Traction

Joerg

your youngster description seems more dirt tracking than counter steering.

opposite lock.

On 2/20/2016 5:03 PM, Joerg wrote:
On 2016-02-16 16:34, Frank Krygowski wrote:
We got 12" of wet, dense snow today, but the plows came out, and the
roads aren't terrible, despite a bit of slush and some snowy patches. So
this evening, when I had to pick up a prescription at the local
pharmacy, I flicked on the dynohub headlight & taillight and rode to the
pharmacy and back. As I did so, I noticed a reflex retained from my
teenage years of winter newspaper delivery by bicycle.

When I'm making a turn on a surface that is, or might be, very slippery,
of course I slow down. But I also reflexively make an effort to keep
the bike vertical. To balance, I lean my body inward from the bike.

Obviously, the center of gravity of my body+bike must be a bit inward
(i.e. toward the center of the curve) for balance and stability. The
amount the c.g. is inward is a simple function of speed and radius of
turn. But in dry conditions, I achieve this by tilting the bike while
keeping my body in the normal position relative to the bike. In
slippery conditions, I do it instead by leaning my body away from the
bike.

Do others do this? If so, why?

To achieve a certain lateral acceleration (or sharpness of turn), the
amount of lateral friction force (or traction) is fixed. And I don't
think there's any great difference in friction coefficient for my
Paselas when they're vertical vs. tilted, so the likelihood of a skid
shouldn't be much different. Psychologically, it _feels_ like some sort
of secondary effect - as if I have a better chance of stopping the
slide, or catching the bike, or just not falling, if the bike is
vertical.


Usually the bike is leaned and the body counteracts the lean a bit, like
he

https://www.youtube.com/watch?v=WkK05NXLFhk

That's really not a very comparable situation. Those guys are putting
their feet down toward the inside of the curve and using them as a
sliding support. They are not balancing as a bicyclist does.


At least that's how I learned it early on. Mostly because as a kid I
preferred riding my bicycle on motocross circuits, often in the rain
when nobody was out there. Fun! (well, my mom didn't think so when she
saw my clothes)


Maybe this is a valuable reflex I picked up by trial and error in my
paperboy days. Or maybe it's some unconscious superstition. At my age,
I'm a bit afraid to do an A-B test to see.

So: Comments?


Strange. I do it opposite and see others do it similarly: Lean the bike
and then move the upper body opposite, towards the outside of the curve.
This keeps the CG more towards the line where the wheels roll.

If a person is actually balancing a bike around a curve, the CG can be
only in one angular location relative to the line between the two tires
contact patches. This sketch shows that angle:
https://qph.is.quoracdn.net/main-qim...to_webp=t rue

Any body contortion - either my leaning my body more inward while
keeping the bike more vertical, or your opposite strategy - cannot
affect the orientation of the CG. It can't change the balance point.

That's why I said that my instinct for keeping the bike more vertical
must be due to some secondary effect, if it has any validity at all.

I think what's needed is for someone to try going too fast around
slippery corners over and over, testing all three strategies: rider in
the plane of the bike frame (i.e. normal), rider toward the center of
the plane of the frame (my reflex), and rider toward the outside (your
reflex). Test the strategies until it's clear which one gives the best
chance of recovering without a fall.

Obviously, it has to be someone willing to fall over and over. (Where's
Dan O when we need him?)

--
- Frank Krygowski

Dan O

Frank, your language specificity tails of from the generator discussion. Not critical but clearing...

Your suggested 'balance' motion is in the direction of counter steering...moving into the area of unturned front wheel with falling frame into corner direction.
You are moving toward what you're 'calling' balance that is a counter steering attitude coherent with a bicycle physics balance ... a low vehicle ground friction area.

"Frank Krygowski" wrote in message ...
On 2/20/2016 5:03 PM, Joerg wrote:
On 2016-02-16 16:34, Frank Krygowski wrote:
We got 12" of wet, dense snow today, but the plows came out, and the
roads aren't terrible, despite a bit of slush and some snowy patches. So
this evening, when I had to pick up a prescription at the local
pharmacy, I flicked on the dynohub headlight & taillight and rode to the
pharmacy and back. As I did so, I noticed a reflex retained from my
teenage years of winter newspaper delivery by bicycle.

When I'm making a turn on a surface that is, or might be, very slippery,
of course I slow down. But I also reflexively make an effort to keep
the bike vertical. To balance, I lean my body inward from the bike.

Obviously, the center of gravity of my body+bike must be a bit inward
(i.e. toward the center of the curve) for balance and stability. The
amount the c.g. is inward is a simple function of speed and radius of
turn. But in dry conditions, I achieve this by tilting the bike while
keeping my body in the normal position relative to the bike. In
slippery conditions, I do it instead by leaning my body away from the
bike.

Do others do this? If so, why?

To achieve a certain lateral acceleration (or sharpness of turn), the
amount of lateral friction force (or traction) is fixed. And I don't
think there's any great difference in friction coefficient for my
Paselas when they're vertical vs. tilted, so the likelihood of a skid
shouldn't be much different. Psychologically, it _feels_ like some sort
of secondary effect - as if I have a better chance of stopping the
slide, or catching the bike, or just not falling, if the bike is
vertical.


Usually the bike is leaned and the body counteracts the lean a bit, like
he

https://www.youtube.com/watch?v=WkK05NXLFhk

That's really not a very comparable situation. Those guys are putting
their feet down toward the inside of the curve and using them as a
sliding support. They are not balancing as a bicyclist does.


At least that's how I learned it early on. Mostly because as a kid I
preferred riding my bicycle on motocross circuits, often in the rain
when nobody was out there. Fun! (well, my mom didn't think so when she
saw my clothes)


Maybe this is a valuable reflex I picked up by trial and error in my
paperboy days. Or maybe it's some unconscious superstition. At my age,
I'm a bit afraid to do an A-B test to see.

So: Comments?


Strange. I do it opposite and see others do it similarly: Lean the bike
and then move the upper body opposite, towards the outside of the curve.
This keeps the CG more towards the line where the wheels roll.

If a person is actually balancing a bike around a curve, the CG can be
only in one angular location relative to the line between the two tires
contact patches. This sketch shows that angle:
https://qph.is.quoracdn.net/main-qim...to_webp=t rue

Any body contortion - either my leaning my body more inward while
keeping the bike more vertical, or your opposite strategy - cannot
affect the orientation of the CG. It can't change the balance point.

That's why I said that my instinct for keeping the bike more vertical
must be due to some secondary effect, if it has any validity at all.

OK here is just an idea for discussion. Could it be due to the fact that while the line from the contact patch to the C of G is in fact a straight line as shown in your diagram by doing what you describe you are effectively forming a partially closed hinge with the bike being one half and your body the other. If the tyres lose traction then that hinge will start to open as the bike starts to rotate below you towards the inside of the curve. The fact that this could happen before your C of G starts to accelerate downwards due to inertial effects (the bike is much lighter than you) might buy you fractions of a second sufficient for you to take action or for the tyres to have crossed the slippery patch and regained grip. Those actions might include raising your C of G or pulling up hard on the inside bar as the bike starts to rotate both of which might increase the contact pressure enough to regain traction. Here I think it needs a few sums to see if the geometry of my opening hinge anology makes either of these two effects credible.

Cheers,

Graham.

https://upload.wikimedia.org/wikiped...nquisition.jpg

On 2/21/2016 5:02 AM, Graham wrote:

"Frank Krygowski" wrote in message ...


Any body contortion - either my leaning my body more inward while
keeping the bike more vertical, or your opposite strategy - cannot
affect the orientation of the CG. It can't change the balance point.

That's why I said that my instinct for keeping the bike more vertical
must be due to some secondary effect, if it has any validity at all.

OK here is just an idea for discussion. Could it be due to the fact that while the line from the contact patch to the C of G is in fact a straight line as shown in your diagram by doing what you describe you are effectively forming a partially closed hinge with the bike being one half and your body the other. If the tyres lose traction then that hinge will start to open as the bike starts to rotate below you towards the inside of the curve. The fact that this could happen before your C of G starts to accelerate downwards due to inertial effects (the bike is much lighter than you) might buy you fractions of a second sufficient for you to take action or for the tyres to have crossed the slippery patch and regained grip. Those actions might include raising your C of G or pulling up hard on the inside bar as the bike starts to rotate both of which might increase the contact pressure enough to regain traction. Here I think it needs a few sums to see if the geometry of my opening hinge
anology makes either of these two effects credible.

That's the sort of thing I was wondering about. At this point, I don't
have any clear grasp of the specifics, though.


--
- Frank Krygowski

Frank Krygowski wrote:
:On 2/21/2016 5:02 AM, Graham wrote:
:
: "Frank Krygowski" wrote in message ...
:
:
: Any body contortion - either my leaning my body more inward while
: keeping the bike more vertical, or your opposite strategy - cannot
: affect the orientation of the CG. It can't change the balance point.
:
: That's why I said that my instinct for keeping the bike more vertical
: must be due to some secondary effect, if it has any validity at all.
:
: OK here is just an idea for discussion. Could it be due to the fact that while the line from the contact patch to the C of G is in fact a straight line as shown in your diagram by doing what you describe you are effectively forming a partially closed hinge with the bike being one half and your body the other. If the tyres lose traction then that hinge will start to open as the bike starts to rotate below you towards the inside of the curve. The fact that this could happen before your C of G starts to accelerate downwards due to inertial effects (the bike is much lighter than you) might buy you fractions of a second sufficient for you to take action or for the tyres to have crossed the slippery patch and regained grip. Those actions might include raising your C of G or pulling up hard on the inside bar as the bike starts to rotate both of which might increase the contact pressure enough to regain traction. Here I think it needs a few sums to see if the geometry of my opening hinge
:anology makes either of these two effects credible.

:That's the sort of thing I was wondering about. At this point, I don't
:have any clear grasp of the specifics, though.

My experience from riding in muck and snow and such, is that I
generally do what Frank described (keep the bike more upright).
I can lever the bike over to the outside if I need to, and if the bike
slides it's not going to run out of tire, which can happen when
leanning it.


--
sig 85

"Graham" writes:

OK here is just an idea for discussion. Could it be due to the fact
that while the line from the contact patch to the C of G is in fact a
straight line as shown in your diagram by doing what you describe you
are effectively forming a partially closed hinge with the bike being
one half and your body the other. If the tyres lose traction then that
hinge will start to open as the bike starts to rotate below you
towards the inside of the curve. The fact that this could happen
before your C of G starts to accelerate downwards due to inertial
effects (the bike is much lighter than you) might buy you fractions of
a second sufficient for you to take action or for the tyres to have
crossed the slippery patch and regained grip. Those actions might
include raising your C of G or pulling up hard on the inside bar as
the bike starts to rotate both of which might increase the contact
pressure enough to regain traction. Here I think it needs a few sums
to see if the geometry of my opening hinge anology makes either of
these two effects credible.

Consider the suspension aspect. A softer suspension will better deal
with small bumps, etc. With the rider on the seat, and in the plane of
the bike, the effective suspension is at its stiffest. Any deviation
from this (leaning in or out, standing on the pedals) is going to
improve this. I'm not saying this is significant, but it's something
to consider.

--
Joe Riel

On 2016-02-20 16:46, Frank Krygowski wrote:
On 2/20/2016 5:03 PM, Joerg wrote:
On 2016-02-16 16:34, Frank Krygowski wrote:
We got 12" of wet, dense snow today, but the plows came out, and the
roads aren't terrible, despite a bit of slush and some snowy patches. So
this evening, when I had to pick up a prescription at the local
pharmacy, I flicked on the dynohub headlight & taillight and rode to the
pharmacy and back. As I did so, I noticed a reflex retained from my
teenage years of winter newspaper delivery by bicycle.

When I'm making a turn on a surface that is, or might be, very slippery,
of course I slow down. But I also reflexively make an effort to keep
the bike vertical. To balance, I lean my body inward from the bike.

Obviously, the center of gravity of my body+bike must be a bit inward
(i.e. toward the center of the curve) for balance and stability. The
amount the c.g. is inward is a simple function of speed and radius of
turn. But in dry conditions, I achieve this by tilting the bike while
keeping my body in the normal position relative to the bike. In
slippery conditions, I do it instead by leaning my body away from the
bike.

Do others do this? If so, why?

To achieve a certain lateral acceleration (or sharpness of turn), the
amount of lateral friction force (or traction) is fixed. And I don't
think there's any great difference in friction coefficient for my
Paselas when they're vertical vs. tilted, so the likelihood of a skid
shouldn't be much different. Psychologically, it _feels_ like some sort
of secondary effect - as if I have a better chance of stopping the
slide, or catching the bike, or just not falling, if the bike is
vertical.


Usually the bike is leaned and the body counteracts the lean a bit, like
he

https://www.youtube.com/watch?v=WkK05NXLFhk

That's really not a very comparable situation. Those guys are putting
their feet down toward the inside of the curve and using them as a
sliding support. They are not balancing as a bicyclist does.


At least that's how I learned it early on. Mostly because as a kid I
preferred riding my bicycle on motocross circuits, often in the rain
when nobody was out there. Fun! (well, my mom didn't think so when she
saw my clothes)


Maybe this is a valuable reflex I picked up by trial and error in my
paperboy days. Or maybe it's some unconscious superstition. At my age,
I'm a bit afraid to do an A-B test to see.

So: Comments?


Strange. I do it opposite and see others do it similarly: Lean the bike
and then move the upper body opposite, towards the outside of the curve.
This keeps the CG more towards the line where the wheels roll.

If a person is actually balancing a bike around a curve, the CG can be
only in one angular location relative to the line between the two tires
contact patches. This sketch shows that angle:
https://qph.is.quoracdn.net/main-qim...to_webp=t rue


Any body contortion - either my leaning my body more inward while
keeping the bike more vertical, or your opposite strategy - cannot
affect the orientation of the CG. It can't change the balance point.


True, but ... when you lean your body into the curve and the thing
surprisingly starts to skid setting a foot out can cause a nasty fall or
a broken ankle. Or worse, hip damage. Leaning like the dirt bikers has
you already almost vertical, much less chance for hip damage.

Also, often I already have the foot out inches above the surface, just
in case.


That's why I said that my instinct for keeping the bike more vertical
must be due to some secondary effect, if it has any validity at all.

I think what's needed is for someone to try going too fast around
slippery corners over and over, testing all three strategies: rider in
the plane of the bike frame (i.e. normal), rider toward the center of
the plane of the frame (my reflex), and rider toward the outside (your
reflex). Test the strategies until it's clear which one gives the best
chance of recovering without a fall.

Obviously, it has to be someone willing to fall over and over. (Where's
Dan O when we need him?)


:-)

--
Regards, Joerg

http://www.analogconsultants.com/