Difficulty Index?

[RickZ]

I seem to remember seeing some info about what the Difficulty Index #s mean/relate to for each ride but can't seem to find it anywhere.
Can you help?
Thanks, RickZ

[admin]

If you click on any particular video in our web store you will see some details including difficulty index. Here is the example: https://veloreality.com/product/marmotte-france-part-4/ for Marmotte Part 4. It has the index of 62.
You can also see that in the software for the videos you bought (it is called "Score" in there). You might have to move splitter to extend video list area to the right so all the info fits.

[SparkyCanada]

I seem to remember seeing some info about what the Difficulty Index #s mean/relate to for each ride but can't seem to find it anywhere.
Can you help?
Thanks, RickZ

Hi there.

New to indoor riding with videos.

I too would like to know what the "Difficulty Index" means/relates to.

Thanks,

SparkyCanada

[admin]

We use one of the common algorithms for estimating difficulty of the ride,
I think this one: http://www.climbbybike.com/climb_difficulty.asp
How it translates to one's personal feeling I have no idea
my guess it would be highly individual.

[HHRoadtrip]

After you have ridden once or twice, you will likely conclude that the "difficulty" of any course is of only minor consequence. For me, on an outdoor (real) route, a course is difficult only if I run out of gears. With just minimal use of VeloR's "grade reduction", I don't run out of gears. As a result, the difficulty of a course is solely a function of how hard I choose to pedal.

[SparkyCanada]

Thanks for all the reply's everyone.

I guess I'm just looking for a guide.

Something that lets me know the difficulty index suitable for:

• Beginners is X-> Y
  Intermediate is X->Y
  Senior/Pro is X->Y

I would use these references when choosing rides to purchase...

Thanks,

SparkyCanada

[admin]

Thanks for all the reply's everyone.

I guess I'm just looking for a guide.

Something that lets me know the difficulty index suitable for:

• Beginners is X-> Y
  Intermediate is X->Y
  Senior/Pro is X->Y

I would use these references when choosing rides to purchase...

Thanks,

SparkyCanada

Grade reduction setting in the software is roughly equivalent to having infinite virtual gearing. And having that you can always choose the settings that suit your condition. So as HHRoadrtip already pointed out this index when on trainer means zilch. The only thing that matters is at what percentage of your threshold power you will ride and for how long. For example riding at your FTP will by definition leave you nearly dead after one hour disregarding whether you did it on flat or on a steep hill.

Personally when I ride I do not go/watch for distance/road grade. I just count wasted energy (Kilo Joules). I know if I spent 1000 I can have that nice dinner without gaining weight

[Mighty Malc]

Thanks for the link to the climbbybike difficulty index formula.

I have replicated their calculation in Excel and agree with their results for each of Stelvio, Alpe d'Huez and Mortirolo (the only ones I have tested out). Good.

The Velo Reality difficulty index is apparently half of the climbbybike difficulty index for Stelvio and Alpe d'Huez. Good - happy if VR halves all climbbybike values because it is only a relative comparison that matters.

climbbybike has Difficulty Index 178 for the Mortirolo (which I agree with) and half of this is 89. But Velo Reality has Difficulty Index 134 for the Mortirolo!

The maximum gradient on the Mortirolo is usually given as 18%.
Even if I create a synthetic profile for the Mortirolo with as much as possible at gradient 18% while keeping total ascent correct (a monster of a climb, far worse than the real Mortirolo climb) I can only get to a VR value of 131 not 134. So I find it impossible to believe VR is genuinely getting a bigger value by using shorter sections to model the climb more accurately (than the 0.5 km sections used on climbbybike = same as those given in the book 'Mountain High').

I know this Difficulty Index stuff is not that important compared to cycling the climbs, but I am wondering if there is a mistake in the VR published Difficulty Index for the Mortirolo?

[admin]

...I know this Difficulty Index stuff is not that important compared to cycling the climbs, but I am wondering if there is a mistake in the VR published Difficulty Index for the Mortirolo?...

This is snip directly from our code so you can see the formula:

iDifficulty := (fAscend*100/fAscendDistance)*2+fAscend*fAscend/fDistance;
if fMaxHeight>1000 then
iDifficulty := iDifficulty + (fMaxHeight-1000)/1000;

I do not see any bugs in here. However there is a difference between our formula and theirs in that they use plain distance (assuming that it is all just straight single climb) meanwhile we are using only ascend value in order to cover cases like this:

On top of that we actually rode the thing and used barometric altimeter to record and calculate road grades based on elevation meanwhile they most likely use some Google like elevation data that can add another difference. Take a look for example at picture/coloring of our profile in the software versus what they have on Climbbybike and you might see quite a bit of difference. Also we might have different algorithms to determine what the ascend is.

Anyways we have the formula and it is here. We can't really to conform to some standard as there is none that would cover generic case. Also it is largely meaningless on a trainer anyways unless your trainer can REALLY simulate all physics of a steep climb and you do not use any software scaling of grade/virtual gearing/whatever. Having tried many trainers I know of only one that can do this kind of simulation.

[Mighty Malc]

Thanks for the code snippet - it all makes sense now.

My Excel spreadsheet using your formula gives the same values as on the VR site for 4 climbs I input, including the Mortirolo. Excellent. Now happy that your Mortirolo value was not a mistake.

The climbbybike formula is just different from your formula so gives different difficulty index. And it was pure coincidence that halving their value for 2 climbs gave the same value as your difficulty index.

Very much appreciate you publishing your formula so promptly in reply to my question.

Now I can go back to cycling instead of examining formulas