was about 0.4. Once applied, the front brakes would lock due
to the self energizing effect of the drum pulling the brake shoe towards
itself.

"Mu" is the Greek letter representing the ratio of braking force to
normal force applied by the caliper piston.

mu = F/n

Typical values for disk brake pad Mu are about 0.3, IOW, you get less than
1/3rd of a pound of braking force for every pound of pressure applied to the
brake pad.

Motorcycles often come with rather high mu (soft) brake pads and new
owners notice a lot of front end dive for very little braking effort.

Aftermarket pads are usually lower mu (hard) pads, and, while they take
more effort, the rider feels like he's in control.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/bike/200708/1
 >> Stay informed about: Engine breaking instead of handle/pedal 

In article <761e0ceba0827@uwe>,
"Albrecht via MotorcycleKB.com" <u33665@uwe> wrote:

> Timberwoof wrote:
>
> >I suppose that superstitions about not using a motorcycle's brakes still
> >survive from when they were made of leather and could eventually slow
> >you down if you were going uphill. Modern motorcycle brakes are made of
> >advanced materials and designs that can stand up to hard braking.
>
> Well, there is some truth in that old story. Some riders probably
> actually flipped over the handlebars in the 1940's or 1950's after they
> installed really soft braking linings with high friction coefficient.
>
> Drum brakes have a self-energizing effect

.... if the shoe has its hinge at the trailing edge. Old VW brake hubs
had one shoe hinged at the leading edge and the other at the trailing
edge; only one would typically get stuck this way. Some cars had the
brake piston arranged so that both shows were self-energizing ... when
the car was moving forwards.

> and just applying the brakes
> lightly makes the brakes energize themselves. Soft lining would
> self-energize to the point of lock up and would not disengage.
>
> The critical mu was about 0.4. Once applied, the front brakes would lock due
> to the self energizing effect of the drum pulling the brake shoe towards
> itself.
>
> "Mu" is the Greek letter representing the ratio of braking force to
> normal force applied by the caliper piston.
>
> mu = F/n

.... where F is the maximum friction force and n is the force applied at
right angles to the surface.

> Typical values for disk brake pad Mu are about 0.3, IOW, you get less than
> 1/3rd of a pound of braking force for every pound of pressure applied to the
> brake pad.

This is all balanced out by the resistance of the material to wear and
further by the hydraulic advantage of the relatively narrow master
cylinders and the wide and multiple slave cylinders.

> Motorcycles often come with rather high mu (soft) brake pads and new
> owners notice a lot of front end dive for very little braking effort.

Mine has very little brake dive even if I have to brake relatively hard.


> Aftermarket pads are usually lower mu (hard) pads, and, while they take
> more effort, the rider feels like he's in control.

A brake pad that did not stop the bike as well for the same applied
force would make me feel less in control. It's the same feeling as when
the brakes are wet. I don't like it.

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
It's easy to say a war is so important your neighbor should go fight it for you.
 >> Stay informed about: Engine breaking instead of handle/pedal 

"Albrecht via MotorcycleKB.com" <u33665@uwe> wrote in message
news:761e0ceba0827@uwe...
> Timberwoof wrote:
>
>>I suppose that superstitions about not using a motorcycle's brakes still
>>survive from when they were made of leather and could eventually slow
>>you down if you were going uphill. Modern motorcycle brakes are made of
>>advanced materials and designs that can stand up to hard braking.
>
> Well, there is some truth in that old story. Some riders probably
> actually flipped over the handlebars in the 1940's or 1950's after they
> installed really soft braking linings with high friction coefficient.
>

I notice you qualify that with "probably" and I'm curious to know if there
are any proven accounts of that actually happening. When Honda went to
integrated braking on the 6 cylinder Wings in 1988, they linked one front
disc to the rear brake pedal - supposedly, the justification was that too
many new riders had been told that front only breaking could result in a
rear over front endo. Somehow, I can't imagine anyone, no matter how ham
fisted accomplishing this on a 900 lb. GW but I'm curious if there was ever
any real truth to the tale.

My BMW RT also links the front & rear - but the main control is the front
lever for normal braking (a computer apportions F-R braking amount). The
pedal by itself operates only the rear brake or it increases rear braking in
conjunction with the lever. Apparently, this has led to premature rear pad
wear among some riders who always use both lever and pedal, being used to
conventional non-linked systems. So normally, I use only the lever for
braking and both front and rear pads are only about 1/2 worn at 18,000
miles.

Tom K.
 >> Stay informed about: Engine breaking instead of handle/pedal 

"Albrecht via MotorcycleKB.com" <u33665@uwe> wrote in message
news:7627903169dc3@uwe...
> Tom K. wrote:
>
>>I notice you qualify that with "probably" and I'm curious to know if there
>>are any proven accounts of that actually happening.
>
> I wish that I could tell you that Winfield Q. Crankstroker locked up the
> front brake on his 1927 Broad Arrow W27 and thus a legend was born. But,
> who
> knows who the first rider was that went over the handlebars? How tall was
> he,
> what was the wheelbase and center of gravity height of his motorcycle?
> What was the mu of his brake shoes, what was the servo factor of the
> leading
> brake shoe?
>
> The legend of locked front brake shoes led Gordon Jennings to write an
> extensive article about drum brake self energization in Cycle World back
> in
> the
> early 1970's. Jennings was an engineer and he must have believed the story
> of riders being thrown over the handlebars, or he wouldn't have applied
> his
> engineering expertise.
>
> Too bad Gordo died. He left Motor Cyclist magazine without a tech writer
> worthy of the title.

Agreed. I didn't even know he was at Motor Cyclist., but I read Gordon
Jennings in every issue of CYCLE while he was there. He was a good writer
who communicated well with riders as well as being an absolute expert in the
field of motorcycling. The second last I heard of him, he was making a
living as motorcycle expert in court trials. Then I heard how he made an
ass of himself by arguing with a track official wanting him to move back
from the edge of a race track. That seemed an ignominious end to a proud
career. What happened in his last years?
 >> Stay informed about: Engine breaking instead of handle/pedal 

Tom K. wrote:

>I notice you qualify that with "probably" and I'm curious to know if there
>are any proven accounts of that actually happening.

I wish that I could tell you that Winfield Q. Crankstroker locked up the
front brake on his 1927 Broad Arrow W27 and thus a legend was born. But, who
knows who the first rider was that went over the handlebars? How tall was he,
what was the wheelbase and center of gravity height of his motorcycle?
What was the mu of his brake shoes, what was the servo factor of the leading
brake shoe?

The legend of locked front brake shoes led Gordon Jennings to write an
extensive article about drum brake self energization in Cycle World back in
the
early 1970's. Jennings was an engineer and he must have believed the story
of riders being thrown over the handlebars, or he wouldn't have applied his
engineering expertise.

Too bad Gordo died. He left Motor Cyclist magazine without a tech writer
worthy of the title.

I personally have been surprised by the rear wheel of a sportbike lifting off
the ground under what I felt was gentle application of the powerful front
brake with its grabby soft OEM brake pads. I bought some harder aftermarket
pads on the way home.

It only takes about a 1-g stop to transfer all a sportbike's weight to the
front wheel, any more force applied causes the motorcycle to complete an
"endo.

This assumes that the sportbike has street compound tires. It might stop at
about 1.3 g's with gumball tires.

Cruisers will slide the front tire instead, because of the lower center of
mass.

Stuntas trying to do incomplete "endos" probably know nothing about the
change from sliding friction to breakaway friction that occurs as they come
to a complete stop. Coefficient of friction suddenly triples, and so does
braking force
on the rotor. The front brake locks up, and the stunta goes over the bars.

>When Honda went to
>integrated braking on the 6 cylinder Wings in 1988, they linked one front
>disc to the rear brake pedal - supposedly, the justification was that too
>many new riders had been told that front only breaking could result in a
>rear over front endo.

Many newbie riders are hind foot brakers when they begin riding. Honda's
linked braking system makes them use the front brake whether they want to or
not.

The first time I ever locked up the rear wheel on a Honda with independant
front and rear braking systems, the rear wheel started coming around, and I
quickly reasoned that I needed to grab a big handful of front brake to
straighten the bike out. Needless to say, I was wrong and crashed.

As I pushed my broken Honda home, I passed the Hells Angels clubhouse and
they made fun of me for pushing a Japanese motorcycle...

--
Message posted via http://www.motorcyclekb.com
 >> Stay informed about: Engine breaking instead of handle/pedal 

Seth Hammond wrote:

What happened in his last years?

Gordon Jennings died on November 13 , 2000 , from cancer at the age of 69.
Jennings was editor of Cycle magazine in the 60s , held positions at Road &
Track , Car & Driver , and was a regular columnist in Motorcyclist.

--
Message posted via MotorcycleKB.com
http://www.motorcyclekb.com/Uwe/Forums.aspx/bike/200708/1
 >> Stay informed about: Engine breaking instead of handle/pedal 

Thanks!


"Albrecht via MotorcycleKB.com" <u33665@uwe> wrote in message
news:7627f5c2d5fe0@uwe...
> Seth Hammond wrote:
>
> What happened in his last years?
>
> Gordon Jennings died on November 13 , 2000 , from cancer at the age of 69.
> Jennings was editor of Cycle magazine in the 60s , held positions at Road
> &
> Track , Car & Driver , and was a regular columnist in Motorcyclist.
>
> --
> Message posted via MotorcycleKB.com
> http://www.motorcyclekb.com/Uwe/Forums.aspx/bike/200708/1
>
 >> Stay informed about: Engine breaking instead of handle/pedal 

"Konrad Viltersten" <tmp1.DeleteThis@viltersten.com> wrote in message
news:5hf1btF3kk5d6U1@mid.individual.net...
> I'm not entirely sure what it's called in english but i
> understand that one's supposed to break without the
> actuall brakes being hit. It's due to the fact that
> energy gets consumed to make the engine spin, i got
> to know.
>
> So, i went for a drive today but i don't seem to be
> able to get it to work. The only thing i managed to
> accomplish was to accelerate (turning the gas more
> "on") and then decelerate (by the very opposite
> action).
>
> By other words - if i add gas i speed up, if i lower
> gas i slow down. Great, but where is the engine
> breaking i'm supposed to take advantage of?!
>
> Also, i wonder what can happen if i release the
> clutch entirely and let the gas slowly to be turned
> off. Will the engine die? Will i stop rapidly?
>
> What happens if the clutch is entirely released and
> the gas handle gets released fast instead?

Down shifting/engine-braking is mainly used to make a loud aggressive noise
as you rapidly slow down to avoid a numpty car driver who's pulled out
leaving only just enough distance to stop/avoid them. This also leaves you
in low gear ready to take any needed evasive action - and make an impressive
roar as you do so.
 >> Stay informed about: Engine breaking instead of handle/pedal 

In article <y4nti.10310$vi3.3029@newsfe2-gui.ntli.net>,
"ian field" <dai.ode RemoveThis @ntlworld.com> wrote:

> Down shifting/engine-braking is mainly used to make a loud aggressive noise
> as you rapidly slow down to avoid a numpty car driver who's pulled out
> leaving only just enough distance to stop/avoid them. This also leaves you
> in low gear ready to take any needed evasive action - and make an impressive
> roar as you do so.

Brake braking is more effective.

--
Timberwoof <me at timberwoof dot com>
faq: http://www.timberwoof.com/motorcycle/faq.shtml
It's easy to say a war is so important your neighbor should go fight it for you.
 >> Stay informed about: Engine breaking instead of handle/pedal 

"Timberwoof" <timberwoof.spam.TakeThisOut@infernosoft.com> wrote in message
news:timberwoof.spam-C2EDF6.19514705082007@nnrp-virt.nntp.sonic.net...
> In article <y4nti.10310$vi3.3029@newsfe2-gui.ntli.net>,
> "ian field" <dai.ode.TakeThisOut@ntlworld.com> wrote:
>
>> Down shifting/engine-braking is mainly used to make a loud aggressive
>> noise
>> as you rapidly slow down to avoid a numpty car driver who's pulled out
>> leaving only just enough distance to stop/avoid them. This also leaves
>> you
>> in low gear ready to take any needed evasive action - and make an
>> impressive
>> roar as you do so.
>
> Brake braking is more effective.

That's perfectly true, but the advantage of loud aggressive downshifting is
that bystanders look and see the twat in the car pulling out on you.
 >> Stay informed about: Engine breaking instead of handle/pedal 

"Timberwoof" <timberwoof.spam.RemoveThis@infernosoft.com> wrote in message
news:timberwoof.spam-2536F5.10423406082007@nnrp-virt.nntp.sonic.net...
> In article <NWGti.2840$ka7.528@newsfe4-gui.ntli.net>,
> "ian field" <dai.ode.RemoveThis@ntlworld.com> wrote:
>
>> "Timberwoof" <timberwoof.spam.RemoveThis@infernosoft.com> wrote in message
>> news:timberwoof.spam-C2EDF6.19514705082007@nnrp-virt.nntp.sonic.net...
>> > In article <y4nti.10310$vi3.3029@newsfe2-gui.ntli.net>,
>> > "ian field" <dai.ode.RemoveThis@ntlworld.com> wrote:
>> >
>> >> Down shifting/engine-braking is mainly used to make a loud aggressive
>> >> noise
>> >> as you rapidly slow down to avoid a numpty car driver who's pulled out
>> >> leaving only just enough distance to stop/avoid them. This also leaves
>> >> you
>> >> in low gear ready to take any needed evasive action - and make an
>> >> impressive
>> >> roar as you do so.
>> >
>> > Brake braking is more effective.
>>
>> That's perfectly true, but the advantage of loud aggressive downshifting
>> is
>> that bystanders look and see the twat in the car pulling out on you.
>
> Hmmm. So if you had the choice of applying maximum brake-braking and
> avoiding injury and damage or doing loud, spectacular and ineffective
> engin-braking followed by a loud, spectacular, and painful impact, you'd
> choose the latter. Okay, just so we're clear.
>
> --
> Timberwoof <me at timberwoof dot com>

The gene pool is to a large extent self-cleansing.
 >> Stay informed about: Engine breaking instead of handle/pedal