Why do racers stick out knee?

Question from my grandson.

Why do the Tour De France riders stick out their knee on a curve during
fast descents?

This was discussed at least once before as I recall but my search has come
up empty so far.

Thanks

On Aug 2, 3:28*pm, angusinalberta wrote:
Question from my grandson.

Why do the Tour De France riders stick out their knee on a curve during *
fast descents?

This was discussed at least once before as I recall but my search has come *
up empty so far.

Thanks

They're not sticking out their knees, they're raising the inside pedal
so it doesn't scrape the road.

They're not sticking out their knees, they're raising the inside pedal
so it doesn't scrape the road.

They are sticking out their knees, for the same reason motorcycle racers
stick out their knees.

rms

"rms" wrote: They are sticking out their knees, for the same reason
motorcycle racers
stick out their knees.
^^^^^^^^^^^^^^^^^
Since your answer does not include an answer, I'll say what I think is the
reason motorcycle racers stick out their knees. In a very fast turn, the
machine is leaned over so far that there is danger of grounding a footpeg.
The knee acts as a gauge to keep the rider from leaning too far. I'm not
sure that bicycles have a similar problem, since the rider keeps the inside
pedal at the top, as Bob W. has stated.

"Leo Lichtman" wrote in message
...

"rms" wrote: They are sticking out their knees, for the same
reason motorcycle racers
stick out their knees.
^^^^^^^^^^^^^^^^^
Since your answer does not include an answer, I'll say what I think is
the reason motorcycle racers stick out their knees. In a very fast
turn, the machine is leaned over so far that there is danger of
grounding a footpeg. The knee acts as a gauge to keep the rider from
leaning too far. I'm not sure that bicycles have a similar problem,
since the rider keeps the inside pedal at the top, as Bob W. has
stated.

Is that really why? That surprises me; sticking out a knee like that is
going to do bad things for aerodynamics, but then that might not be such
a bad thing in a corner anyway.

--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com

angusinalberta wrote:
Question from my grandson.

Why do the Tour De France riders stick out their knee on a curve
during fast descents?

They're "weighting" the inside to help make the turn. If they squeezed
their knees together or weighted the /outside/ knee, then they'd have to
lean the bike so much it would almost certainly slide out.

A certain infamous leaner's replies in this thread make absolutely no sense.
No idea why he'd say it's like putting a foot down; the pointed knee gets
the turn done faster, not slower.

BS

Why do the Tour De France riders stick out their knee on a curve
during fast descents?

They're "weighting" the inside to help make the turn. If they squeezed
their knees together or weighted the /outside/ knee, then they'd have to
lean the bike so much it would almost certainly slide out.

A certain infamous leaner's replies in this thread make absolutely no
sense. No idea why he'd say it's like putting a foot down; the pointed
knee gets the turn done faster, not slower.

^ This. Why did it take 7 replies in this thread to state the obvious?

rms

"rms" writes:

Why do the Tour De France riders stick out their knee on a curve
during fast descents?

They're "weighting" the inside to help make the turn. If they squeezed
their knees together or weighted the /outside/ knee, then they'd have to
lean the bike so much it would almost certainly slide out.

A certain infamous leaner's replies in this thread make absolutely no
sense. No idea why he'd say it's like putting a foot down; the pointed
knee gets the turn done faster, not slower.

^ This. Why did it take 7 replies in this thread to state the obvious?

rms

What is "obvious"? If someone asks a question I would suggest the answer
is not "obvious".

Simon Lewis wrote:
"rms" writes:

Why do the Tour De France riders stick out their knee on a curve
during fast descents?

They're "weighting" the inside to help make the turn. If they
squeezed their knees together or weighted the /outside/ knee, then
they'd have to lean the bike so much it would almost certainly
slide out.

A certain infamous leaner's replies in this thread make absolutely
no sense. No idea why he'd say it's like putting a foot down; the
pointed knee gets the turn done faster, not slower.

^ This. Why did it take 7 replies in this thread to state the
obvious?

rms

What is "obvious"? If someone asks a question I would suggest the
answer is not "obvious".

The OP's grandson asked a simple question. The answer is equally simple.

Bill "obviously" S.

On Aug 3, 10:12*am, "rms" wrote:
Why do the Tour De France riders stick out their knee on a curve
during fast descents?

They're "weighting" the inside to help make the turn. *If they squeezed
their knees together or weighted the /outside/ knee, then they'd have to
lean the bike so much it would almost certainly slide out.

A certain infamous leaner's replies in this thread make absolutely no
sense. No idea why he'd say it's like putting a foot down; the pointed
knee gets the turn done faster, not slower.

* * ^ This. *Why did it take 7 replies in this thread to state the obvious?

Because it's not "obvious," and it's not correct. IOW, Sornson is
wrong yet again.

"Weighting the inside" is nonsense. Sticking one's knee (or arm, or
whole body) to one side doesn't change the weight distribution. IOW,
it doesn't change the important factor in a turn, which is the
position of the center of mass relative to the tire contact patch.
For a given turn at a given speed, there is only one stable position
for the center of mass. If a knee is stuck out toward the inside, the
rest of the bike and body compensate for balance, by tilting toward
the outside. (The same thing happens if you do a track stand; to put
your knee right, you'd have to lean body+bike a bit left.)

Motorcycle racers have a different problem, as Jobst said. Their wide
machines can scrape metal before they lose traction, and scraping can
be hazardous. Hanging off the motorcycle toward the inside allows the
bike itself to be less tilted and less prone to scrape. And for many,
their knee protectors will lightly touch the pavement to allow them to
gauge how far they're leaning.

See http://stason.org/TULARC/vehicles/mo...side-Knee.html

or http://tinyurl.com/n6d5m8

Why do bicycle racers do it? ISTM it's just an instinct that produces
no benefit. If there is a benefit, it must be either some second-
order effect, or the minor amount of braking effect due to increased
air resistance.

- Frank Krygowski