Sweeper59 wrote:To work out the gradient of a road, simply divide the 'rise' by 'the run' i.e vertical distance by the horizontal distance and multiply by 100 to get a percentage. A road that rises 20m in 200 is said to have a grade of 10% (or 1 in 10).
Sweeper, many people mistake the distance they ride up a hill as the run. However, as you point out:
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rise is the net vertical distance ascended.
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run is the net horizontal distance traveled.
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slope is the distance traveled as per the bike odometer and is equal to the hypotenuse of a right angle triangle.
For slopes under 10%, the slope and run are pretty much interchangeable as the error is small.
However, over that and the difference is significant.
gradient = rise /(slope^2-rise^2)^(1/2)
Around Brisbane :
Gower St, Taringa has 30% posted at the top.
Mayfield Ct, Highvale (Samford Valley) I have measured at 31%.
Mt Coot-tha (from Simpsons Road to ABC) is around 9.5%, with a steeper section for 200 metres before channel 10.