deceptive slopes

State Road 600 (Plank Road) near Farmville, VA is like this. Heading
north out of town, the road, which appears flat to the eye, requires a
definite uphill pull. The grade is slight, but it's there and it's
long--several miles of it. Heading south toward town I feel like a
wind has come up behind me to push me home. This happens on short and
long rides, and no matter how tired or fresh I am. I have a
road-biased hybrid (don't yell at me--I'm saving for a good road bike):
14 mph going out, 22 mph coming back, even if I'm exhausted.

--
Rodney Dunning
Assistant Professor of Physics
Longwood University

recycled-one said:

Does anyone else have these?

I rode a section of highway I sometimes do as part of a 50 km out and in
that is part on-road and part off-road. The highway part is a typical two
lane black top with average inclines and declines to look at them. I haven't
measured them with an altimeter but my sense is that there is no drastic
bias in either direction. But my ride back always seems to require less
effort.

Ceterus paribus I would expect to be more tired coming back but these
highway slopes seem easier on the return leg.

Go figure.

"recycled-one" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Does anyone else have these?

I rode a section of highway I sometimes do as part of a 50 km out and in
that is part on-road and part off-road. The highway part is a typical two
lane black top with average inclines and declines to look at them. I
haven't measured them with an altimeter but my sense is that there is no
drastic bias in either direction. But my ride back always seems to require
less effort.

Ceterus paribus I would expect to be more tired coming back but these
highway slopes seem easier on the return leg.

Go figure.

"False Flats"
Yeah I have a few of those too. On one the trees nearby are angled slightly,
so that it makes it look flat, when you are really going up.
There is a hill with the optical illusion that makes it look not very steep,
but when you try to climb it, you find out it is a lot more steep than it
looks.

"recycled-one" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Does anyone else have these?

I rode a section of highway I sometimes do as part of a 50 km out and
in
that is part on-road and part off-road. The highway part is a typical
two lane black top with average inclines and declines to look at them.
I haven't measured them with an altimeter but my sense is that there
is no drastic bias in either direction. But my ride back always seems
to require less effort.

Ceterus paribus I would expect to be more tired coming back but these
highway slopes seem easier on the return leg.

Go figure.

Try and find out if your local government has bought into a publically
available GIS website, and you can see the elevation lines as one of the
layers, normally.

You might also find some hidden roadways or "I didn't know that went
through there" types of streets that could save a lot of angst in heavy
traffic conditions when you can't do a highway run.

"wvantwiller" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

"recycled-one" <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

Does anyone else have these?

I rode a section of highway I sometimes do as part of a 50 km out and
in
that is part on-road and part off-road. The highway part is a typical
two lane black top with average inclines and declines to look at them.
I haven't measured them with an altimeter but my sense is that there
is no drastic bias in either direction. But my ride back always seems
to require less effort.

Ceterus paribus I would expect to be more tired coming back but these
highway slopes seem easier on the return leg.

Go figure.

Try and find out if your local government has bought into a publically
available GIS website, and you can see the elevation lines as one of the
layers, normally.

You might also find some hidden roadways or "I didn't know that went
through there" types of streets that could save a lot of angst in heavy
traffic conditions when you can't do a highway run.

Oh I can do it easily enough. I wasn't even complaining about it really.
It's just something I noticed when I ride it. I'm sure an exact measurement
of the slopes would show that the outbound leg is a net incline.

I have noticed other - what I call - power inclines. Hills that seem
conducive to hard pedalling, actually accelerating uphill.

Optical illusion and para-normal causes aside, is it possible the wind
is behind you on the return (or against you on the outgoing) trip?
Sometimes the slightest breeze, although not physically noticed can have
the most annoying effect on "peformance"

- -
Comments and opinions compliments of,
"Your Friendly Neighborhood Wheelman"

My web Site:
http://geocities.com/czcorner

To E-mail me:
ChrisZCorner "at" webtv "dot" net

Chris Corner said:

Optical illusion and para-normal causes aside, is it possible the
wind is behind you on the return (or against you on the outgoing)
trip? Sometimes the slightest breeze, although not physically
noticed can have the most annoying effect on "performance"

To appreciate wind effects graphically, see:

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

The graphs show wind effects only, other losses being independent of
these. Adding mechanical losses to these graphs would obscure wind
effects.

Jobst Brandt

"Chris Z The Wheelman" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Optical illusion and para-normal causes aside, is it possible the wind
is behind you on the return (or against you on the outgoing) trip?
Sometimes the slightest breeze, although not physically noticed can have
the most annoying effect on "performance"

I thought about the wind first. It could be. I never measured but I suspect
if anything the prevailing winds would mostly come out of the west and the
return leg is from east to west.

wvantwiller said:

Try and find out if your local government has bought into a publically
available GIS website, and you can see the elevation lines as one of the
layers, normally.

No need for that. Just connect to the National Map, courtesy of the
USGS:

http://nmviewogc.cr.usgs.gov/viewer.htm

-Buck

Group: rec.bicycles.misc
Date: Mon, Aug 21, 2006, 10:57pm (EDT+4)
From: [email hidden]

Quoted message said:

To appreciate wind effects graphically,
see:

Quoted message said:

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

Quoted message said:

The graphs show wind effects only, other
losses being independent of these.\
Adding mechanical losses to these
graphs would obscure wind effects.

Quoted message said:

Jobst Brandt

Interesting article, I only glanced through it (I'll read it in greater
detail later) but a couple of things struck me:

1) He states that wind resistance at the wheel is greater because "parts
are moving twice as fast". Actuality, the top half is moving at twice
the relative velocity of the main body of the bike and rider, HOWEVER,
the bottom half is stationary relative to the ground. Wouldn't these
factors cancel out to some degree?

2) Climbing uphill is more daunting because the resistance is constant,
regardless of speed. The way I've experienced it, effort does increase
when climbing faster, maybe not at the square of velocity like wind
resistance, but it does take more effort.

Actually I find climbing to be less daunting. Probably because I can
actually see the "enemy", and there is the knowledge that in most cases
the uphill will eventually end and in 99% of the cases be followed by a
downhill. No such guarantees exist with headwinds. Also there is the
demoralisng feeling that "you KNOW you should be going faster than
this..." Therefore headwinds launch a psychological attack a wellas a
physical one.

But That's Just Me. :-3)

- -
Comments and opinions compliments of,
"Your Friendly Neighborhood Wheelman"

My web Site:
http://geocities.com/czcorner

To E-mail me:
ChrisZCorner "at" webtv "dot" net

Quoted message said:

1) He states that wind resistance at the wheel is greater because "parts
are moving twice as fast". Actuality, the top half is moving at twice
the relative velocity of the main body of the bike and rider, HOWEVER,
the bottom half is stationary relative to the ground. Wouldn't these
factors cancel out to some degree?

only if wind resistance is linear with velocity.
which it isn't.
--
mac the naïf

"Buck" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

wvantwiller said:

Try and find out if your local government has bought into a publically
available GIS website, and you can see the elevation lines as one of the
layers, normally.

No need for that. Just connect to the National Map, courtesy of the
USGS:

Nope. The problem lies in the first two initials.

Quoted message said:

http://nmviewogc.cr.usgs.gov/viewer.htm

There's a section of Route 29, along the Delaware River in New Jersey,
that rides like it's uphill in both directions! I've thought about the
wind shifting directions between the morning leg and the afternoon
return, but I haven't perceived any pattern. That 8½ mile stretch just
rides like a slight incline in either direction, north or south.
Regards, Roy Zipris

Chris Z The Wheelman said:

1) He states that wind resistance at the wheel is greater because "parts
are moving twice as fast". Actuality, the top half is moving at twice
the relative velocity of the main body of the bike and rider,

Not to nit pick, but only the top and bottom POINTS are going at twice
and zero the "over the road speed," not wheel halves.

Quoted message said:

2) Climbing uphill is more daunting because the resistance is constant,
regardless of speed. The way I've experienced it, effort does increase
when climbing faster, maybe not at the square of velocity like wind
resistance, but it does take more effort.

Work = Force x Distance. When climbing, the "force" is the weight of
you and the bike. The "distance" is the vertical rise. But climbing
faster, means you're doing the same work in less time which requires
more POWER.

Art Harris

Buck said:

wvantwiller said:

Try and find out if your local government has bought into a publically
available GIS website, and you can see the elevation lines as one of the
layers, normally.

No need for that. Just connect to the National Map, courtesy of the
USGS:

http://nmviewogc.cr.usgs.gov/viewer.htm

-Buck

Check out http://www.routeslip.com/. You can enter your routes using
an interactive map, and it determines elevations automatically. I'm
not sure what database it's using, but it appears accurate for the
areas around Farmville, VA and Birmingham, AL, places I'm familiar
with. You can also keep an online log of your rides. Cool site.

--
Rodney Dunning
Assistant Professor of Physics
Longwood University
http://www.longwood.edu/staff/dunningrb/