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Keep The Rubber Side Down
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Got this in an eMail today. Thought it was interesting:

Grade = steepness of hill*

Most of us find that climbing up a 200-foot hill which is steep takes more out of us than a 200-foot hill which is gentle.* A simple and very useful measure of steepness is "grade":

grade = vertical climb / horizontal distance

where both vertical climb and horizontal distance are both converted to the same measurement units.* So if a hill goes up 264 feet in 2 miles, then we can first convert 2 miles to 10560 feet -- so the grade is then 0.025 = 264 feet / 10560 feet, which is 2.5%.**

What does this "grade" number mean?**
0% grade is exactly flat (and a negative grade, less then zero, is downhill).**
2% grade does not seem very steep, but it's enough to substantially reduce forward speed, and for most riders it will absorb more than half their power output.**
6% grade is enough to cut speed to well under half, and absorb more than 80% of a rider's power output (leaving less than 20% to fight air resistance and rolling friction).**
10% grade, and anyone who is not a fit and frequent rider is off their bike walking -- and anyone who is not a racer is reaching for all the extra power they've got.*
 

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cool

Great explanation! That's a good description of why few mtbike trails sustain anything 6% or greater. 10% is brutal indeed.

Mellow Yellow said:
Got this in an eMail today. Thought it was interesting:

Grade = steepness of hill*

Most of us find that climbing up a 200-foot hill which is steep takes more out of us than a 200-foot hill which is gentle.* A simple and very useful measure of steepness is "grade":

grade = vertical climb / horizontal distance

where both vertical climb and horizontal distance are both converted to the same measurement units.* So if a hill goes up 264 feet in 2 miles, then we can first convert 2 miles to 10560 feet -- so the grade is then 0.025 = 264 feet / 10560 feet, which is 2.5%.**

What does this "grade" number mean?**
0% grade is exactly flat (and a negative grade, less then zero, is downhill).**
2% grade does not seem very steep, but it's enough to substantially reduce forward speed, and for most riders it will absorb more than half their power output.**
6% grade is enough to cut speed to well under half, and absorb more than 80% of a rider's power output (leaving less than 20% to fight air resistance and rolling friction).**
10% grade, and anyone who is not a fit and frequent rider is off their bike walking -- and anyone who is not a racer is reaching for all the extra power they've got.*
 

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Ride what you want!!
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Mellow Yellow said:
Got this in an eMail today. Thought it was interesting:

Grade = steepness of hill*
What's really fun is when you convert %grade to degrees. So a 10% grade, which hurts, is actually 4.5 degrees. How many times have you heard someone talking about a 45 degree slope they just climbed... 45 degrees = 100% grade.

george
 

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Ride what you want!!
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Stick said:
Aw, c'mon, M.Y., that's like junior high geometry!
:D

You want grade? You can't handle the grade!!!!

check out mile 52.4
Hell, it's only .3 miles long.. We've got a little local section that floats between 14% and up to 18% for a good mile. Then there is the county line climb which averages 12% for 2 miles.

george
 

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pedaller
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Close, but no cigar Mellow Yellow!!!!!!

grade = vertical climb / horizontal distance....So if a hill goes up 264 feet in 2 miles, then we can first convert 2 miles to 10560 feet -- so the grade is then 0.025 = 264 feet / 10560 feet, which is 2.5%.**
ohhhh so close....(your formula is right but not the measurements)

In common practice, people often refer to percent grade as the rise divided by the distance you would travel going up the hill, rather than the horizontal distance. If you have an odometer and an altimeter, this is pretty easy to calculate. You check the altitude at the starting point and reset the odometer trip meter. You climb a certain distance and divide the change in altitude by the miles you've traveled. This is not technically the grade, but for normal roads that aren't very steep, it ends up being pretty close because the horizontal distance and the length of the actual road are nearly the same.
you learn something new everyday :cool:
The EXACT grade
 

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Inbred Homebrewer
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george_da_trog said:
Hell, it's only .3 miles long.. We've got a little local section that floats between 14% and up to 18% for a good mile. Then there is the county line climb which averages 12% for 2 miles.

george
Actually, it's almost 2 miles long. (52.4 to 54.3, the Hawk Mountain sign at 52.7 is not at the top.) Never said it was the biggest or toughest climb in the world, just one of the steeper ones around here.
 

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George, I don't think you are right about the degrees thing...

george_da_trog said:
What's really fun is when you convert %grade to degrees. So a 10% grade, which hurts, is actually 4.5 degrees. How many times have you heard someone talking about a 45 degree slope they just climbed... 45 degrees = 100% grade.

george
I may eat my words, but a flat road has zero degrees of incline, and a road that went straight up to the sky would have a 90 degree incline. So a 45 degree climb is a 50% grade (50% of the possible maximum of 90 degrees).

And as far as Noelg's explanation above, grade has to do with whether the surface has been smoothed out mechanically, as in "has that road been graded recently?"

John W.
 

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pedaller
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PJ - I hope you're hungry :)

Check out the link on my last post.

You are talking about the ANGLE and that is actually the arc tangent of the rise/run.

Now we're getting into trigonometry and that's why they invented GRADE to begin with - to avoid that. :cool:
 

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Rolling
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Spring Fling teaser

george_da_trog said:
...How many times have you heard someone talking about a 45 degree slope they just climbed... 45 degrees = 100% grade.

george
No kidding! I know very few ppl who can even ride down 100% grade and no one who can ride up it. For those who have been to moab, every single part of the main slickrock trail is less than 100% (45 degrees) and most are less that 30 deg. Gotta go to other sections to approach 100%..John, the way grade is defined you can have over 100% grade...all the way to infinite percent grade (pure vertical).

 

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pedaller
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we're still not exactly right

george_da_trog said:
What's really fun is when you convert %grade to degrees. So a 10% grade, which hurts, is actually 4.5 degrees. How many times have you heard someone talking about a 45 degree slope they just climbed... 45 degrees = 100% grade.

george
a 10% grade is actually an angle of 5.71 degrees:

To calculate the angle of ascent when you know the percent grade, you simply take the arc tangent of the grade (the inverse of the tangent). So, if you have a 10% grade, you look up the arc tangent of 0.1 and find that the angle is 5.71 degrees.
GRADE
 

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Ride what you want!!
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Stick said:
Actually, it's almost 2 miles long. (52.4 to 54.3, the Hawk Mountain sign at 52.7 is not at the top.) Never said it was the biggest or toughest climb in the world, just one of the steeper ones around here.
I looked at it wrong... I still don't want to climb it.

george
 

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Medium?
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ShortCut in Henry Coe SP

(Hobbs Rd, from Middle Fork of Coyote Creek up to Blue Ridge) climbs 1300' in 1.3 miles, so it averages 20%. Bear Mountain Road has a section that climbs over 1000' in under a mile, so it's about the same. I will never be able to ride up either. I heard that Fourarm Crank has climbed Bear Mtn Rd.

Actual elevation is 900' less than this graph shows
 

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beer thief
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The Mt Washington, NH Auto Road is 7.6 miles long, has an average grade of 12% with extended sections of 18% and the last 50 yards is 22%!

Tyler Hamilton shattered the record with a stunning climb of 51 minutes, 56 seconds on Saturday, Aug. 23, 1997. Tom Danielson of Durango, Colorado and East Lyme, Conn holds the current record at 49:24, set in 2002.

Genevieve Jeanson of Lachine, Quebec holds the women's record of 54:02, also set in 2002.

The preceding was a copy & paste from Google. Riding down the Auto Road (prohibited) is a blast, if you get permission from the right people.
 

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For practice climb this

Towsley Canyon loop near Magic Mountain. Burned over by last year's fires the views are stark and unobstructed. The loop is 5.24 miles with an average grade of 14%. At least one section is 29%. Look carefully in the photos for a rider on a Pink SS! (insert evil laughter here).
 

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It's better to learn something new than be right!

Noelg said:
you learn something new everyday :cool:

Having gotten such a RISE out of Noel, I hated to RUN, but the lure of 50-Year Trail took me on a TANGENT down a steep mountain GRADE that couldn't be resisted. When I got home I decided to come at this issue from another ANGLE, and I went to the website Noel had linked us to. I nearly ARCED :mad: when I realized how wrong I had been about this whole matter.

So, with apologies to George, I broiled my previous words and ate them for dinner before getting back to the forum. I am more than willing to admit that I learned something new here today.

The last quarter mile of the road up into Madera Canyon south of Tucson must be in excess of a 15% grade. I don't know of anything steeper here abouts.

John W. :cool:
 
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