Gradients
rubertoe
Posts: 3,994
What with the "hills that make you get of and Walk" thread, there is a lot of talk about gradients.
I am confused?
Can someone explain to me in lay terms what is meant by a gradient described as a % (i.e 10%) and what is meant by a gradient described as a fraction (i.e 1/3).
And what it means in real terms? if say traveling over a 1000m (or 1 Km/mile) or whatever on a 10% climb how many meters above sea level would I end up at if I started at sea level...
I am confused?
Can someone explain to me in lay terms what is meant by a gradient described as a % (i.e 10%) and what is meant by a gradient described as a fraction (i.e 1/3).
And what it means in real terms? if say traveling over a 1000m (or 1 Km/mile) or whatever on a 10% climb how many meters above sea level would I end up at if I started at sea level...
"If you always do what you've always done, you'll always get what you've always got."
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A 1-in-10 gradient (aka 10%) means that for every 10 metres you go horizontally, you go up 1.
1-in-4 (25%) means 1 metre vertical for every 4 metres horizontal.
More generally, a 1-in-n gradient (100/n %) means you climb 1 metre for every n metres horizontal.Pannier, 120rpm.0 -
This might help. The Y and X columns are effectively 1 in X with the equivalent percentage to the right.
So you'd go up 100 meters in your 1000 m travelled horizontally.Faster than a tent.......0 -
You know how fractions work right? 1/3 = 33.333333%What do you mean you think 64cm is a big frame?0
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cyclingprop wrote:You know how fractions work right? 1/3 = 33.333333%
I have a first degree in Engineering. Ergo I understand gradients. I have no qualification in gobbledegook. Ergo I do not understand Rolf's message.
For Rubertoe, I think TGOTB explains it neatly.0 -
vermin wrote:cyclingprop wrote:You know how fractions work right? 1/3 = 33.333333%
I have a first degree in Engineering. Ergo I understand gradients. I have no qualification in gobbledegook. Ergo I do not understand Rolf's message.
For Rubertoe, I think TGOTB explains it neatly.
Gathers round to watch the engineering slap-fight.0 -
So 12% would be 12 vertical metres gained for every 100 horizontal metres travelled?"If you always do what you've always done, you'll always get what you've always got."
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Yes, by jove I think he's got it!FCN3: Titanium Qoroz.0
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rubertoe wrote:And what it means in real terms? if say traveling over a 1000m (or 1 Km/mile) or whatever on a 10% climb how many meters above sea level would I end up at if I started at sea level...
Expressing gradient as a percentage is much more accurate and it is easier to work out how much you've climbed.
From sea level, if you travel 1000m horizontally on a 10% climb, you will end up 100m above sea level (100 = 10% of 1000m). A 15% gradient would mean a 150m climb etc.
The fractional description of inclines is a bit rubbish. The difference between 1 in 4 and 1 in 3 might not seem much in terms of raw numbers, but it means that the first one (1 in 4) is a 25% incline but the second one (1 in 3) is 33%.
When you get to lower numbers, 1 in 15 is just under 7% and 1 in 14 is just over 7%, so they give you less information.
I think the 1 in x roadsigns are (very slowly) being phased out.FCN 3: Raleigh Record Ace fixie-to be resurrected sometime in the future
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EKE_38BPM wrote:Expressing gradient as a percentage is much more accurate
I also have a degree in engineering. It may only be a third, but I did get good marks for pedantry...Pannier, 120rpm.0 -
I studied engineering (civil) but left before I got my degree. I lost marks for assuming too much knowledge in others (everyone knows what bentonite slurry is, right?FCN 3: Raleigh Record Ace fixie-to be resurrected sometime in the future
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EKE_38BPM wrote:I studied engineering (civil) but left before I got my degree. I lost marks for assuming too much knowledge in others (everyone knows what bentonite slurry is, right?
Lol - I am actually writing about bentonite slurry at this very moment. Or rather, I am posting here to avoid the tedium of writing about bentonite slurry!0 -
vermin wrote:EKE_38BPM wrote:I studied engineering (civil) but left before I got my degree. I lost marks for assuming too much knowledge in others (everyone knows what bentonite slurry is, right?
Lol - I am actually writing about bentonite slurry at this very moment. Or rather, I am posting here to avoid the tedium of writing about bentonite slurry!FCN 3: Raleigh Record Ace fixie-to be resurrected sometime in the future
FCN 4: Planet X Schmaffenschmack 2- workhorse
FCN 9: B Twin Vitamin - winter commuter/loan bike for trainees
I'm hungry. I'm always hungry!0 -
rubertoe wrote:So 12% would be 12 vertical metres gained for every 100 horizontal metres travelled?
Yes, but please note this is slightly different to saying 12 vertical metres gained for every 100m travelled on the bike as the 100m is travelled horizontally.
For most gradients this can be more or less ignored: it means 12m climbed for every 100.7m travelled on the road for a 12%. Even at 30% you're doing 30m of ascent for 104.4m. Pedantry for the win!0 -
vermin wrote:cyclingprop wrote:You know how fractions work right? 1/3 = 33.333333%
I have a first degree in Engineering. Ergo I understand gradients. I have no qualification in gobbledegook. Ergo I do not understand Rolf's message.
For Rubertoe, I think TGOTB explains it neatly.
Well D'uh! I didn't put the link in. Do I have to do everything around here?!
http://www.engineeringtoolbox.com/slope-degrees-gradient-grade-d_1562.html
PS I've drilled holes - I know what bentonite is!Faster than a tent.......0 -
Sorry, but 12% is closer to one in eight, so 1 unit climbed for every 8.3 units of horizontal travel.
12% = 1 in ( 100/12 )
= 1 in 8.3333
J.Reduce your carbon footprint - ride a metal bike!0 -
EKE_38BPM wrote:Expressing gradient as a percentage is much more accurate and it is easier to work
The fractional description of inclines is a bit rubbish. .
sorry nearly spat my coffee out at this one, so excuse my descent into pedentry.
Neither is more or less accurate, its just a different way of expressing a number.
Its like saying kgs are more accurate than lbs, i.e complete nonsense.
if something is a genuine 1in3 then to say it is 33% is less accurate, as it is 33.33 (recurrring)%
and vice versa a genuine 9% slope is not 1 in 11 its 1 in 11.11111(recurring).
In steps of whole numbers and restricted to "1" in then %age is a finer scale at steep slopes but fractions is a finer scale once slope is less than 10%.
For the record i'm not an engineer.Bianchi Infinito CV
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Also confusing is that some gradient signs show the gradient at its steepest point. Theres a 17% one near me and the 17% is probably 2ft long - I still have to get off and walk though....and thats going downhillThe dissenter is every human being at those moments of his life when he resigns
momentarily from the herd and thinks for himself.0 -
I did Maths at Uni - I never claimed I could spell.Bianchi Infinito CV
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fat_tail wrote:rubertoe wrote:So 12% would be 12 vertical metres gained for every 100 horizontal metres travelled?
correct .. doesn't sound like much does it ?
No it doesn't and if you look at elevation on a map etc the hills don't look all that big. There's plenty where you are climbing on your bike or on foot and it feels like 1:1 but it's a very long way from it!0 -
t4tomo wrote:I did Maths at Uni - I never claimed I could spell.
Personally I did engineering - this means that not only can I not spell but I think pi is 3, but lets call it 10 to be on the safe side. Not sure why other engineers are being so accurate though, all an engineer needs is good enough not right.0 -
Cleat Eastwood wrote:Also confusing is that some gradient signs show the gradient at its steepest point. Theres a 17% one near me and the 17% is probably 2ft long - I still have to get off and walk though....and thats going downhill
Yes - the French do it better in the Alps. Markers every km that show the ave and max % gradient over the next km.
So you know when to throw the towel in and give up...0 -
Greg66 Tri v2.0 wrote:Cleat Eastwood wrote:Also confusing is that some gradient signs show the gradient at its steepest point. Theres a 17% one near me and the 17% is probably 2ft long - I still have to get off and walk though....and thats going downhill
Yes - the French do it better in the Alps. Markers every km that show the ave and max % gradient over the next km.
So you know when to throw the towel in and give up...
There are climbs longer than a km? :shock:0 -
Runtothehills wrote:t4tomo wrote:I did Maths at Uni - I never claimed I could spell.
Personally I did engineering - this means that not only can I not spell but I think pi is 3, but lets call it 10 to be on the safe side. Not sure why other engineers are being so accurate though, all an engineer needs is good enough not right.FCN 3: Raleigh Record Ace fixie-to be resurrected sometime in the future
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I'm hungry. I'm always hungry!0 -
t4tomo wrote:EKE_38BPM wrote:Expressing gradient as a percentage is much more accurate and it is easier to work
The fractional description of inclines is a bit rubbish. .
sorry nearly spat my coffee out at this one, so excuse my descent into pedentry.
Neither is more or less accurate, its just a different way of expressing a number.
Its like saying kgs are more accurate than lbs, i.e complete nonsense.
if something is a genuine 1in3 then to say it is 33% is less accurate, as it is 33.33 (recurrring)%
and vice versa a genuine 9% slope is not 1 in 11 its 1 in 11.11111(recurring).
In steps of whole numbers and restricted to "1" in then %age is a finer scale at steep slopes but fractions is a finer scale once slope is less than 10%.
For the record i'm not an engineer.
FWIW I'd rather we stuck with the 1 in n method - it's so much more meaningful and we all know that a 1 in 3 is chuffing steep and a 1 in 20 is an easy slope. It's also how we always did it until some oik decided that 1 in something is too difficult to understand so we have to do it a different way. We should make life awkward for thickies.0 -
Was brought up on 1 in 'n' but quite like nn% these days. I tend to view it as "This one will leave you 5% dead....with one it's 20%....but THIS one? You got funeral insurance?"
And with that, I'll slope off...0 -
Just remember n% down almost certainly means n% up on the other side.--
Chris
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