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:

rise is the net vertical distance ascended.

run is the net horizontal distance traveled.

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^2rise^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 Coottha (from Simpsons Road to ABC) is around 9.5%, with a steeper section for 200 metres before channel 10.