Monday, August 13, 2012

How To Calculate the Elevation Grade Of Your Uphill Walk Or Cycle

You ride, walk, or hike a hill, and it felt like your strongest uphill effort ever. You want to know, for posterity, the average elevation grade of that climb. For us stat geeks, that's a percent elevation grade, such as "10 percent."

You might recall from Tour De France broadcasts the breathless coverage of a hard climbing stage – "this part of the climb averages 12 percent or more!!" These climbs are generally rated by their average elevation grade and length. The famous Alpe D'Huez climb in the French Alps, for example, is around 8.5 miles long with an average grade of almost 8 percent.

In short, a road with an eight percent grade ascends in elevation eight feet for every 100 feet in length. Beyond having a watch that produces this statistic for you (and my old Garmin watch will do that, after you consult a chart), how do you figure out the average elevation grade? It's a fairly easy equation for us do-it-yourselfers, using either feet or meters, for example.

Increase in elevation for the climb / Total distance of climb * 100

Last night, I took a very fine evening ride on my mountainbike in Vermont, USA. It included a nice climb which I've measured by hiking with Endomondo. The climb was 1.14 miles (about 6,019 feet) in length, and rose 580 feet in elevation. So:

580 / 6019 = 0.0963 * 100, which = 9.6 percent

My mile or so ride had an elevation grade of about 9.6 percent. For every thousand feet of length it rose about 96 feet in elevation or steepness – so imagine starting at one end of a football field on a bike, but the other end of the field is tilted up about 29 feet. That's about how steep the road was.

Anything of around 10 percent is pretty hard steepness on a bike (easier for walkers or hikers), and requires a small chain ring and a low gear on the bike to negotiate for any length (for us mere mortals).

A long ride, 10 to 20 miles long, with a 6 percent average grade, is very strenuous, and requires a low gear and lots of water. On rare occasions I train on a climb that is 3.6 miles long (6 kilometers) with a grade of six percent, and that's a confidence builder, because it's climbing but not that hard.

Have any bike or run climbing stories to share?

1 comment:

  1. I believe you, but mathematically, this means a 100% gain is 45 degrees. So it's possible to have a gain >100%?