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Explain to me how this boot flex rating thing works

post #1 of 12
Thread Starter 
I've only had one pair of boots that I bought new, when I bought them a few years ago it pretty much involves walk into a big box sport store and picked the one store clerk said that should work for me. It's a pair of salomon performa 6, which from what I gather is only 65 or so.

From what I've read on the forum, at near 200 lbs and 6' plus, I should be able to crush them like bugs and break them in two the first time I tried to flex on them. But here is the thing, I don't really find them soft (they are a bit wide around foot but that's another story). If I buckle them all at 1st notch, yeah my legs float around in them, however with my usual routine of powerstrap between tongue and shell and tighten the two upper buckles two or three notches after a few runs, they seem to work fine. I thought I am an intermediate skier, since even beginners my size were recommended to get 80/90 flex boots they should be way too soft for me right?

But maybe I'm way overestimating my skills, so we'll take it out of the equation. Buckling them to my usual position, I can stand on two toe pieces only, and put all my weight on my shins, the shell still flexes just a little. It's only when I put all (okay most, need hands on wall to keep from toppling over) my weight on one shin, the shell flexes a bit more (I put my hand between the 1st and 4th buckle and feel the distance shortens). The shell seems pretty stiff and can support my weight well, despite the low flex rating.

So how does this work? I'm quite confused by this to be honest.
post #2 of 12

It's called dynamic loading.  If you lean against a door with all your weight the door is fine.  If you take a run at it you might just knock your way through it (depend on the door).  If you sit a 10 lb sledge hammer on brick there is no problem; swing that hammer and you can break the brick.  Your car sits on its springs just fine, hit a big bump at speed and the springs bottom out. 

 

Your boots are too soft.  They allow you to get too far out of position before transferring a good amount of force to your skis.

  

When you upgrade them to a stiffer boot, find a good boot fitter first.

post #3 of 12
Quote:
Originally Posted by jzmtl View Post

I can stand on two toe pieces only, and put all my weight on my shins, the shell still flexes just a little. It's only when I put all (okay most, need hands on wall to keep from toppling over) my weight on one shin, the shell flexes a bit more (I put my hand between the 1st and 4th buckle and feel the distance shortens). The shell seems pretty stiff and can support my weight well, despite the low flex rating.

So how does this work? I'm quite confused by this to be honest.

You're doing it wrong... stand with the boot soles flat on the ground, bend at the knees and ankles to apply pressure to the front of the boot, it will flex forward with your shins. Avoid bending at the waist or dropping your hips back like you sitting down in a chair, your pelvis (and entire upper body) should move forward with your knees.

 

Standing on your toes and leaning against a wall? Not a ski movement.

post #4 of 12

Flexing a ski boot is a subtle skill.  Especially as a skier improves.  If you look at videos of very good skiers, can you see their feet and ankles move as they turn?

 

Note that a "flex number" is not an industry standard.  It's only relative to a brand.  Meaning a boot from one brand that is called "90" is not necessary the same "flex" as another brand.  Bottom line is that once you find a good boot fitter, then you stand the best chance of getting in a boot that is good for your level of skiing and the shape of your feet and calves.

 

Put "boot fitter montreal: epicski" into Google and you should find some relevant threads.

 

Good luck shopping!

post #5 of 12
Thread Starter 
Quote:
Originally Posted by Ghost View Post

It's called dynamic loading.  If you lean against a door with all your weight the door is fine.  If you take a run at it you might just knock your way through it (depend on the door).  If you sit a 10 lb sledge hammer on brick there is no problem; swing that hammer and you can break the brick.  Your car sits on its springs just fine, hit a big bump at speed and the springs bottom out. 

Your boots are too soft.  They allow you to get too far out of position before transferring a good amount of force to your skis.
  
When you upgrade them to a stiffer boot, find a good boot fitter first.

Yes, static force is not as strong given equal mass behind it, but consider when doing this my heels are lifted off the bottom of boots which don't happen when you flex, I'm putting a lot more mass onto it.
Quote:
Originally Posted by Whiteroom View Post

You're doing it wrong... stand with the boot soles flat on the ground, bend at the knees and ankles to apply pressure to the front of the boot, it will flex forward with your shins. Avoid bending at the waist or dropping your hips back like you sitting down in a chair, your pelvis (and entire upper body) should move forward with your knees.

Standing on your toes and leaning against a wall? Not a ski movement.

No it's not, but the force is in the same direction, and the boot shouldn't care if a movement is ski movement or not, as long as the force applied is the same, right?

Quote:
Originally Posted by marznc View Post

Flexing a ski boot is a subtle skill.  Especially as a skier improves.  If you look at videos of very good skiers, can you see their feet and ankles move as they turn?

Note that a "flex number" is not an industry standard.  It's only relative to a brand.  Meaning a boot from one brand that is called "90" is not necessary the same "flex" as another brand.  Bottom line is that once you find a good boot fitter, then you stand the best chance of getting in a boot that is good for your level of skiing and the shape of your feet and calves.

Put "boot fitter montreal: epicski" into Google and you should find some relevant threads.

Good luck shopping!

Sometimes I do wish I live next to one of you pros, so you can tell me in person if I'm actually flexing or not, and how much I suck. biggrin.gif

Anyway new boots is in the plan when budget allows, but I'm trying to understand how everything works so I don't walk into it blind like last time.
post #6 of 12
Quote:
Sometimes I do wish I live next to one of you pros, so you can tell me in person if I'm actually flexing or not, and how much I suck. biggrin.gif

Anyway new boots is in the plan when budget allows, but I'm trying to understand how everything works so I don't walk into it blind like last time.

Small investment in a group lesson next Dec might be well worth it.  Especially if you can go mid-week.

post #7 of 12
Thread Starter 
It would, but I don't think there are any available in English. I'll ask anyway next time.
post #8 of 12

There is a lot to understand about boots.  Most of it doesn't matter unless you are in  a correctly fitting boot.  You can take two similar boots and get different results from them based on how they fit your foot/leg.  Even if they are the same size; might not be shaped the same. A stiffer boot might flex more easily than a softer one if the softer one doesn't fit you correctly and the stiffer one does.

 

For what it's worth, I'm 5"7" and 155# in a 120 flex.  Physically you can (at your size) crush pretty much any boot out there while standing in the store.  Skill level and balance comes into play too.  You also need to consider if you're going to do a lot of tree or bump skiing.

 

You don't need a stiff boot to ski.  Many folks are going to softer boots.  Many times this year I skied with my boots completely unbuckled; just the booster strap secured.  Stiffness in the boot usually means there is a quicker transfer of information to the ski.  To newer skiers, this can work against them because they could end up over steering or get knocked back when the ski communicates back to the skier.

post #9 of 12
Thread Starter 
Hmm, maybe I am already crushing it without knowing. Perhaps the term "crushing" isn't the best description because it implies the leg section will bow forward significantly, which not even my current soft boots will do.

Oh well, all is just speculation now, going to be 8 months before I can get on the slope again.
post #10 of 12
Quote:
Originally Posted by jzmtl View Post

Hmm, maybe I am already crushing it without knowing. Perhaps the term "crushing" isn't the best description because it implies the leg section will bow forward significantly, which not even my current soft boots will do.

Oh well, all is just speculation now, going to be 8 months before I can get on the slope again.

 

Think of it more as "bottoms out" as in no more range of motion.

post #11 of 12
Thread Starter 
you know that description makes a lot more sense than crushing.
post #12 of 12

Here is my take on boot stiffness (wt, size and age taken out of the equation).

 

Soft boots (low number) have a slow response time for getting the input of the skier to the ski, so they are a little more forgiving in terms of errors and hence must beginners start in very soft boots as they are slow to respond.

 

Stiff boots (high in number) are general very responsive and therefore unless the skier has full control any error will be greatly magnified or greatly rewarded with immediate response.

 

So whats the right number depends on how you ski and what you are skiing.  Skiing powder, like a little on the softer side a little more forgives is required.  Skiing ice and hard pack stiffer numbers are required to get the response and set of the ski.  Both, a little bit of a compromise with something in between.

 

Add back in wt, age, size  and ability a good boot fitter can give you a good starting point.  Finally its personal preference at the end when you get good.

 

For me I've always skied stiff boots, and would easily steer anyone towards stiff boots (because they work for me and its what I believe).  Is it right, honestly don't know but what Ghost said is correct and your boots are likely on boots too soft.  I'm 30lbs less (likely more aggressive skier) and ski a  Lange WC130 and this is the softest boot I've had in 20 years.  What this boot loses in forward stiffness, it makes up for in side to side stiffness and a better overall shell stiffness.  I won't go lower than a 130, as I said previously, that's just me.

 

Hopefully that give you an ideal of what manufactures are trying to convey.

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EpicSki › The Barking Bear Forums › On the Snow (Skiing Forums) › Ski Gear Discussion › Explain to me how this boot flex rating thing works