grade/slope/etc

Charles Beristain <[email hidden]> wrote in
news:[email hidden]:

Quoted message said:

I realize this has been discussed many times before, but I can't seem
to find the info. how does one calculate grade/slope?

Ascutney .. 2150 change in elevation, road is 3.8 miles.

Grade is vertical/horizontal * 100.
Your grade is 10.7%, which is a pretty nice hill.

Charles Beristain said:

I realize this has been discussed many times before, but I can't seem
to find the info. how does one calculate grade/slope?

Ascutney .. 2150 change in elevation, road is 3.8 miles.

thanks

charlieb

Dear Charles,

For the average grade between two points, divide the rise by
the run.

A ten-foot rise in a hundred feet is a 10% grade.

2150 / (3.8 * 5280 ) = 2150 / 20,064 = 10.7% grade

Carl Fogel

Charles Beristain said:

I realize this has been discussed many times before, but I can't seem
to find the info. how does one calculate grade/slope?

Ascutney .. 2150 change in elevation, road is 3.8 miles.

thanks

charlieb

Dear Charles,

An alternative method is to go to a site for New England
bicycle climbs like this:

http://home.sprintmail.com/~dsjansen/Mtn_Climbs.html

It shows Ascutney at 2,266 feet of rise in 3.7 miles for an
11.7% average grade with one section as steep as 19.7%.

Carl Fogel

carlfogel said:

For the average grade between two points, divide the rise by the run.

A ten-foot rise in a hundred feet is a 10% grade.

Well, sort of. The % grade of a hill is the rise divided by the
horizontal distance (as a fraction; multiply by 100 for the percentage),
not the distance along the hill. The difference is small on any hill
anyone could climb, but a 45-degree slope is a 100% grade, whereas rise
divided by run along the road would be 0.7.

--

David L. Johnson

__o | The lottery is a tax on those who fail to understand
_`\(,_ | mathematics.
(_)/ (_) |

David L. Johnson said:

carlfogel said:

For the average grade between two points, divide the rise by the run.

A ten-foot rise in a hundred feet is a 10% grade.

Well, sort of. The % grade of a hill is the rise divided by the
horizontal distance (as a fraction; multiply by 100 for the percentage),
not the distance along the hill. The difference is small on any hill
anyone could climb, but a 45-degree slope is a 100% grade, whereas rise
divided by run along the road would be 0.7.

Dear David,

Using Charles's example of Ascutney with 2,150 feet of climb
in 3.8 miles of road, the difference between the two methods
of calculation amounts my 10.716% versus your more accurate
method's 10.778%.

Most sites like these . . .

http://home.sprintmail.com/~dsjansen/Mtn_Climbs.html

http://212.98.32.192/salite/default.asp?Ultime=3

http://www.ulb.ac.be/di/ssd/ldoyen/e/v.html

.. . . take the easy way out and simply divide road distance
by elevation gain instead of working out the details of
long, skinny right triangles. The method used to calculate
grade % in the bicycling world is usually odometer distance
divided by elevation gain.

In any case, both methods are inaccurate in that they use
the road distance as if it were a straight-line hypotenuse,
even though roads actually roller-coaster upward at varying
slopes.

Thus the 3.8 figure is probably slightly exaggerated. A
laser beam from the bottom to the top of a 3.8 mile bicycle
climb will almost certainly travel a shorter distance than
the actual path of the wheel.

Carl Fogel

Quoted message said:

David L. Johnson said:

carlfogel said:

For the average grade between two points, divide the rise by the run.

A ten-foot rise in a hundred feet is a 10% grade.

Well, sort of. The % grade of a hill is the rise divided by the
horizontal distance (as a fraction; multiply by 100 for the percentage),
not the distance along the hill. The difference is small on any hill
anyone could climb, but a 45-degree slope is a 100% grade, whereas rise
divided by run along the road would be 0.7.

Dear David,

Using Charles's example of Ascutney with 2,150 feet of climb
in 3.8 miles of road, the difference between the two methods
of calculation amounts my 10.716% versus your more accurate
method's 10.778%.

This is another one of those significant figure things too. Those
extra digits to the right of the decimal point are meaningless. You
might as well make them up.

--
Let me finish! Want some wood?

"Jim Smith" wrote: This is another one of those significant figure things
too. Those extra digits to the right of the decimal point are meaningless.
You might as well make them up.
^^^^^^^^^^^^^^^
Since we are all in agreement that either method of calculation is "close
enough for highway work," let me bring in another little nit. If the run
(horizontal distance) is obtained from a map, then it WILL BE the horizontal
projection of the travel. If it is obtained from an odometer reading, then,
technically, it needs to be corrected. And, of course, as you point out, if
the correction is smaller than the accuracy of the data, it is meaningless.

thanks all for the info... we did Ascutney last thursday as a trial
run to see if we were capable of attempting mt. washington next year.
that has an ave of 12% and extended sections of 18% with the last 50
yards at 22%...

I struggled up Ascutney with a 29T front and a 29T rear. From what
I've heard, one should do Ascutney twice to get about the same
distance as mt. washington and then add one extra gear for the
increase in difficulty.
I've got a lot of training and weight loss to do between now and next
august if i'm going to attempt it. I suspect I'll be the oldest entry.

looks like I'll have to get a shimano compatible rear wheel and put a
34T cassette on it and make some other changes to have it work with
the campy shifter/derailleur in order to get lower than a 29t f and
29t rear.

charlieb in ct.

Quoted message said:

Charles Beristain said:

I realize this has been discussed many times before, but I can't seem
to find the info. how does one calculate grade/slope?

Ascutney .. 2150 change in elevation, road is 3.8 miles.

thanks

charlieb

Dear Charles,

An alternative method is to go to a site for New England
bicycle climbs like this:

http://home.sprintmail.com/~dsjansen/Mtn_Climbs.html

It shows Ascutney at 2,266 feet of rise in 3.7 miles for an
11.7% average grade with one section as steep as 19.7%.

Carl Fogel

Leo Lichtman said:

"Jim Smith" wrote: This is another one of those significant figure things
too. Those extra digits to the right of the decimal point are meaningless.
You might as well make them up.
^^^^^^^^^^^^^^^
Since we are all in agreement that either method of calculation is "close
enough for highway work," let me bring in another little nit. If the run
(horizontal distance) is obtained from a map, then it WILL BE the horizontal
projection of the travel. If it is obtained from an odometer reading, then,
technically, it needs to be corrected. And, of course, as you point out, if
the correction is smaller than the accuracy of the data, it is meaningless.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

....which it will be for nearly every paved road, and most unpaved ones.
20% by David's method is 19.6% by the rise/(road length) method. I
seriously doubt anyone without precision instruments could detect a 0.4%
difference in the vicinity of 20% grade.

The difference between the methods is far less at grades we encounter
more normally.

Mark Janeba

Charles Beristain said:

thanks all for the info... we did Ascutney last thursday as a trial
run to see if we were capable of attempting mt. washington next year.
that has an ave of 12% and extended sections of 18% with the last 50
yards at 22%...

I struggled up Ascutney with a 29T front and a 29T rear. From what
I've heard, one should do Ascutney twice to get about the same
distance as mt. washington and then add one extra gear for the
increase in difficulty.
I've got a lot of training and weight loss to do between now and next
august if i'm going to attempt it. I suspect I'll be the oldest entry.

looks like I'll have to get a shimano compatible rear wheel and put a
34T cassette on it and make some other changes to have it work with
the campy shifter/derailleur in order to get lower than a 29t f and
29t rear.

charlieb in ct.

Quoted message said:

Charles Beristain said:

I realize this has been discussed many times before, but I can't seem
to find the info. how does one calculate grade/slope?

Ascutney .. 2150 change in elevation, road is 3.8 miles.

thanks

charlieb

Dear Charles,

An alternative method is to go to a site for New England
bicycle climbs like this:

http://home.sprintmail.com/~dsjansen/Mtn_Climbs.html

It shows Ascutney at 2,266 feet of rise in 3.7 miles for an
11.7% average grade with one section as steep as 19.7%.

Carl Fogel

Dear Charles,

It's those charming little steep sections that stick out
from the average grade that require the lower gears and
heaving.

Good luck in August,

Carl Fogel

RE/

Quoted message said:

looks like I'll have to get a shimano compatible rear wheel and put a
34T cassette on it and make some other changes to have it work with
the campy shifter/derailleur in order to get lower than a 29t f and
29t rear.

Alternatively, you could go to an internally-geared hub.

With my Rohloff and a 32 chainwheel I go from 14.5 inches as my low to 76.3.
Probably sounds ridiculous - and I probably could move up to 16.4 as my low and
never really miss the 14.5...but I'm spun out at about 25 with 76.3; there's no
way I can hold 25 for any length of time anyhow; and I'm glad to have the 14.5
on, say, 40-degree grassy incline.
--
PeteCresswell

On Mon, 11 Oct 2004 01:08:57 GMT, "(Pete Cresswell)" <[email hidden]>

Quoted message said:

RE/

Quoted message said:

looks like I'll have to get a shimano compatible rear wheel and put a
34T cassette on it and make some other changes to have it work with
the campy shifter/derailleur in order to get lower than a 29t f and
29t rear.

Alternatively, you could go to an internally-geared hub.

With my Rohloff and a 32 chainwheel I go from 14.5 inches as my low to 76.3.
Probably sounds ridiculous - and I probably could move up to 16.4 as my low and
never really miss the 14.5...but I'm spun out at about 25 with 76.3; there's no
way I can hold 25 for any length of time anyhow; and I'm glad to have the 14.5
on, say, 40-degree grassy incline.

Dear Pete,

Perhaps it's a typo? Or a joke that sneaked past me?

But wouldn't a 40-degree incline, with or without grass, be
about an 84% grade (roughly 83.90995% as calculated by
David's correct method for Jim's sake) and just a bit
steeper than most bicyclists can climb?

(A 40% grade, on the other hand, would be about 21.8 degrees
and plausible on a bicycle for a short stretch.)

Degrees, grades . . . I feel quite nostalgic.

Carl Fogel

In article <[email hidden]>, Charles Beristain
says...

Quoted message said:

thanks all for the info... we did Ascutney last thursday as a trial
run to see if we were capable of attempting mt. washington next year.

Slightly off topic but Mt. Washington races are close to providing an answer to
a question that has been debated on this news group: at what grade is a runner
faster than a bicycle. There are races up Mt. Washington for both plus
motorized vehicles. Bicycles are faster than runners up Mt. Washington but not
by much.

RE/

Quoted message said:

Perhaps it's a typo? Or a joke that sneaked past me?

Definately not an actual measurement - more like a figure of speech.... but the
grade I had in mind was one of those where, if your foot comes loose from a
pedal or something, your first concern is going over backwards.
--
PeteCresswell