thiccboy compares some boots

[kamtron]

Presumably a skier will flex their boot more than 10 degrees, but the skialper test isn't getting you into the range. As you say, the forces are roughly comparable at 10 degrees, but we aren't seeing how the boot performs in deep flexion.

[shitskier]

It looks like the skialper ski flex is showing very small flexes/forces compared to the other graph

The buckling closure paper measured to deeper flexes than skialper, but their torque at 10 degrees is well within the range of the boots that ski-alper tested. They were using an 80-flex Head Edge in that paper.

In the paper that developed these methods (Petrone, 2013 https://donsnotes.com/sports/ski-boot-stiffness.pdf), they test a 150-flex race boot (boot #1).
Interestingly, it looked less stiff than the Quattro. However, not sure if the methods are comparable. One indication that they may not be is that curves in the academic test have a positive second derivative (stiffer as they flex further), the boots in the ski alper test look more like slightly negative at first and then linear.

[shitskier]

Presumably a skier will flex their boot more than 10 degrees, but the skialper test isn't getting you into the range. As you say, the forces are roughly comparable at 10 degrees, but we aren't seeing how the boot performs in deep flexion.

The 2013 Petrone paper says -5 deg to 15 degree should cover the range of actual skiing. The buckle closure paper (Petrone 2014) saw a maximum shell-tibia angle at 10 degrees during slalom style carving.

[kamtron]

Huh I would've thought that more degrees of flex is normal but I'm wrong!

[onenerdykid]

We (Atomic) flex boots to 15° past their natural forward lean. This is a real world flex range. Only going to 10° doesn't show the real progressive ramp up that many boots have. It's leaving out part of the flex curve that people will encounter.

[XavierD]

We (Atomic) flex boots to 15° past their natural forward lean. This is a real world flex range. Only going to 10° doesn't show the real progressive ramp up that many boots have. It's leaving out part of the flex curve that people will encounter.

Do you pull data from on hill testing too? Using strain and pressure sensors to measure boot deformation/flex while skiing? That would be some interesting stuff to look at.

[shitskier]

Do you pull data from on hill testing too? Using strain and pressure sensors to measure boot deformation/flex while skiing? That would be some interesting stuff to look at.

Petrone's group is doing this. This is the hottest new freetouring setup:



https://www.mdpi.com/1424-8220/23/2/836

@onenerdykid: Can I get a job with you guys testing and building sensors rigs?

[onenerdykid]

Do you pull data from on hill testing too? Using strain and pressure sensors to measure boot deformation/flex while skiing? That would be some interesting stuff to look at.

No, not really- we simply ski the boots and make changes based on what our testers feel.

1. buy all the competitor boots.
2. our testers flex test all of the competitor boots at room temp (just like you all do when shopping for boots).
3. put them all into the robot flex tester at room temp and -20°C.
4. go ski them all and see how/if our on-snow experiences correspond to the carpet tests & measured data.

I think adding strain & pressure sensors to boots would be interesting, but when you do all of the above with people who live and breath ski boot development (especially with world class athletes who are able to give incredibly accurate feedback), it's a little overkill in my opinion. Ultimately, it's how the boot feels and behaves on snow (with its intended user group) that determines how we alter/change plastics & wall thicknesses etc.

[kamtron]

We (Atomic) flex boots to 15° past their natural forward lean. This is a real world flex range. Only going to 10° doesn't show the real progressive ramp up that many boots have. It's leaving out part of the flex curve that people will encounter.

Validated!

[LeeLau]

Ultimately, it's how the boot feels and behaves on snow (with its intended user group) that determines how we alter/change plastics & wall thicknesses etc.

Yes - a thousands time yes. Now someone go tell the micro-parsing Germans always wanting to quantify everything and ordnungsliebe and shit.....

[Tjaardbreeuwer]

Yes - a thousands time yes. Now someone go tell the micro-parsing Germans always wanting to quantify everything and ordnungsliebe and shit.....

Hmm. Of course it’s true, but I do think there is value to objective data as well.

The problem is that in the real world, most of us can not go out and test the gear (boots in this case), in all relevant situations. If we could, then we’d be set. Like @onenerdykids testers, we would test the gear, and choose what works best for us subjectively. Done.

But, we don’t have that option. So, we are looking at reviews. And with the subjective reviews, there is often a wide range of opinions on the same product, and perhaps more critically, it is rare to find reviews comparing all the options a certain consumer is considering.

Certainly for that, a good, representative, set of objective tests can help.

The challenge of course, is figuring out what and how to measure that correlates well to real world performance.

Of course this is the whole “Blister labs” discussion.

[LeeLau]

Tjaard I'm just poking fun. My wife is half German

[Marshal Olson]

The challenge of course, is figuring out what and how to measure that correlates well to real world performance.

One other point here is that many folks are operating with different constraints. For me, with respect to touring boots, I dream of reliably determining:

(1) internal shell length at the size breaks
(2) instep height at the navicular for corresponding size breaks
(3) actual internal shell width across the designed met heads (not the marketing last)
(4) shell friction through ROM without the liner
(5) internal shaft diameter of the ankle w/ a standardized amount of buckle compression

of course, I substitute all of this by going to a ski shop that stocks basically everything and shell fitting. But not everyone has Skimo.co 3 miles from their house.

[Benneke10]

of course, I substitute all of this by going to a ski shop that stocks basically everything and shell fitting. But not everyone has Skimo.co 3 miles from their house.

Preach!

Luckily Backcountry.com has flat rate $7 return shipping even on large boxes with several pairs of boots, and they stock most touring models

[Consigliere]

Great video, thanks for posting.

He talks a bit about "stance" - this isn't really something I've thought of when trying to find a boot. Does anyone know of more resources that talk about stance? I'm trying to map it on to my experiences with various boots I've tried on.

(2) instep height at the navicular for corresponding size breaks

Having a high instep, I wish there was more data on this - it's probably the most critical part for my fit.

of course, I substitute all of this by going to a ski shop that stocks basically everything and shell fitting. But not everyone has Skimo.co 3 miles from their house.

+1 - It's really hard to compare and contrast. Finding a shop that stocks most of the boots from all manufacturers is impossible in a lot of places.

[Tjaardbreeuwer]

@consigliere: Marshall did:

https://www.tetongravity.com/forums/...a-and-the-like

[shitskier]

Great video, thanks for posting.
He talks a bit about "stance" - this isn't really something I've thought of when trying to find a boot. Does anyone know of more resources that talk about stance? I'm trying to map it on to my experiences with various boots I've tried on.

@Consigliere

I've been geeking out on this lately. He's referring to ramp and forward lean, which affect your fore/aft balance. Most bootfitting resources don't talk a lot about this, and when they do they almost always say this should be based on your ankle dorsiflexion. Unless you have limited ankle mobility, this is bullshit.

Assuming you keep your center of mass over your foot, ramp and forward lean will determine your whole body position as you move up and down.


For me, I need a ton of forward lean to be able to get low on skis without getting backseat, but this is dependent on your body proportions. It's also dependent on your ski style, what stances you typically use, and where you want the center of mass to be.

If you want to experiment, step into your skis on flat ground and see how standing up and squatting down affects your balance. Then try adding or removing lean. (Adding is easier via shims between rear cuff and liner).