I wouldn't say that 8-10% is that steep

[TSN79]

My physics-teacher drew a parallel to cycling and said that hills that were round 8-10% steep were really tough to climb. What does this mean? Would 100% be vertical and 0% horizonatl? If so, I wouldn't say that 8-10% is that steep at all really...if it steepness was given in degrees I could see it better...

 

[Jelfish]

I'm not so sure that using a percent is standard in measuring steepness, but I would imagine that your teacher probably means what you think, with 0% being 0 degrees and 100% being 90 degrees. I agree that it doesn't seem particularly steep for a cyclist, but I suppose that depends on the physical fitness of your teacher

 

[brewnog]

Would 100% be vertical and 0% horizonatl?

No.

You'll often see gradients (especially on roads) as being given in terms of a ratio, ie 1 in 5, where for every 5 metres you go along, you'll go up 1 metre. (Mathematically, the gradient would be 1/5).

When you see a gradient expressed as a percentage, it's merely a different way of expressing this ratio, or fraction.

In this case, a 45 degree slope would be 100%, and the 10% slope which your teacher speaks of is a 'One in Ten' incline.

As an aside, in real life, gradients often look a lot worse than they really are. The steepest roads in the UK aren't much more severe than 1 in 4, and a 1 in 10 slope is indeed a bit of a slog!

 

[TSN79]

Wow, thanks. I just can't seem to think that a 1 in 10 incline could be considered that steep, but then again I'm not a cyclist...and I guess you would get tired after some time.

 

[James R]

The difficulty also depends on the total length of the slope. Try tackling a 1 in 10 slope for an hour or so, and see how you go. I think you'll find it fairly tough.

 

[jtbell]

I've climbed some 15% grades on a touring bike. Even without any baggage, I had to get in my lowest gear, stand up out of the saddle, and pull up on the handlebars in order to exert enough force on the pedals to keep moving.

 

[PerennialII]

I've climbed some 15% grades on a touring bike. Even without any baggage, I had to get in my lowest gear, stand up out of the saddle, and pull up on the handlebars in order to exert enough force on the pedals to keep moving.

... having similar fond memories. Overall using %-grades gives really steep slopes a "low percentage", a 10-15% slope certainly isn't gentle or doesn't look like it when you're starting your climb, so the measure is usually a bit distracting.