Total Climb or % - how do you calculate it?

[marinyork]

In anycase on topological maps it's a lot more complicated as you have partial derivatives in the directional derivative. Even the errors on these can be non-trivial. Models are how they are because it would take a lot more programming effort or computer resources to improve them and it's just not worth it.

 

[RedBike]

One of the reason mapping programs are inaccurate is because of the number of points they take.

For example if they only take the height at say 100 points along the route then on a 100mile route these points would be a mile apart. Two points a mile apart could easily be at the same height, yet there could be a wopping big hill inbetween them which wouldn't be counted. The longer the route the more inaccurate most online mapping software becomes.

Another reason is they often don't take into account man made heights; for example bridges, tunnels etc. Anywhere where the road has been highered or lowered.

 

[marinyork]

It's a lot more profound than that. Even if you had an infinite number of points you could still have errors.

 

[garrilla]

so we're back to if its hurting and its slow its very steep?

 

[summerdays]

For me its steep - anyway I put it into that web site and came up with the following:
(3 legs of the journey)
Leg 1 Leg2 Leg 3
Total Ascent 509 948 466
Total Decent 705 896 463

Does the total ascent equal the combination of each leg yes? so 1923 and descent 2064?

If I end up back at the beginning how come I have descended an extra 140 ft?

And I toggled a graph of gradient and ended up with this:

for one of the legs of the journey. For me all i can say is I'm tired

 

[marinyork]

How long is the journey in total? It all adds up.

 

[summerdays]

The total journey was 5.93 + 7.18 + 3.63 = 16.74 miles apparently

 

[zacklaws]

There is a website with a dedicated program for calculating gradient wherby you just click on the points of a feature you want to check and it will give you the gradient broken down into little segments, colour coded too .

As I am at work at the moment I cannot give a link to it but will first opportunity

 

[zacklaws]

As promised, here's a link to a site that will do a profile. As a rule though I treat it with a pinch of salt as I sometimes think it gets it wrong, but there again it might be right and I'm fitter than I think or unfitter depending on what grade it comes up with.

http://www.heywhatsthat.com/profiler.html

 

[summerdays]

That's a useful site - I have just tried it on all the hills that I hate locally and on each case there is a section which according to that site is above 10%. At least I can use that site as an excuse as to why I don't like a particular hill.

 

[jimboalee]

that is exactly why the mapping programmes underestimate incline

you have done elevation / distance travelled, but distance travelled is not the same as the true horizontal distance, and to calculate that you must use the theorem

The gradient is a/b. The OP only has a and c

If a = 200, and b is 2640, the difference between b and c ( as far as I am concerned ) is a gnat's cock.

 

[garrilla]

If a = 200, and b is 2640, the difference between b and c ( as far as I am concerned ) is a gnat's cock.

I did kind of accept that a few posts back... And using PT did not help me but just reinforced this small difference.

Yet the use of topo data on some longer ascents it would make more of a difference. For example, the climb out of Glossop to the top of Snake Pass is 1080 feet - if you use the Glossop club starting point - its about 3.2miles distance travelled and about 2.8miles horizontal distance. The former gives you a grade of 6% the latter of 7%. Its classed as a 7% grade.

So the point I was trying to make was valid (probably) but the way I chose to make it leaves much to be desired

 

[jimboalee]

I did kind of accept that a few posts back... And using PT did not help me but just reinforced this small difference.

Yet the use of topo data on some longer ascents it would make more of a difference. For example, the climb out of Glossop to the top of Snake Pass is 1080 feet - if you use the Glossop club starting point - its about 3.2miles distance travelled and about 2.8miles horizontal distance. The former gives you a grade of 6% the latter of 7%. Its classed as a 7% grade.

So the point I was trying to make was valid (probably) but the way I chose to make it leaves much to be desired

I've been thinking about gradient calc methodology.

My thoughts....
Grab an OS map and choose two towns. They have Grid references. Take a ruler and painstakinkly measure the road distance between them. This IS the distance, according to cartographers.
If the towns were on two different continents, taking a ruler and measuring the road distance would be a waste of time because first you need to plot a Great Circle straight line to approximately follow.

Even in the same country, eg USA, the distance would need to be measured by Great Circle. This is the way digital mapping calcs the straight line distance.
Elevation doesn't come into it. If the route between the two towns is generally uphill, that's tough shoot.

Go back to the OS map. Split the route between the towns into little bits, terminating at contour lines.
The distance that a cycle computer would record ( rotations of the wheel ) is the result of Pythagoras' theory, and the slope a function of the Tangent of the vertical difference divided by the horizontal distance measured with the ruler. SOH, CAH, TOA as I learned at school.

In the old days, we had an OS map, a little wheely thing for measuring the distance and a cyclimeter to record the 'overall' distance. We knew they would not agree and accepted it. Early Audaxers would check the OS map to identify any BIG hills and do a quick estimation of their severity.

OS put a little black chevron, or chevrons ( pointing downhill ) on the map to indicate hills steeper than 14% and 20%. These are the ones to be worried about.

A hill without a chevron should be climbable with the OEM gears on your bike.

 

[garrilla]

Jimbo, thanks for digressing with me.

Like you I guess, I treat hills as "f*&^%ng hell that is going to kill me" > "sh*t its killing me" and "whoooooooooo, I survived, now can I stay on while I descend like maniac"

 

[wesa]

A hill without a chevron should be climbable with the OEM gears on your bike.

I feel better now, the only hill that has recently beaten me has double chevrons (Round Hill out of Winchcombe - I have another appointment with it soon!). I am also pleased to see that a number of hills that I have conquered (albeit slowly) are shown with a single chevron.