Hill Steepness Rating

wolf1728

There was a thread discussing steepness of grade, gradient, etc here:
http://www.bikeradar.com/forums/viewtop ... t=12552936

It also mentioned that my website had a slope calculator but it is better for algebra than for road grades. However, that led me to work on a calculator for computing road grades, angles, gradients, etc and it is located here:
www.1728.com/gradient.htm

Basically my question is if the tangent function is used to calculate grade angle, etc, does the sine function have its own particular uses? I mention this because Wikipedia thought it worth mentioning both methods when they discussed road gradient.
http://en.wikipedia.org/wiki/Grade_%28slope%29

Scroll down to the table that shows Degrees Tangent and sine and you'll see what I mean.

synchronicity

Sine would come in handy if you've just measured the hypotenuse of a slope using the bike computer & you know the altitude difference from an altimeter...

On really steep slopes, you have to take this into account.

wolf1728

Any suggestions for websites or links that describe road grades and their difficulty when cycling?

bahzob

I use http://www.climbbybike.com/

wolf1728

Actually, I was thinking in more general terms rather than specific locations.

For example:
1% - easy climb
2% - Difficult after 1 hour
10% - almost everyone has to get off and walk.

That sort of thing.
Any websites like that?

inaperfectworld

well it's both length as well as steepness. however in my opinion 20%+ means you are going 3.5-4mph and a bump in the road is to be avoided because of the extra effort required and would be walking for anyone who is not a committed cyclist.. anything over 10% is steep, 5-10% requires a bit of a push. 1-4% just annoying because it's not hard but is slowing you up .

inaperfectworld

actually forgot to add that it is very hard to determine precisely gradients as they are varying on an ascent ( very few hills are of constant gradient throughout) it depends on your measuring points: 1 in 7 over a 1/2 mile can conceal a 1 in 4, and your 1 in 7 over 1/2 mile could be 1 in 13 over a mile

Monty Dog

1-4% = false flat
5-8% = steady drag - generally a seated climb / steady rhythm
9-12% = steady climb - might have to think about getting out the saddle
13-16% = getting steep
17-20% = steep - gear choice getting critical, care to prevent wheelspin in the wet
21%+ = very steep - good technique essential
30%+ = ridiculously steep - just getting up is the aim!

roger_merriman

inaperfectworld wrote:

actually forgot to add that it is very hard to determine precisely gradients as they are varying on an ascent ( very few hills are of constant gradient throughout) it depends on your measuring points: 1 in 7 over a 1/2 mile can conceal a 1 in 4, and your 1 in 7 over 1/2 mile could be 1 in 13 over a mile

quite, the hill nr my folks place is 20% but takes a while to get going and thus peaks at around 35%

wolf1728

Well, I finished the calculator and the text. (Yes, I researched grade, gradient, slope, angle, tangent, sine, pitch of a roof and so on).
Anyway, it is located here: http://www.1728.com/gradient.htm
and I think it should be suitable for just about anybody.
Slope can be expressed as a ratio, an angle or a grade. If you know 1 of these, the calculator will compute the other two.
Thanks to everybody for the help.

parky53

roger merriman wrote:

quite, the hill nr my folks place is 20% but takes a while to get going and thus peaks at around 35%

Which hill is this then? At 35% surely it must be quite well known?

KEITH

Nuggs

Monty Dog wrote:

1-4% = false flat
5-8% = steady drag - generally a seated climb / steady rhythm
9-12% = steady climb - might have to think about getting out the saddle
13-16% = getting steep
17-20% = steep - gear choice getting critical, care to prevent wheelspin in the wet
21%+ = very steep - good technique essential
30%+ = ridiculously steep - just getting up is the aim!

I think this is more accurate for me:
1-4% = false flat
5-8% = Ventoux - secretly hope for a p*ncture so death can be avoided
9-12% = Marmotte - going so slowly that a clipless fall is almost inevitable within the first 5 minutes
13-16% = Only achievable by car
17-20% = Only achievable by cablecar
21%+ = Only achievable by helicopter
30%+ = Sheer face, sheer impossibility

Anonymous

For me:

1-4% = false flat
5-8% = steady drag - generally a seated climb / steady rhythm
9-12% = Out of the saddle, try and keep a rythm, proberbly going about 10mph
13-16% = getting steep
17-20% = steep - gear choice getting critical, care to prevent wheelspin in the wet
21%+ = very steep - good technique essential
30%+ = ridiculously steep - just getting up is the aim!

So pretty similar, hardly any changed to one of the guy above, I managed to get up a 33% climb, the speeds on that was about 1.5-4mph as it was like 20% then a short bit at 33% but was amazingly hard.

roger_merriman

parky53 wrote:

roger merriman wrote:

quite, the hill nr my folks place is 20% but takes a while to get going and thus peaks at around 35%

Which hill is this then? At 35% surely it must be quite well known?

KEITH

why? it's just a steep hill, which in a gorge is well to be expected, there are a number of hills that peak at the around the same ie just getting up is the aim, and thats with MTB low ratios...

Clydach Gorge is the place.

Anonymous

roger merriman wrote:

parky53 wrote:

roger merriman wrote:

quite, the hill nr my folks place is 20% but takes a while to get going and thus peaks at around 35%

Which hill is this then? At 35% surely it must be quite well known?

KEITH

why? it's just a steep hill, which in a gorge is well to be expected, there are a number of hills that peak at the around the same ie just getting up is the aim, and thats with MTB low ratios...

Clydach Gorge is the place.

Is it a 35% hill on road? If so then it proberbly should be names, anything that steep is named.

SCR Pedro

Hey there,

Here is the point of view from a student with far too much spare time...

1-4% = False Flat. No point in spending too much energy trying to counteract it
5-8% = Steady Gradient Might consider dropping down from the big ring. If I'm into a headwind, I'd also start muttering under my breath
9-12% = A worthwhile hill. Yes, this is more like it. Drop down a few gears and try to get a good cadence going. Get into a mental zone. Unzip the jersey and try to look cool for passing cars.
13-16% = Picking up now. Just keep the rythmn going. If into a headwind, I'd be swearing. Just some blasphemy for now. Might consider standing, but not likely.
17-20% = Getting tough. Usually a short climb for this gradient. Just stand and suffer through it. Not enough spare breath for swearing now.
21-25% = Brutal. I will get up it, just not very fast. Rythmn and mental zones are right out the window by this point.
25% + = Where? I hope nobody is watching. Swear generously. Usually a string of slurs in several languages and possibly some words that never previously existed.

Cheers
Pedro

wolf1728

I have worked some more on my website page and have drawn a rather interesting chart (or graph). It has various road grades, ratios and 5, 10 15 and 20 degree angles are drawn.
www.1728.com/gradient.htm

Why didn't I show road grades steeper than 20 degrees? There is no road anywhere in the world that has a slope of 20 degrees or greater. I guess it's pretty much agreed that Baldwin Street in New Zealand holds the record for steepness which still falls a bit shy of 20 degrees. It's funny to think of road grades in terms of degrees isn't it? Climbing a tough hill you might be thinking "wow this must be a 40 degree tilt" but chances are it is more like 10 degrees (if that).

synchronicity

Isn't Baldwin over 20° at the upper section?

There are even parts of Monroy St here in Tenerife which are greater than 20°. Get out your protractor!! :twisted: :twisted: :twisted:


There's an interesting blog post written below. Many other steep streets have been added and there are ones mentioned in poorer countries that are not well documented.
http://deputy-dog.com/2007/09/18/the-st ... the-world/

FJS

synchronicity wrote:

There's an interesting blog post written below. Many other steep streets have been added and there are ones mentioned in poorer countries that are not well documented.
http://deputy-dog.com/2007/09/18/the-st ... the-world/

Great link, that!
I thought this was pretty impressive: http://www.climbbybike.com/climb.asp?Co ... ainID=3597
apparently 45 % (what degree angle would that be?), and that on a 7.5K/ 17% average climb.....

wolf1728

A 45% grade would be an angle of 24.228 degrees.
(Just visit my site and use the calculator).

bianchi77

I'm sure that gradient is tangent alpha where tangent is equal to vertical / horizontal

wolf1728

Bianchi77
What do you mean by tangent alpha?
You mentioned that it would be equal to vertical / horizontal but isn't that what tangent is anyway? (tangent = opposite / adjacent)