pelirary

I've seen a lot of posts in different threads where riders talk about hills and degree of incline. Other than seeing a road side sign indicating the degree of the hill, how does one know that the degree is? Is there a method? I know that a twenty degree hill would mean that for every hundred feet the road rises twenty feet. I'm not saying that the knowledge of the degree will make it any easier to climb the hill, I am just curious. My ratings of hills goes from "this isn't too bad" to "OMG, why did I pick this road?"

spelger

measure the rise and divide by the run. multiply by 100 to get percent grade. not degrees.

Leisesturm

That may well be true, however I have (and the o.p. too, obviously) seen inclines expressed in degrees. The o.p. question is not wrong, degrees are a valid way of expressing incline. I've never been that interested in the details but I just found this with not that much time invested.

Iride01 

Grade just sounds better and gives us a larger number to deal with for our egos!

A 10% grade that makes us struggle climbing is only 5.7°. Even a 20% grade that we feel gives us bragging rights is only 11.3° <grin>

The formulas for various ways to figure slope/grade by percentage or degrees are here......

https://www.engineeringtoolbox.com/s...de-d_1562.html

There is a calculator you can plug in rise and run 1 or 2 clicks scrolling down. And a angular representation that shows what it looks like with the degrees and percentage shown below it.

There is a table a little further below the calculator that you can download and print out if it helps you for whatever you are doing.

terrymorse 

Really? You have seen road signs showing the roadway grade in degrees, rather than percentages? I have never seen nor heard of such a thing.

It’s a big world, so I guess it’s possible somewhere. Where was this?

pelirary

Ah, interesting. So now I need to carry a protractor around with me to check the incline of a hill? :-)

Black wallnut 

20° slope is 36.4 feet rise over 100 foot run. 20% slope is 11.31°

pelirary

You are right. The signs I have seen are showing percent gradient, not degrees.

spelger

i've driven on a lot of roads and have never seen grade expressed in terms of degrees. all the ones i have seen are yellow triangular signs with a ridiculously steep mountain with a number followed by the percent sign. i'd be curious to see one in terms of degrees.

spelger

juse use your phone. assuming you have a smart phone. you can find simple apps that will spit out the incline in terms of degrees.

PeteHski

My Garmin tells me what the slope gradient is in real time. If I have a route loaded it also has any significant climbs listed with gradients and length etc.

DiabloScott

Roads are listed in percent grade because they are designed by engineers who are looking at flat maps with gradient lines on them, and the lines were mapped by surveyors. So they measure a length, and then they subtract the lower elevation line from the higher elevation line and get a percent grade. Also road construction manuals list maximum gradients for different types of roads, and those manuals are also written by engineers. Nobody is out there using protractors.

Most GPS computers will have a screen that shows current grade, but I think they use data rather than calculations. And if there's a Strava segment on your ride you can check it out there:



Here are some guidelines:
5% = maximum grade for an ADA bridge.
10% = a good climber can stay in the saddle
15% = a good climber can do it out of the saddle
20% = only the strongest climbers will be able to do it at all
25% = ridiculous grade used for exhibitions and contests
30% = almost nobody will make it up

staehpj1

Yes always percentage never degrees for cycling or roads and trails in general. For rivers and streams ww paddlers use feet per mile or meters per kilometer as the usual measure.

ofajen

It goes like this for me riding single speed:
5% = stay in the saddle
10% = knees will be happier if I stand
15% = couldn’t stay in the saddle if I tried
over 15% = this is a good time for a walk.

Otto

locolobo13 

I let Strava do it. You could possibly do it in google maps. Never worth it. No matter what uphill is hard!

terrymorse 

A single speed? Yikes! I can't imagine doing double digit climbs on a single speed. My low gear is 34/28, and it's just about right for me on steep grades.

I did some steep but short climbs yesterday where Garmin displayed 15%, and up to 20% in short bits. Wanting to work my legs, I stayed in the saddle while doing a tempo power, but my cadence dropped to 50 much of the time. It wasn't that difficult aerobically, but my legs were much happier when the grade fell to "only" 11%.

A little steep segment from yesterday:

• distance: 0.14 mi
• av. grade: 14.6%
• av. speed: 5.0 mph
• av. cadence: 50
• av. power: 3.72 W/kg

Mashing a 50 cadence isn't a wonderful feeling, but I've never felt that spinning like a hamster at those low speeds is very productive.

PeteHski

I prefer a 1:1 ratio on climbs that steep. There is no danger of spinning like a hamster unless you opt for mtb gearing or have a 6 W/kg FTP.

terrymorse 

Safe to say there's no chance of that happening. Not without some amazing medical breakthroughs (which I might consider).

downtube42

Best to not use degrees, lest we really feel like wimps.

One might think a 20% grade is approaching 45 degrees, but it's a pedestrian sounding 11.3 degrees.

We are gravity challenged.

steelbikeguy

back in the days before smart phones, I used a Sky Mounti inclinometer. It's basically a bubble level that gives an indication of the grade of the slope. Easy to use, doesn't require software or batteries, but does use up a bit of space on the (round) handlebar.

For instance, this indicates about a 9% grade....



The best measurements are achieved when stopped, but you can get decent readings when riding too.

Steve in Peoria

Carbonfiberboy 

Absolutely not. The pitch of a road is always expressed in percent, rise over run, never in degrees. Ever. Same in every country. Most folks think 10% is a fairly hard climb. Where I live, and it's a mountainous area, 6%-7% is about as steep as main roads get. Side roads though can be up to 20%. which is very steep indeed for a cyclist.

As to how we know, many if not most of us have a device on the bike which measures distance and elevation, does the math, and shows the percent of a climb on the screen as we ride up it. There are also occasional road signs which show percent, usually for the benefit of truckers on long descents.

On the other hand, backcountry skiers express slope angle in degrees to get some idea as to avalanche possibility. And we do carry little gadgets to measure slope angle.

Carbonfiberboy 

We have a 26X40 on our tandem and I use a 26X30 on my single now. Back in the day when I could really ride, it was a 30X25 .

rsbob 

Most people who know the percent grade use a bike computer that provides them with a constant readout. My first one was an Avocet (no longer made) which had a built in altimeter. There are plenty of bike computers with built in altimeters like my Garmin. Or strap on a bubble level, like above.

sch

I use ridewithgps to map out rides as do most of the ride leaders in my area (bike club discount) and have found it universally
understates slopes. On hills I know to be 10-12% ridewithgps never finds more than 6%. The overall elevation changes
are generally pretty close to others like Garmins, Wahoos and cell phone apps but the inclines are not.
My phone says my driveway is 24%, I can ride up it ok in 32/34 gearing, but it is only 30 yds or so.

terrymorse 

I don’t think the Avocet displayed grade. The early Garmin units didn’t. I used to do math in my head to get a rough idea of the grade, and the rate of ascent (VAM). Having these on the display is quite the luxury.