# 18% grade = what angle



## gutfiddle (Apr 27, 2006)

if a climb is 18% over 1/4 mile what is the angle from 0? how do u compute such angle? gracias.


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## asciibaron (Aug 11, 2006)

geometry is your friend...

if you know the starting elevation and the ending elevation, you can work out the average slope of the ascent using Pythagoras' Theorm (a^2+b^2=c^2) - the 18% grade was calculated by the rise over run formula.

from here you can calculate the tangent (the angle you want) by dividing the opposite (rise) by the adjacent (overall run). from here you will need to consult a trig table to get the ratio expressed as an angle

here's an example:

if you have a 1/4 mile climb that gains 132 feet, it equates to about a 6 degree slope angle


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## Argentius (Aug 26, 2004)

Well, a 100% grade is 45 degrees -- 1 foot up for every 1 foot out.
So, do the math on that. I think it's about 8 degrees.

Edit: yeah, 10.2 is the real math.


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## Dumbod (Dec 31, 2004)

asciibaron said:


> geometry is your friend...
> 
> if you know the starting elevation and the ending elevation, you can work out the average slope of the acsent using Pythagoras' Theorm (a^2+b^2=c^2)
> 
> the 18% grade was calculated by the rise over run formula.


Actually, while geometry is your friend, Pythagoras won't help. You need your old pal trigonometry to figure out the angle.

OR 

go to http://ostermiller.org/calc/triangle.html. By my calculations, the acutal angle is 10%.


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## asciibaron (Aug 11, 2006)

Dumbod said:


> Actually, while geometry is your friend, Pythagoras won't help. You need your old pal trigonometry to figure out the angle.
> 
> OR
> 
> go to http://ostermiller.org/calc/triangle.html. By my calculations, the acutal angle is 10%.


Pythagoras will most certainly help - you need to figure out the triangle before you can proceed to solve the trig part of the equation.


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## wasfast (Feb 3, 2004)

Remember that percentage is the amount of change over 100 feet. So 18 % is 18/100. The actual angle is 10.2 degrees. Doesn't sound like much angle compared to how hard is/looks when you're struggling up it.


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## asciibaron (Aug 11, 2006)

wasfast said:


> Remember that percentage is the amount of change over 100 feet. So 18 % is 18/100. The actual angle is 10.2 degrees. Doesn't sound like much angle compared to how hard is/looks when you're struggling up it.


not exactly - the 18% is calculated using rise over run - it has nothing to do with rise in 100ft - you can still have an 18% grade on a 25ft run (4.5/25=0.18) rise over run always works regardless of length. 2" of rise in 11" is an 18% grade.


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## Guest (Aug 2, 2007)

It's pretty simple. A 45 deg angle is a 100% grade since the road would rise 1 foot for every 1 foot travelled horizontally. So to figure the angle of the road, given the grade percentage, simply multiply 45deg by the grade percentage.

45deg x 18% = 8.1deg


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## gutfiddle (Apr 27, 2006)

so is it 10.2 or 8.1?


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## MikeBiker (Mar 9, 2003)

gutfiddle said:


> so is it 10.2 or 8.1?


Neither accounts for the curvature of the Earth.


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## Reynolds531 (Nov 8, 2002)

Bdaghisallo said:


> It's pretty simple. A 45 deg angle is a 100% grade since the road would rise 1 foot for every 1 foot travelled horizontally. So to figure the angle of the road, given the grade percentage, simply multiply 45deg by the grade percentage.
> 
> 45deg x 18% = 8.1deg


This is sad. I want to cry. I hope Kerry Irons and C40 don't see this thread.


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## twowheelMarc (Jul 11, 2003)

*its 10.2 degrees nm*

its 10.2 degrees nm


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## gutfiddle (Apr 27, 2006)

MikeBiker said:


> Neither accounts for the curvature of the Earth.


where does Pi fit in the equation?


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## Reynolds531 (Nov 8, 2002)

*end the geometry carnage*

Two simple steps

1. convert the percent grade into a decimal 18%=0.18

2. Take the inverse tangent of 0.18 = 10.2%


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## Fredke (Dec 10, 2004)

Bdaghisallo said:


> It's pretty simple. A 45 deg angle is a 100% grade since the road would rise 1 foot for every 1 foot travelled horizontally. So to figure the angle of the road, given the grade percentage, simply multiply 45deg by the grade percentage.
> 
> 45deg x 18% = 8.1deg


This is so wrong. First, percentage grade is the vertical rise divided by the road distance, not the horizontal distance. 100% grade is 90 degrees. 45 degrees is 71%.

Second, the sine of an angle is not proportional to the angle, so you can't get the angle by multiplying 90 degrees by the percentage grade.

To get the angle you take the inverse sine (or arcsine) of the grade: 18% = 0.18. arcsin(0.18) = 0.18 radians = 10.3 degrees


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## asciibaron (Aug 11, 2006)

Bdaghisallo said:


> It's pretty simple. A 45 deg angle is a 100% grade since the road would rise 1 foot for every 1 foot travelled horizontally. So to figure the angle of the road, given the grade percentage, simply multiply 45deg by the grade percentage.
> 
> 45deg x 18% = 8.1deg


an 18% grade is 10.4 degrees. the ratio of rise over run is the tangent - on a trig table the ratio .18 = 10.4 degrees.


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## Reynolds531 (Nov 8, 2002)

gutfiddle said:


> where does Pi fit in the equation?


Raise the base of the natural log,e, to the imaginary number i times pi. add 1. add this value to the inverse tangent of the gradient expressed as a decimal. This will give you the degrees from horizontal: e^(i*pi) + 1 + invtan(gradient/100)


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## gutfiddle (Apr 27, 2006)

arctan0.18=10.2 thus at 46% humidity, 12 mph wind and clean body geometry socks i will be able to climb the bear wallow mtn.


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## asciibaron (Aug 11, 2006)

thanks Fredke - it's been a few decades since i took a math class - my coffee hadn't kick kicked in on my first poast. it finally kicked in and the lightbulb went off while you were typing

paise *insert your deity of choice* for caffiene


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## innergel (Jun 14, 2002)

math threads are so hawt right now


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## twowheelMarc (Jul 11, 2003)

Sorry Fredke, a 90 degree angle (a cliff) has an infinite slope.

Taken from :http://draco.acs.uci.edu/rbfaq/FAQ/9.3.html

The grade of an incline is its vertical rise, in feet, per every 100 horizontal
feet traversed. (I say "feet" for clarity; one could use any consistent
length measure.) Or, if you will accept my picture below,

*
d |
a |
o | y
R |
*___)______|
x
then
Grade = y/x (Multiply by 100 to express as a percentage.)
and
Theta = arctan(y/x)

So a grade of 100% is a 45 degree angle. A cliff has an infinite grade.


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## gutfiddle (Apr 27, 2006)

I'm takin an angle finder on the ride to check teh math


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## Reynolds531 (Nov 8, 2002)

twowheelMarc said:


> Sorry Fredke, a 90 degree angle (a cliff) has an infinite slope.
> 
> Taken from :http://draco.acs.uci.edu/rbfaq/FAQ/9.3.html
> 
> ...


This is a very rare instance when Fredke isn't 100% right. Hhowever, his method is quite widely used and is a very close appoximation for the small angle inclines on roads.


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## Eric S (Mar 29, 2006)

I can't follow this math, I have a simple question. I plan to climb the Hyde Park Road In Santa Fe NM. This is the road from town to the ski area. It rises 3,250 feet in 15 miles. What is the grade and what is the angle?

Also, I am a flatlander who rides a 50/34 with a 11/23 cassette. I plan to change to a 12/27 cassette for this climb. Will I make it? 

Second question is a joke (sort of).


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## mohair_chair (Oct 3, 2002)

gutfiddle said:


> so is it 10.2 or 8.1?


Are we talking radians or degrees?


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## bikeboy389 (May 4, 2004)

Eric S said:


> I can't follow this math, I have a simple question. I plan to climb the Hyde Park Road In Santa Fe NM. This is the road from town to the ski area. It rises 3,250 feet in 15 miles. What is the grade and what is the angle?
> 
> Also, I am a flatlander who rides a 50/34 with a 11/23 cassette. I plan to change to a 12/27 cassette for this climb. Will I make it?
> 
> Second question is a joke (sort of).


Rise over run says that's about a 4% grade. I'm not good enough at math to figure the angle, but it's probably not worth measuring. I wouldn't even change the cassette for that "climb," seeing as you have a compact. Now if you're also a lowlander as well as a flatlander, then the altitude might give you some trouble, but a 4% grade probably won't.

This assumes, of course, that I've figured the grade properly, which is not necessarily a given with me.


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## gutfiddle (Apr 27, 2006)

I concur, 4.1%, if you cant climb that w/ a compact crank then well...


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## bikeboy389 (May 4, 2004)

gutfiddle said:


> I concur, 4.1%, if you cant climb that w/ a compact crank then well...


Of course, it's possible that it's flat most of the way, and 15% at the end.


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## Eric S (Mar 29, 2006)

gutfiddle said:


> I concur, 4.1%, if you cant climb that w/ a compact crank then well...


Thanks for the respones Bikerboy and Gutfiddle. Thais road is from 7,000 to 10,250 feet with down hills as well as long climbs, not just as simple as 3,250 over 15 miles. I train at sea level.I would rather have the small gears if I need them.


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## JCavilia (Sep 12, 2005)

*Bring the low gears*



Eric S said:


> Thanks for the respones Bikerboy and Gutfiddle. Thais road is from 7,000 to 10,250 feet with down hills as well as long climbs, not just as simple as 3,250 over 15 miles. I train at sea level.I would rather have the small gears if I need them.


Any idea what the steepest pitches are? That matters more than the average grade. 4% average grade is not too steep, but since the road has ups and downs it may have many sections that are much steeper.

If I were you I'd seriously think about putting on a triple, but maybe 34/27 will be enough. Since you live at sea level, you'll probably feel the altitude even at the start, and you'll certainly feel it at the top. 

I climbed the Haleakala volcano on Maui a few years ago. The road goes from sea level to 10,000 feet in a continuous 38-mile climb, which is around 5%. It's a very steady climb, so there's very little that's much steeper than that. I can normally climb a short 5% climb in a 39/21 or higher, but the long distance makes a difference,as does the altitude. I live at sea level, but I grew up at about 5,000 feet, and I acclimate pretty quickly. My rental bike had a triple, and I was very grateful to have that little ring.


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## Eric S (Mar 29, 2006)

JCavilia said:


> Any idea what the steepest pitches are? That matters more than the average grade. 4% average grade is not too steep, but since the road has ups and downs it may have many sections that are much steeper.
> 
> If I were you I'd seriously think about putting on a triple, but maybe 34/27 will be enough. Since you live at sea level, you'll probably feel the altitude even at the start, and you'll certainly feel it at the top.
> 
> I climbed the Haleakala volcano on Maui a few years ago. The road goes from sea level to 10,000 feet in a continuous 38-mile climb, which is around 5%. It's a very steady climb, so there's very little that's much steeper than that. I can normally climb a short 5% climb in a 39/21 or higher, but the long distance makes a difference,as does the altitude. I live at sea level, but I grew up at about 5,000 feet, and I acclimate pretty quickly. My rental bike had a triple, and I was very grateful to have that little ring.


I just kown that there are some pretty good sustained pitches on the road. I spend about 35 days a year there and I run and do some mountian biking there so I know what to expect with the altitude.I don't think I need the triple but I'll feel better knowing I have the 34/27 if I need it.


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## asciibaron (Aug 11, 2006)

Eric S said:


> It rises 3,250 feet in 15 miles. What is the grade and what is the angle?


4% overall - i'm sure it's not constant.


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## bikeboy389 (May 4, 2004)

Eric S said:


> I just kown that there are some pretty good sustained pitches on the road. I spend about 35 days a year there and I run and do some mountian biking there so I know what to expect with the altitude.I don't think I need the triple but I'll feel better knowing I have the 34/27 if I need it.


If you're able, as a lowlander, to mountain bike in the Santa Fe area without having a brain hemmorage, you'll probably be OK with the altitude indeed. I've only been MTB'ing there once, and I thought my eyes were gonna pop out. I'm not used to the MTB, and at 7K feet, it was just a nightmare. I live at 300 feet above sea level, and the altitude change busts me up for a couple of days at least.


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## mick wolfe (Feb 15, 2004)

gutfiddle said:


> so is it 10.2 or 8.1?



Put your money on 10.2 as many have already noted. Arctan of 18 over 100 or .18 = 10.204


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## rogger (Aug 19, 2005)

gutfiddle said:


> if a climb is 18% over 1/4 mile what is the angle from 0? how do u compute such angle? gracias.


Why would you want to know the angle? 18% equals small ring times big cog to the power of painful legs plus heart exploding.


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## gutfiddle (Apr 27, 2006)

rogger said:


> Why would you want to know the angle? 18% equals small ring times big cog to the power of painful legs plus heart exploding.


b/c i like to analyze everything to deth and psych myself all up in preparation for the suffering


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## Forrest Root (Dec 22, 2006)

With the display of math skills shown here, I weep for the future. Now I know why US companies are shipping jobs overseas: they want people who can do math to do the work.


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## Kerry Irons (Feb 25, 2002)

*I am the Walrus*



Reynolds531 said:


> This is sad. I want to cry. I hope Kerry Irons and C40 don't see this thread.



Mister City P'liceman sitting
Pretty little policemen in a row.
See how they fly like Lucy in the Sky, see how they run.
I'm crying. I'm cry------------ing,
I'm crying. I'm cry------------ing.


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## Guest (Aug 2, 2007)

*Hallelujah!!*



rogger said:


> Why would you want to know the angle? 18% equals small ring times big cog to the power of painful legs plus heart exploding.


Thanks rogger - first response to this thread that doesn't give me a migrane! And practical to boot.

Bill


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## Climbing_Clyde (Jun 16, 2007)

*HOLY FAWKING TRAIN CRASH BATMAN!!*


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## estone2 (Sep 25, 2005)

bikeboy389 said:


> Rise over run says that's about a 4% grade. I'm not good enough at math to figure the angle, but it's probably not worth measuring. I wouldn't even change the cassette for that "climb," seeing as you have a compact. Now if you're also a lowlander as well as a flatlander, then the altitude might give you some trouble, but a 4% grade probably won't.
> 
> This assumes, of course, that I've figured the grade properly, which is not necessarily a given with me.


I dunno. Lowlanders do fine with altitude if they're cyclists, in my experience.

I went up to Colorado, from 750 to like 6500. I climbed up to 11... 12k. I think 12232 was the highest I got. I was breathing just fine. The air was a different quality, but I felt fine.

That being said, I have a freakish VO2Max, due to my age probably


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## Tugboat (Jul 17, 2006)

<cough> Nerds!


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## Reynolds531 (Nov 8, 2002)

Tugboat said:


> <cough> Nerds!


You flatter us with your praise!


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## bismo37 (Mar 22, 2002)

Wait a minute, guys.... Is the African swallow in question laden or unladen? Did you account for this?


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## Guest (Aug 3, 2007)

Whoops! I stand corrected!


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## Climbing_Clyde (Jun 16, 2007)

Are you suggesting coconuts migrate?


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## Dumbod (Dec 31, 2004)

*Related Question*

John has thee apples, Mary has three oranges. They get on a train going due east at 45mph. When they off the train, Mary has four organges and John has a coconut. What time is it?


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## asciibaron (Aug 11, 2006)

Dumbod said:


> John has thee apples, Mary has three oranges. They get on a train going due east at 45mph. When they off the train, Mary has four organges and John has a coconut. What time is it?


*in Rodney Dangerfield voice* 

4?

too obscure?


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## ralph1 (May 20, 2006)

*Angle*

My head hurts....... 

cheers

Ralph


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## Fredke (Dec 10, 2004)

twowheelMarc said:


> Sorry Fredke, a 90 degree angle (a cliff) has an infinite slope.


Thanks for the correction. You're right. I usually check my facts more carefully before posting. Thanks again for setting me straight.


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## TurboTurtle (Feb 4, 2004)

Forrest Root said:


> With the display of math skills shown here, I weep for the future. Now I know why US companies are shipping jobs overseas: they want people who can do math to do the work.


And half of the posters are probably the MBAs that are deciding where those jobs should be. - TF


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## Mayday (Jan 22, 2004)

(Quote) So a grade of 100% is a 45 degree angle. A cliff has an infinite grade.

Just curious ... If a 45-degree angle equals 100% slope, what is the percent slope of a 50-degree angle, or 60?


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## asciibaron (Aug 11, 2006)

Mayday said:


> Just curious ... If a 45-degree angle equals 100% slope, what is the percent slope of a 50-degree angle, or 60?


50 = 119%
60 = 173%

maybe.


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## Forrest Root (Dec 22, 2006)

TurboTurtle said:


> And half of the posters are probably the MBAs that are deciding where those jobs should be. - TF


*THAT* I believe. Who needs to know math when you've got a calculator or an assistant with a calculator?:mad2:


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## serious (May 2, 2006)

Forest Root: *With the display of math skills shown here, I weep for the future*

No kidding. BTW, the easy way to go from grade to degree is to divide by 2. It is an APPROXIMATION, but good enough if you don't have a calculator. So 18% would be approximately 9 degrees (10.2 to be exact). 35% would be about 18 degrees, 70% would be about 35 degrees and so on.

It is funny when people confuse the two. I've had skiers swear that they skied 70 degree slopes. Of course they meant 70% grade (about 35 degrees), which is fairly steep, but no big deal for a good skier. But on a 70 degree slope, snow would have trouble hanging on.


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## estone2 (Sep 25, 2005)

Forrest Root said:


> With the display of math skills shown here, I weep for the future. Now I know why US companies are shipping jobs overseas: they want people who can do math to do the work.


Hey man,
You shouldn't be weeping for the future. Those are adults.

Us kids aren't that incompetent at math!


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## Mdeth1313 (Nov 1, 2001)

asciibaron said:


> an 18% grade is 10.4 degrees. the ratio of rise over run is the tangent - on a trig table the ratio .18 = 10.4 degrees.



wait a minute-- you have a trig table? didnt those go out w/ the graphing calculator?


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## timmyc (Mar 21, 2006)

*of course...*

of course African swallows are nonmigratering.


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## fabsroman (Jul 14, 2006)

Nothing better than a headache to start off the morning. Thanks guys.

Would a cliff have a 200% grade with a 90 degree angle, or would it actually be infinite, because it being infinite doesn't make sense to me.


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## twowheelMarc (Jul 11, 2003)

Think of it in the context of earning money. Let's start by assuming you get paid $10/per hour. Now lets say you were to get a raise, but instead of thinking about an increased dollar amout per hour, lets think about the same dollars but for a reduced amount of time. Lets say the raise is $10 per half hour ($20 per hour) if you keep going like this the example becomes clear very quickly. Say you get a raise again, to $10 per 15 minutes ($40 per hour) and keep going $10 per 5 minutes ($120 per hour), $10 per 1 minute ($600/ hr.). As you begin to approach $10 pay for no time at all you will see what happens. $10 per 1 second ($36,000 per hour), $10 per 1/10 of a second $360,000/hr, now if you got $10 for no time at all you have an infinite amount of money because you would keep getting $10 but time would never move.

This applies to the slope because the % is the distance traveled up (or down) versus the distance traveled forward (or backward) so if you travel up on a cliff, you will be moving up but never forward so in theory you could travel straight up forever and never travel an inch forward, thus an infinite slope.

Hope i didn't make it more confusing.


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## gutfiddle (Apr 27, 2006)

so I make more money the steeper the climbs on a century ride or the same amount of money just in a shorter period of time?!? awesome i could use the extra bread.


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## estone2 (Sep 25, 2005)

fabsroman said:


> Nothing better than a headache to start off the morning. Thanks guys.
> 
> Would a cliff have a 200% grade with a 90 degree angle, or would it actually be infinite, because it being infinite doesn't make sense to me.



90 degree angle causes it to be not infinite, but *undefined*. big difference. The percentage is rise over run. A 10% grade - up 10 feet for every 100feet over, ya?

90 degrees - up... a lot of feet, over... 0. To get the percentage - (integer climbed)/(integer horizontally traversed). At 90 degrees, (int hor trav) is 0. (any integer)/0=undefined.

-estone2


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## JohnnyTooBad (Apr 5, 2004)

fabsroman said:


> Nothing better than a headache to start off the morning. Thanks guys.
> 
> Would a cliff have a 200% grade with a 90 degree angle, or would it actually be infinite, because it being infinite doesn't make sense to me.


It's not infinite or 200%. It's an "empty set", or basically, null or n/a. The math is rise / run, and run is 0, it's a divide-by-zero error, since you can't divide by zero.

I guess it's no longer a slope, but a vertical line?


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## twowheelMarc (Jul 11, 2003)

Maybe we should avoid the "zero" discussion and just calculate the slope if the angle was 89.9999999999999999999999999999999999999999999999999999999999 degrees.

Approaching zero is the key here (in my opinion).


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## John Nelson (Mar 10, 2006)

Although the grade of a 90-degree slope is undefined, it might be interesting to look at the grades of slopes approaching 90 degrees.

The grade of an 80-degree slope is 567%.
The grade of an 89-degree slope is 5,729%.
The grade of an 89.9-degree slope is 57,296%.
The grade of an 89.99-degree slop is 572,958%.


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## Mark McM (Jun 18, 2005)

John Nelson said:


> Although the grade of a 90-degree slope is undefined, it might be interesting to look at the grades of slopes approaching 90 degrees.
> 
> The grade of an 80-degree slope is 567%.
> The grade of an 89-degree slope is 5,729%.
> ...


What's the angle of a slope with a grade of a googolplex% ?


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## light_monkey (Apr 27, 2005)

*grade of googolplex*



Mark McM said:


> What's the angle of a slope with a grade of a googolplex% ?


I'm usually a lurker, but I will make an exception.

summary so far...
% grade = slope = change in vertical distance divided by change in horizontal distance (rise/run)

you may remember learning in Trigonometry class that tangent of an angle is equal to slope. hence, an angle is equal to arctan of the slope.

now, as slope increases towards infinity, angle simply *approaches* 90 degrees.

in order for the angle to be EXACTLY 90 degrees, slope (or % grade) is undefined.


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## Sweet Milk (Oct 13, 2004)

To really get to a proper answer you need to take into account the progression of gravity equipotential fields that the center of mass propagates through, a little over the top maybe  

Reading this thread I see why people are worried about the level of math education :mad2:


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## JohnHemlock (Jul 15, 2006)

Corn on the cob is good, isn't it?


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## fabsroman (Jul 14, 2006)

I don't know the answer to the question, but what really kills me is that every time I read a thread on this board dealing with something mathematical or scientific, there doesn't seem to be a single concise answer that everybody can agree on. Heck, 2+2 doesn't even equal 4 on this board.

With that said, I still have no idea what % grade means. I had always thought that it meant rise over run and that a 100% grade would go up 1 foot for every horizontal foot travelled, but now I have no idea if that is even right.


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## Pablo (Jul 7, 2004)

fabsroman said:


> I don't know the answer to the question, but what really kills me is that every time I read a thread on this board dealing with something mathematical or scientific, there doesn't seem to be a single concise answer that everybody can agree on. Heck, 2+2 doesn't even equal 4 on this board.


And the scientists give us lawyers a hard time. Ha!


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## DrSmile (Jul 22, 2006)

I prefer negative grades... what would the rise be if I threw my bike off a cliff?


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## fabsroman (Jul 14, 2006)

Pablo,

Wait until you have a trial where you have a bunch of "scientists" as experts and each one of them has a different opinion that suits their respective client. Utterly amazing. Talk about 2+2 not equaling 4.

All I know is that I am going to continue to use my Garmin Edge 305 to determine %grade and just assume that the higher the number the tougher the climb. Plain and simple. I'll let the Garmin deal with the math.


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## Bianco (Sep 22, 2004)

Why does PERCENT even matter? What is the history of using percent? Why not just use angle when speaking of slope...


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## Pablo (Jul 7, 2004)

fabsroman said:


> Pablo,
> 
> Wait until you have a trial where you have a bunch of "scientists" as experts and each one of them has a different opinion that suits their respective client. Utterly amazing. Talk about 2+2 not equaling 4.
> 
> All I know is that I am going to continue to use my Garmin Edge 305 to determine %grade and just assume that the higher the number the tougher the climb. Plain and simple. I'll let the Garmin deal with the math.


You should hear water engineers at trial. The stream is flooded or dry depending on the client. 

Personally, I'll let me legs determine how hard a climb is an leave the math to the sophists.


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## Mark McM (Jun 18, 2005)

*Percent grade - it is more practical and just makes more sense than angle*



Bianco said:


> Why does PERCENT even matter? What is the history of using percent? Why not just use angle when speaking of slope...


Percent grade is used because it just makes more sense than angles:

- It is easier to calculate (just divide rise by run - no non-linear trigonometric functions are necessary).

- It it easier to deal with (if you are building a ramp, and you want to change the grade, you just lift the end by a linear multiple).

The slopes of roadways, trails, railroads, water sluices, etc. have always been measured in percent grade (not angles) since the times that they started to build them.


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## filtersweep (Feb 4, 2004)

Or riding with crampon tires--- under a grade "greater" than 90 degrees, upside down?



DrSmile said:


> I prefer negative grades... what would the rise be if I threw my bike off a cliff?


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