Gradients?

I've used bikehike.co.uk - Home to work out gradients on some of the roads I travel on. What units are they giving the gradients in? It doesn't say!

And how could I convert them to degrees?

Not sure about units of measurement, but there's a useful 'at-a-glance' comparison chart below, about half way down the page.

Gradient, Slope, Grade, Pitch, Rise Over Run Ratio Calculator

Remember the divide into 100 rule. To turn one-in-something to degrees of gradient, divide 100 by the something. To turn slope percentage into one-in-something, divide 100 by the percentage.. For example:

I in 8, divide 100 by 8 and you have 12.5, therefore it's roughly a 12% hill.

Conversely:

!2% hill, divide 100 by the 12 and the result is just over 8, therefore it's a 1 in 8 hill.

I might need to find another website to display gradients, still can't work out what the units are on BikeHike, but it isn't 'one-in-something' degrees, or percent. Therefore I can't convert it to anything!

If I could find a road in the UK with the gradient stated, I would run it through the course creator and see what it says.

You can work it out ok in BikeHike, I've just done it on a sample hill. Using Titsey Hill in Kent, I marked a known downslope as a route. Then on the data at the right it showed total descent 263 feet. With "Elevation" chosen as the graph display option, the base line showed my route as 0.5 miles which is 2640 feet.

So dividing 2640 by that descent of 263 feet gives me 10.04, therefore 1-in-10 or 10%.

If a route you mark down a hill comes out an in-between length, just adjust it to end up as a marked distance on the graph in units of 0.1 of a mile, or measure the difference carefully on the baseline to work out the number of feet.

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Edited May 26, 201213 yr by flecc

I haven't had any luck with bikehut.

I tried a number of know flat spots such as the roads over the top of dams. Showed a dip of 30-70 feet in the middle of all of them.

I haven't had any luck with bikehut.

I tried a number of know flat spots such as the roads over the top of dams. Showed a dip of 30-70 feet in the middle of all of them.

Take a break from it all! Go to the Netherlands for a week!

I haven't had any luck with bikehut.

I tried a number of know flat spots such as the roads over the top of dams. Showed a dip of 30-70 feet in the middle of all of them.

Sanoodi used to produce a similar problem. In that case I found it was the way it dealt with the contour spacings, but it seems to me there is an intrinsic problem with getting consistent gradient accuracy in all such programs. It's why I measure gradients physically.

Take a break from it all! Go to the Netherlands for a week!

If I come to a nasty hill I turn either left or right and avoid it.....

If I come to a nasty hill I turn either left or right and avoid it.....

I don't DO hills!

Answering Flecc,

I suppose the problem is that over a short distance, the contour lines indicate the land and not anything built upon it.

Even so, bikehut suggests a big dip in a hill close to my home which is in fact a steady uphill gradient.

Answering Flecc,

I suppose the problem is that over a short distance, the contour lines indicate the land and not anything built upon it.

Even so, bikehut suggests a big dip in a hill close to my home which is in fact a steady uphill gradient.

In Sanoodi's case when in it's original form, it wasn't buildings but the way it appeared to operate from a base point. If there weren't sufficient contour lines over the measured distance to assess the gradient from, sudden gradient changes occurred in the middle as you've found, and the start and finish of gradients were often wrong too.

In July 2007 I published a post with graphs on here to show the causes of the problem, but unfortunately earlier posts have had all the images removed by this new website host. However, the text of that original post explains, so here's the link to it.

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Edited June 4, 201213 yr by flecc

Thanks Flecc.

Seems the only real way is to use a clinometer. I have made a rather crude one using a spirit level.