# Inclines in Tour de France

I'm watching Tour de France these days, and I hear people talking about mountain stages etc, and they often say that this and that road has an incline of let's say 10 %...what does that mean? How steep is that?!

I think they refer to the gradient, so, say, a slope of $$\frac{3}{4}$$ is 75% incline.

Kurdt
Staff Emeritus
Gold Member
A 10% incline would mean you increase in height 10cm for every meter you travel.

brewnog
Gold Member
Both correct; 100% is a 'one in one' incline, or 45 degrees. (1:8 is 12.5% etc).

Great, thx guys!

Have you ever seen a 100% incline ? It is really inclined
I mean, realize the following : with a 100% incline, you will not see the road until your distance to the beginning of the slope equal the height of your eyes. Even two meters from the beginning of the slope, it looks like there is no road at all. Quite scary.

Also, inclines are catogorized into 5 or so catgories. I believe the lower the number the harder the incline. Is this right?

Chi Meson
Homework Helper
And then "HC" is the hardest since it is "beyond categories."

BobG
Homework Helper
Technically, climbs are rated by category. The length, number, and steepness of inclines involved in a long climb all go into deciding which category the climb belongs in. A particularly long incline with no breaks could result in a climb being rated in a tougher category than one with several very steep, but short inclines.

would 200% be straight vertical then?

No, 200% incline would be a gradient of 2, corresponding to an angle of arctan(2), or about 63.4 degrees.

Vertical cannot be assigned a finite value here. It would be "infinitely steep" somehow.

Vertical is not an incline, the closest to it would be technically indefinite I suppose, or more realistically depend on the slope.

For all intents and purposes in cycling a slope beyond a certain gradient would be irrelevant as it would be impossible for anyone to even attempt to traverse it.

I'd imagine 200% doesn't even exist in cycling, as that would be absurd unless it was a BMX jump or a bump in the road.

Last edited:
DaveC426913
Gold Member
Have you ever seen a 100% incline ? It is really inclined
I mean, realize the following : with a 100% incline, you will not see the road until your distance to the beginning of the slope equal the height of your eyes. Even two meters from the beginning of the slope, it looks like there is no road at all. Quite scary.
Ah. Took me a while to visualize this.

You're talking about being at the top of the incline looking down.