Braking while turning?

[Smokey]

Sir Ridesalot wrote:
> Here is the scenario. You are riding along at a good speed, you enter a
> turn and have leaned the bicycle when a car or pedestrian enters the
> road in front of you.
>
> You are not able to go around the obstruction.
>
> Is there a safe way to brake in such circumstances without having the
> bicycle slide out from under you?
>
> There is a long winding hill where I often ride here in town. Many
> times on the curve I have had either a car pull out in front of me or a
> person start to cross the road. Thus far I have been able to take
> evasive action by turning onto the side street the car was exiting
> from. I watch that intersection as soon as it comes in view.
>
> However I am curious as to whether there is a safe way to bleed off a
> lot of speed, ie brake, while still leaning in the curve if there was
> no time to make that panic turn.
>
> Thanks for all relevant advice.
>
> Peter

I used to teach motorcycle rider education as a Motorcycle Safety
Foundation certified instructor. We always taught our students that
traction was like a bank account. You only have a certain amount
available and when you exceed that, you skid and can fall, especially
if it involves the front wheel. Leaning into a curve takes a certain
amount, so you have to subtract that from the amount available for
braking. Wet road conditions also subtract from traction, particularly
when it first starts raining.

You can use both brakes in a turn, you just have to remember the basic
"traction account" principle. In our range exercises we taught two
methods. In the first, the rider remained leaned over and used the
brakes moderately, not exceeding the available traction. In the other
exercise, we taught them to quickly stand the bike up, brake hard, and
stop before crossing the line into the other lane.

Of course we also taught them to slow down for blind corners and turns
with other possible dangerous situations, like intersections. Proper
cornering lines and apexes were another principle we taught. In your
particular situation, I think I would first advise you to slow before
the turn. The other thing you might do is go to an empty parking lot
and practice the two exercises I mentioned. Finally, always keep your
head and eyes up and look through the turn. This is probably the most
important method of all.

Smokey

 

[[email protected]]

Peter who? writes:

> Here is the scenario. You are riding along at a good speed, you
> enter a turn and have leaned the bicycle when a car or pedestrian
> enters the road in front of you.

> You are not able to go around the obstruction.

> Is there a safe way to brake in such circumstances without having
> the bicycle slide out from under you?

> There is a long winding hill where I often ride here in town. Many
> times on the curve I have had either a car pull out in front of me
> or a person start to cross the road. Thus far I have been able to
> take evasive action by turning onto the side street the car was
> exiting from. I watch that intersection as soon as it comes in view.

> However I am curious as to whether there is a safe way to bleed off
> a lot of speed, ie brake, while still leaning in the curve if there
> was no time to make that panic turn.

This is mentioned in the FAQ:

http://www.sheldonbrown.com/brandt/descending.html

The essential part of that item is:

# Braking at maximum lean

# For braking in a curve, take the example of a rider cornering with
# good traction, leaning at 45 degrees, the equivalent of 1G
# centrifugal acceleration. Braking with 1/10g increases the traction
# demand by one half percent. The sum of cornering and braking
# vectors is the square root of the sum of their squares,
# SQRT(1^2+0.1^2)=1.005 or an increase of 0.005. In other words,
# there is room to brake substantially during maximum cornering.
# Because the lean angle changes as the square of the speed, braking
# can rapidly reduce the angle and allow even more braking. For this
# reason skilled racers nearly always apply both brakes into the apex
# of turns.

You can see an example of this if you back up from the above URL:

http://www.sheldonbrown.com/brandt/

Jobst Brandt

 

[Ryan Cousineau]

In article <[email protected]>,
[email protected] (Chris Z The Wheelman) wrote:

> Ride the hill slower if it's that dangerous, or better yet, find a safer
> hill! Hard braking in a hard turn usually equals a skid, so if it comes
> to that, purposly skid the rear wheel ala' BMX style. At least that way
> you'll be less likely to seriouly crash.

Chris, I've actually managed to drift a rear wheel in an ashphalt corner
and live (under race conditions, no less! I won the prime that was about
200m down the road) but I don't recommend it as a high-percentage move.

Jobst is pretty much completely in the right about the proper cornering
technique, which differs from that of motorcycles for a few reasons, not
least of which is that the Motorcycle Safety Foundation is designed to
lead you into high-percentage decisions like separating braking and
cornering.

Motorcycle racers, who are very good at things like handling a
motorcycle and who are willing to take the associated risks, happily
brake both wheels well past the corner entry point these days. Of
course, the dynamics of a motorcycle are so different from conventional
bicycles as to make comparisons...imperfect.

That said, the universal advice to not get in over your head is good
advice. The real trick to learning how to corner well is to approach the
limits of traction without ever exceeding them.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

 

[[email protected]]

Ryan Cousineau writes:

>> Ride the hill slower if it's that dangerous, or better yet, find a
>> safer hill! Hard braking in a hard turn usually equals a skid, so
>> if it comes to that, purposely skid the rear wheel ala' BMX style.
>> At least that way you'll be less likely to seriously crash.

> Chris, I've actually managed to drift a rear wheel in an asphalt
> corner and live (under race conditions, no less! I won the prime
> that was about 200m down the road) but I don't recommend it as a
> high-percentage move.

> Jobst is pretty much completely in the right about the proper
> cornering technique, which differs from that of motorcycles for a
> few reasons, not least of which is that the Motorcycle Safety
> Foundation is designed to lead you into high-percentage decisions
> like separating braking and cornering.

> Motorcycle racers, who are very good at things like handling a
> motorcycle and who are willing to take the associated risks, happily
> brake both wheels well past the corner entry point these days. Of
> course, the dynamics of a motorcycle are so different from
> conventional bicycles as to make comparisons... imperfect.

> That said, the universal advice to not get in over your head is good
> advice. The real trick to learning how to corner well is to
> approach the limits of traction without ever exceeding them.

That is asking a lot. How do you develop a feel for the limit? I and
my fellow fast descenders did it in younger days where falling seldom
caused more than pavement rash, without breaking bones. One of the
reasons I can assess accident reconstructions is that I have fallen
off a bicycle most any way possible... or was close by when someone
else did it.

The claims riders make for some of the cases brought to court are
highly credible to people who haven't done it. All the ones I have
seen were liars.

Jobst Brandt

 

[Ryan Cousineau]

In article <[email protected]>,
[email protected] wrote:

> Ryan Cousineau writes:
>
> >> Ride the hill slower if it's that dangerous, or better yet, find a
> >> safer hill! Hard braking in a hard turn usually equals a skid, so
> >> if it comes to that, purposely skid the rear wheel ala' BMX style.
> >> At least that way you'll be less likely to seriously crash.
>
> > Chris, I've actually managed to drift a rear wheel in an asphalt
> > corner and live (under race conditions, no less! I won the prime
> > that was about 200m down the road) but I don't recommend it as a
> > high-percentage move.
>
> > Jobst is pretty much completely in the right about the proper
> > cornering technique, which differs from that of motorcycles for a
> > few reasons, not least of which is that the Motorcycle Safety
> > Foundation is designed to lead you into high-percentage decisions
> > like separating braking and cornering.
>
> > Motorcycle racers, who are very good at things like handling a
> > motorcycle and who are willing to take the associated risks, happily
> > brake both wheels well past the corner entry point these days. Of
> > course, the dynamics of a motorcycle are so different from
> > conventional bicycles as to make comparisons... imperfect.
>
> > That said, the universal advice to not get in over your head is good
> > advice. The real trick to learning how to corner well is to
> > approach the limits of traction without ever exceeding them.
>
> That is asking a lot. How do you develop a feel for the limit? I and
> my fellow fast descenders did it in younger days where falling seldom
> caused more than pavement rash, without breaking bones. One of the
> reasons I can assess accident reconstructions is that I have fallen
> off a bicycle most any way possible... or was close by when someone
> else did it.

Indeed it is. My guess is that the best training is much like what has
worked very well for motorcycle racers: if you start on low-traction
surfaces (dirt), you're likely to learn a lot of skills that transfer
well to ashphalt.

I recently tested this theory out by riding my slick-tired road bike
through a bunch of unchallenging dirt-and-gravel trails. The road rash
was non-fatal.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

 

[Leo Lichtman]

Cars and motorcycles generally brake on the way into a corner, and
accelerate out. If you try to apply this sequence to a bicycle, it is
important not to ignore one important difference, and I don't remember
seeing it mentioned. Engine-powered vehicles can transfer weight to the
rear wheel by accelerating, thus inducing understeer. This stabilizes the
vehicle, and restores the formner speed. A cyclist can hardly expect to
induce understeer in this way. He is faced with the need to regain his
former momentum the old fashioned way. In order to conserve his momentum,
he is likely to brake less on the way in than a motorcyclist would. This
puts him at the apex with less uncommited traction, so there is a greater
likelihood of losing it. "Slow in and fast out," which is the rule for
motor vehicles, is not so good for bicycles.

 

[Bill Baka]

Leo Lichtman wrote:
> Cars and motorcycles generally brake on the way into a corner, and
> accelerate out. If you try to apply this sequence to a bicycle, it is
> important not to ignore one important difference, and I don't remember
> seeing it mentioned. Engine-powered vehicles can transfer weight to the
> rear wheel by accelerating, thus inducing understeer. This stabilizes the
> vehicle, and restores the formner speed. A cyclist can hardly expect to
> induce understeer in this way. He is faced with the need to regain his
> former momentum the old fashioned way. In order to conserve his momentum,
> he is likely to brake less on the way in than a motorcyclist would. This
> puts him at the apex with less uncommited traction, so there is a greater
> likelihood of losing it. "Slow in and fast out," which is the rule for
> motor vehicles, is not so good for bicycles.
>
>
As an aside, you also can not pedal if you are leaned over too far in a
tight corner or you will dump/crash when the lower pedal hits the
ground. I learned this the hard way like most 8 year olds trying to race
some other kids. Also with both motorcycles and Indy cars the racers
know to brake down to cornering speed before actually turning since in
the turn the tires are fully committed to lateral G forces. With a motor
vehicle and enough power you can achieve a rear wheel drift but this is
more for show than go. It only works with a front engine, rear wheel
drive car though, or a motorcycle, in which case you had better be
damned good before trying it on pavement.
Bill Baka

 

[[email protected]]

Leo Lichtman writes:

> Cars and motorcycles generally brake on the way into a corner, and
> accelerate out. If you try to apply this sequence to a bicycle, it
> is important not to ignore one important difference, and I don't
> remember seeing it mentioned. Engine-powered vehicles can transfer
> weight to the rear wheel by accelerating, thus inducing understeer.
> This stabilizes the vehicle, and restores the former speed. A
> cyclist can hardly expect to induce understeer in this way. He is
> faced with the need to regain his former momentum the old fashioned
> way. In order to conserve his momentum, he is likely to brake less
> on the way in than a motorcyclist would. This puts him at the apex
> with less uncommitted traction, so there is a greater likelihood of
> losing it. "Slow in and fast out," which is the rule for motor
> vehicles, is not so good for bicycles.

I think you'll find that point addressed in the FAQ I referenced:

http://www.sheldonbrown.com/brandt/descending.html

Along with an example of same, pictorially.

Jobst Brandt

 

[Terry Morse]

[email protected] wrote:

> http://www.sheldonbrown.com/brandt/descending.html

"Riders often prefer to keep their head upright in curves, although
leaning the head with the bicycle and body is more natural to the
motion. Pilots who roll their aircraft do not attempt to keep their
head level during the maneuver, or in curves, for that matter."

I've read this many times before, and I have tried leaning my head
with the bicycle over the years. I have the following problem doing
this: in order to maintain a good view of the pavement with this
techniqe, I have to crane my neck up and direct my gaze upwards.
Besides making my neck hurt, the necessary upward gaze is obscured
by the top of my eye glasses.
--
terry morse - Undiscovered Country Tours - http://udctours.com/

 

[Bill Baka]

Terry Morse wrote:
> [email protected] wrote:
>
>> http://www.sheldonbrown.com/brandt/descending.html
>
> "Riders often prefer to keep their head upright in curves, although
> leaning the head with the bicycle and body is more natural to the
> motion. Pilots who roll their aircraft do not attempt to keep their
> head level during the maneuver, or in curves, for that matter."

How could they if they do a 360?
>
> I've read this many times before, and I have tried leaning my head
> with the bicycle over the years. I have the following problem doing
> this: in order to maintain a good view of the pavement with this
> techniqe, I have to crane my neck up and direct my gaze upwards.
> Besides making my neck hurt, the necessary upward gaze is obscured
> by the top of my eye glasses.

NASCAR drivers complained about that at one of the paved ovals that bad
super banks of the turns so they could go faster. The problem was that
due to the extreme banks they could not see an accident in front of
them, something that is kind of important at 180 MPH. Anything more than
a few hundred feet was out of sight upwards in that high a bank.
Most normal roads are not banked and some are even banked the wrong way
due to some brilliant highway engineer who wanted the rain to drain to
the ditch on the outside of the turn. He must have forgot that cars
would be driving on that rain slicked road and the reverse banking would
make for more accidents. Ditto for bikes.
Bill Baka

 

[Tom Kunich]

"Terry Morse" <[email protected]> wrote in message
news:[email protected]...
> [email protected] wrote:
>
>> http://www.sheldonbrown.com/brandt/descending.html
>
> "Riders often prefer to keep their head upright in curves, although
> leaning the head with the bicycle and body is more natural to the
> motion. Pilots who roll their aircraft do not attempt to keep their
> head level during the maneuver, or in curves, for that matter."
>
> I've read this many times before, and I have tried leaning my head
> with the bicycle over the years. I have the following problem doing
> this: in order to maintain a good view of the pavement with this
> techniqe, I have to crane my neck up and direct my gaze upwards.
> Besides making my neck hurt, the necessary upward gaze is obscured
> by the top of my eye glasses.

Not to mention those bushy eyebrows of yours.

 

[[email protected]]

Terry Morse writes:

http://www.sheldonbrown.com/brandt/descending.html

# "Riders often prefer to keep their head upright in curves, although
# leaning the head with the bicycle and body is more natural to the
# motion. Pilots who roll their aircraft do not attempt to keep their
# head level during the maneuver, or in curves, for that matter."

> I've read this many times before, and I have tried leaning my head
> with the bicycle over the years. I have the following problem doing
> this: in order to maintain a good view of the pavement with this
> technique, I have to crane my neck up and direct my gaze upward.
> Besides making my neck hurt, the necessary upward gaze is obscured
> by the top of my eye glasses.

I think if you try it you'll find that if your hands are in the hooks
while braking, you have no alternative but to crane your neck back
regardless of how you tilt your head. Tilt and rotate is equivalent
to staying in line with the body. If your glasses are a problem then
they probably have too small an aperture in line with current fashion
of granny reading glasses.

Sitting here in front of my KBD I have little trouble tuning my face
upward to look at the ceiling (with reading glasses). That is more
tilt than I need to corner fast. Hairpin turns are another matter,
because they are not high speed cornering but more a parking maneuver.

Jobst Brandt

 

[Bill Baka]

[email protected] wrote:
> Terry Morse writes:
>
> http://www.sheldonbrown.com/brandt/descending.html
>
> # "Riders often prefer to keep their head upright in curves, although
> # leaning the head with the bicycle and body is more natural to the
> # motion. Pilots who roll their aircraft do not attempt to keep their
> # head level during the maneuver, or in curves, for that matter."
>
>> I've read this many times before, and I have tried leaning my head
>> with the bicycle over the years. I have the following problem doing
>> this: in order to maintain a good view of the pavement with this
>> technique, I have to crane my neck up and direct my gaze upward.
>> Besides making my neck hurt, the necessary upward gaze is obscured
>> by the top of my eye glasses.
>
> I think if you try it you'll find that if your hands are in the hooks
> while braking, you have no alternative but to crane your neck back
> regardless of how you tilt your head. Tilt and rotate is equivalent
> to staying in line with the body. If your glasses are a problem then
> they probably have too small an aperture in line with current fashion
> of granny reading glasses.
>
> Sitting here in front of my KBD I have little trouble tuning my face
> upward to look at the ceiling (with reading glasses). That is more
> tilt than I need to corner fast. Hairpin turns are another matter,
> because they are not high speed cornering but more a parking maneuver.
>
> Jobst Brandt

Agreed unless you are in an aero tuck and then you would really be
straining your neck. I sit up just enough to see even if it does cost a
few MPH, but then I am not racing anyone either. In the last 4 or 5
years of watching most of the Tour de France I have seen some pileups on
turns, and Lance's classic cut across the field. How does it work with a
recumbent?
Bill Baka

 

[Bill Bushnell]

Bill Baka <[email protected]> wrote:
> [email protected] wrote:
> > Sitting here in front of my KBD I have little trouble tuning my face
> > upward to look at the ceiling (with reading glasses). That is more
> > tilt than I need to corner fast. Hairpin turns are another matter,
> > because they are not high speed cornering but more a parking maneuver.

> Agreed unless you are in an aero tuck and then you would really be
> straining your neck. I sit up just enough to see even if it does cost a
> few MPH, but then I am not racing anyone either. In the last 4 or 5
> years of watching most of the Tour de France I have seen some pileups on
> turns, and Lance's classic cut across the field. How does it work with a
> recumbent?

Visibility through the corner is easier requiring less craning of the neck and
rolling of the eyes because the head is held at a natural attitude with respect
to the body, similar to that of an auto driver or airplane pilot. Because the
arms and wrists are relaxed, not having to support the weight of the upper body,
slight adjustments to the line through a corner can be made more easily without
overcompensating. Likewise with braking.

As for cutting across a field, it's been done a recumbent.

--
Bill Bushnell
http://pobox.com/~bushnell/

 

[Tom Kunich]

<[email protected]> wrote in message
news:[email protected]...
>
> Sitting here in front of my KBD I have little trouble tuning my face
> upward to look at the ceiling (with reading glasses). That is more
> tilt than I need to corner fast. Hairpin turns are another matter,
> because they are not high speed cornering but more a parking maneuver.

Jobst, are you forgetting that it is pretty difficult to get a bike with the
handlebars anywhere near high enough these days of small size bikes and
threadless forks?

When your handlebars were 1" below your seat a person could ride the drops
and tilt his head back far enough to look ahead even on steep hills. When
the fashion and components started forcing you to have a handlebar 3"-4"
below the seat a lot of people cannot tilt their heads back enough from the
drops (another 3" drop) to see far enough forward.

 

[[email protected]]

Tom Kunich writes:

>> Sitting here in front of my KBD I have little trouble tuning my
>> face upward to look at the ceiling (with reading glasses). That is
>> more tilt than I need to corner fast. Hairpin turns are another
>> matter, because they are not high speed cornering but more a
>> parking maneuver.

> Jobst, are you forgetting that it is pretty difficult to get a bike
> with the handlebars anywhere near high enough these days of small
> size bikes and threadless forks?

> When your handlebars were 1" below your seat a person could ride the
> drops and tilt his head back far enough to look ahead even on steep
> hills. When the fashion and components started forcing you to have a
> handlebar 3"-4" below the seat a lot of people cannot tilt their
> heads back enough from the drops (another 3" drop) to see far enough
> forward.

I have no difficulty doing that even when tucked in, chin on thumb at
stem level, which I do on all top speed descents where braking is not
required. That's a lot lower than hands in the hooks, braking.

Excuses, excuses, ex... You might think these guys are old and stiff
the way they sound.

Jobst Brandt

 

[Bill Baka]

[email protected] wrote:
> Tom Kunich writes:
>
>>> Sitting here in front of my KBD I have little trouble tuning my
>>> face upward to look at the ceiling (with reading glasses). That is
>>> more tilt than I need to corner fast. Hairpin turns are another
>>> matter, because they are not high speed cornering but more a
>>> parking maneuver.
>
>> Jobst, are you forgetting that it is pretty difficult to get a bike
>> with the handlebars anywhere near high enough these days of small
>> size bikes and threadless forks?
>
>> When your handlebars were 1" below your seat a person could ride the
>> drops and tilt his head back far enough to look ahead even on steep
>> hills. When the fashion and components started forcing you to have a
>> handlebar 3"-4" below the seat a lot of people cannot tilt their
>> heads back enough from the drops (another 3" drop) to see far enough
>> forward.
>
> I have no difficulty doing that even when tucked in, chin on thumb at
> stem level, which I do on all top speed descents where braking is not
> required. That's a lot lower than hands in the hooks, braking.
>
> Excuses, excuses, ex... You might think these guys are old and stiff
> the way they sound.
>
> Jobst Brandt

Some of us are old but not stiff. In my case I am very nearsighted and
if I have to look up from a total tuck every thing goes blurry looking
over the top of my glasses. Not that I slow down that much, but I do
have to sit up just a little to actually see in focus. I like going
downhill at 60 MPH or more if I can, but I also like to see what I might
hit, since I can't see even a 1" rock past 25 feet without my glasses
and that definitely could crash me. I have had 65 MPH motorcycle road
rash and I don't want a repeat on a mere bicycle. That would be too
embarrassing, even for me.
Bill Baka

 

[Bill Sornson]

Bill Baka wrote:

> ... I like going downhill at 60 MPH or more if I can

On what bike do you do this -- with no cyclometer, IIRC?

Sorry, Bill, gotta call BS...again.

BS, BS

 

[R Brickston]

On Wed, 30 Aug 2006 02:21:48 GMT, Bill Baka <[email protected]> wrote:

>[email protected] wrote:
>> Tom Kunich writes:
>>
>>>> Sitting here in front of my KBD I have little trouble tuning my
>>>> face upward to look at the ceiling (with reading glasses). That is
>>>> more tilt than I need to corner fast. Hairpin turns are another
>>>> matter, because they are not high speed cornering but more a
>>>> parking maneuver.
>>
>>> Jobst, are you forgetting that it is pretty difficult to get a bike
>>> with the handlebars anywhere near high enough these days of small
>>> size bikes and threadless forks?
>>
>>> When your handlebars were 1" below your seat a person could ride the
>>> drops and tilt his head back far enough to look ahead even on steep
>>> hills. When the fashion and components started forcing you to have a
>>> handlebar 3"-4" below the seat a lot of people cannot tilt their
>>> heads back enough from the drops (another 3" drop) to see far enough
>>> forward.
>>
>> I have no difficulty doing that even when tucked in, chin on thumb at
>> stem level, which I do on all top speed descents where braking is not
>> required. That's a lot lower than hands in the hooks, braking.
>>
>> Excuses, excuses, ex... You might think these guys are old and stiff
>> the way they sound.
>>
>> Jobst Brandt
>
>Some of us are old but not stiff. In my case I am very nearsighted and
>if I have to look up from a total tuck every thing goes blurry looking
>over the top of my glasses. Not that I slow down that much, but I do
>have to sit up just a little to actually see in focus. I like going
>downhill at 60 MPH or more if I can, but I also like to see what I might
>hit, since I can't see even a 1" rock past 25 feet without my glasses
>and that definitely could crash me. I have had 65 MPH motorcycle road
>rash and I don't want a repeat on a mere bicycle. That would be too
>embarrassing, even for me.
>Bill Baka


"I like going downhill at 60 MPH or more if I can..."

Off a cliff.

 

[R Brickston]

On Wed, 30 Aug 2006 05:12:44 GMT, "Bill Sornson" <[email protected]> wrote:

>Bill Baka wrote:
>
>> ... I like going downhill at 60 MPH or more if I can
>
>On what bike do you do this -- with no cyclometer, IIRC?
>
>Sorry, Bill, gotta call BS...again.
>
>BS, BS
>

Oh, Billy is quite unstoppable. Next he'll tell you about putting the
car on the same hill and coasting to give afairly accurate speed
reading on the bike.