When does an incline become a hill ?

[exbfb]

Me = beginner.

There are a few bits on my commute and on my favourite loop around where I live that include what I might call hills.

To me they feel like hills anyway

Output from my Nokia 5800 and Google earth says about 10% or 1 in 10.

Is that a hill or am I more of a beginner than I think I am ?

I should probably forget about ti and just get on with it, but I can't help being an anorak.

 

[coffeejo]

I grew up in west Wales so my perception of what is and isn't a hill is somewhat skewed

 

[the_mikey]

Well, 10% sounds like a hill to me....

 

[raindog]

10% is a decent climb - I'd say anything from 4 or 5% upwards is a hill.

 

[Paul_L]

Very much depends on the individual. For me, i'm perfectly happy with anything upto 5% to be classed as an incline. Above this, it's a hill.

Worth noting though that a long tough climb might have an average from the bottom to the peak of between 4 and 5 %, so for the purposes of your question, i think we're talking instantaneous percentages not those of an overall climb.

 

[The_Wheelhouse]

10% or 1 in 10

FYI 1 in 10 is not 10% It's basic trig for every ten units along you go one unit up, therefore tanø=1/10
or ø = 5.7°

 

[exbfb]

FYI 1 in 10 is not 10% It's basic trig for every ten units along you go one unit up, therefore tanø=1/10
or ø = 5.7°

My apologies.

I have learnt from something from all of your answers.
Being a wimp, I'll wait untill the rain goes off and try some of this again

 

[david k]

1 in 10 is still 10% isnt it?

5 in 10 is 50% would that then be 45 degrees being half of 90? help me here

 

[The_Wheelhouse]

My apologies.

I have learnt from something from all of your answers.
Being a wimp, I'll wait untill the rain goes off and try some of this again

1 in 10 is still 10% isnt it?

5 in 10 is 50% would that then be 45 degrees being half of 90? help me here

Opps I guess it is time for me to apologise I totally mis-read that and you are correct in saying that 1 in 10 is 10%

 

[psmiffy]

1 in 10 is still 10% isnt it?

5 in 10 is 50% would that then be 45 degrees being half of 90? help me here

1:10 = 5.7° = 10%

5:10 = 1:2 = 26.6° = 50%

1:1 = 45° =100%

 

[The_Wheelhouse]

Sorry to hijack this thread but thinking about it a bit more 5 in 10 is 50% but 5 in 10 is not 45º as tanø= 5/10 so ø=26.6º so i guess it is totally dependant on what you take as 100% in this case 45º is 100% as 1 in 1 would mean that the gradient of the slope is tanø= 1

 

[cyberknight]

Its a hill when i need to use the smaller chainring

 

[ColinJ]

The gradients of roads should really be measured by the vertical height gain divided by the horizontal distance travelled. That slope would be the tangent of the angle between the road and the horizontal.

In practice it is hard to measure the horizontal distance travelled without burrowing into the hillside so we normally measure along the road instead. The slope is then approximated as height gain divided by the length of road or the Sine of the angle between the road and the horizontal.

For moderate hills the difference is tiny. For incredibly steep hills it wouldn't be.

The '5 in 10' example would be significantly out. By Pythagoras' Theorem, if the hypoteneuse (road length) is 10, and the height gain is 5, then the horizontal distance travelled is (10[sup]2[/sup] - 5[sup]2[/sup])[sup]-2 [/sup]=[sup] [/sup](100 - 25)[sup]-2[/sup] = 75[sup]-2[/sup] = 8.66. That is the slope would actually be 5 in 8.66 not 5 in 10 (1 in 1.73, not 1 in 2). That's a big difference. Roads that steep do not exist because we wouldn't be able to use them!

A more practical example - 1 in 5 or 20% should really be 1 in 4.90 or 20.41%.

It's only of academic interest really, isn't it? if you are grovelling up a '1 in 5' do you really care that it should be called a '1 in 4.90'?

 

[numbnuts]

When you get to my age every incline is a hill and every hill is a mountain but I'm dammed if I'm getting off and walking

 

[gaz]

Shouldn't it be based on how long it is? I probably have a few 1 in 10's on my commute but they are less than 100m long so I just sprint up them. Hardly a hill.