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Matching boot flex and ski stiffness

William H

In the parking lot (formerly "At the base lodge")
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Mar 27, 2018
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I'm in my fourth year skiing, and have skied about 80 days total. Almost all of those days have been on a pair of Rossignol Experience 77 skis and Technica Cochise 100 boots. I'm 5'11", 180 pounds. I feel good skiing just about any groomed run on the east coast, and am just starting to enjoy skiing just off piste and in trees when the snow is good. I ski primarily on the east coast, but get out west for about 5 days a season.

I've thought for a long time about upgrading my skis, and a couple weeks ago pulled the trigger on a pair of Nordica Enforcer 93s. I had the chance to ski them for the first time this past weekend, and absolutely loved them. The stability at speed and edge hold are miles ahead of the Experience 77s I had been skiing.

The new skis got me wondering, though, if it's time I think about moving to a stiffer boot.

Do you all take into account ski stiffness and width when thinking about boot flex? Are there signs that would indicate a boot is too flexible for a skier? Or am I just getting in my head when I just keep skiing?

Thanks in advance for your thoughts and feedback!
 

jzmtl

Intermidiot
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Apr 25, 2017
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323
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Montreal
It's probably time to upgrade to a stiffer boot, but once you go up there's really no reason to back down even on a softer ski.

I upgraded from 110 to 130 and kept the 110 thinking I'd use it with my all mountain skis while 130 with my SL and GS. But after using 130 for some time, going back to 110 is unbearable, feels like it's going to collapse under pressure. 110 has since been retired to "ski with wife on green trails" duty since it's quite comfy all day long.
 

Ken_R

Living the Dream
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Denver, CO
Read this: https://theskimonster.com/blog/posts/ski-boot-fitting-flex-width-liners-hike-modes-and-shell-design/

excerpt:

"
Yes, it requires more energy to make an Enforcer 100 bend than a Navigator 80. The ski boots job is to make the ski bend, stiffer boots transmit energy more efficiently. To bend a ski like the Enforcer, you’ll need a 110-ish – 130 flex, for the Navigator 80 you could be on anything from an 80 – 120 flex boot – it’s not an extremely demanding ski but it can hang.

Going super stiff isn’t necessarily the answer. If you have a ski like the Enforcer or Enforcer 110, even a Head Supershape Rally, a WC boot, like a Dobermann 150 is too much boot. I suppose you could make an argument that going down an extremely technical exposed line in garbage snow it’d be helpful, but that’s it.

What flex index ski boots are appropriate for you?

It’s tough to say what the correct flex is for a specific person without a bootfitter or coach seeing the skier in the ski boots – part of the reason there is a range of flexes that could work for a specific ski. Determining the correct flex index depends on; ankle mobility, strength, weight and what skis your on. A lot of skiers under buy on the boots and over buy on the skis, i.e that 90 Flex boot for $399 can’t power an Enforcer 100 – you’ll get by, but you’re not getting everything out of the skis that you should be.
 

Pete in Idaho

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Just to be contrary. There is a point where a really stiff boot will be as bad for you as a real stiff ski. Either one you won't be able to flex and that will not be good for your skiing. Be careful don't be macho and think you need a really stiff boot to flex a 93 Enforcer. Also have to take into consideration your weight, strength, ability, , experience, are you flexing your ankles, how are your turns etc. etc. etc. Proceed cautiously.
 

CalG

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Someone is going to need to show the mechanics of this statement.

"Yes, it requires more energy to make an Enforcer 100 bend than a Navigator 80. The ski boots job is to make the ski bend, stiffer boots transmit energy more efficiently. To bend a ski like the Enforcer, you’ll need a 110-ish – 130 flex, for the Navigator 80 you could be on anything from an 80 – 120 flex boot – it’s not an extremely demanding ski but it can hang."

Only CoM and loading can bend a ski. A change in the location of the CoM can change loading of one end of the ski at the expense of the other. Only "forces" can bend a ski and a "stiff boot" can NOT generate forces by themselves.

I am eager to understand the mechanics and resolution of loading that supports the "stiff boot is better able to bend a stiff ski because it is more efficient" proposition.
 

eok

Slopefossil
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Nov 18, 2015
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Referencing the original post...

So, you've been using your Cochise 100 boots for about 4 years now. They might be pretty packed out by now. One possible thing to consider: replace the liners with stiffer ones - like an Intuition Pro Tongue model. This will stiffen-up the Cochises maybe 10 points, maybe a bit more.
 

PTskier

Been goin' downhill for years....
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William, you asked a question with no answer...or a million answers.

Boot flex depends on personal preference and skiing style. I'm 6', 175#, ski at a moderate pace, and I really like my 130 flex boots. Stiffer flexing boots transmit leg movements to the skis more quickly and provide something to lever against when one needs to get re-centered. I ski powder, hard pack, bumps, and everything else in these boots just fine.

Also consider that there is no industry standard boot flex rating. Each boot maker has their own rating scale. One brand 110 might equal another's 100, and another's 120. My current 130 flex rating boots are stiffer than the Nordica 130 boots they replaced. I know how to cut them down to soften the flex, but I like how they ski as they are.
 

Dave Marshak

All Time World Champion
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I find softer boots are more forgiving and make it easier to flex and extend, especially in moguls. I also don't think I need a boot that's more precise than I am. I'm happy with Lange RX110s. I might want something stiffer for slalom racing, maybe not for speed events. I never felt a boot "collapse under pressure," not even with my carving skis.

FWIW I met Tommy Moe about 6 years ago skiing at a fund raiser. He was wearing RX130s, but he had the upper bolt out of the cuff, so about 110 or 115.

dm
 

PhillyGuy

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Feb 22, 2018
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Pretty similar to you. Skied for about 5 years but get a lot of days, mostly out west.

I still have my first Cochise 90 boots, but upgraded my skis to Blizzard Brahma 180. I'm on the thinner side too. 5'10, 155.

I thought about upgrading my boots to a more stiff one, but I'm skiing fine with what I have even on more demanding terrains so I've haven't felt the need to upgrade right away. I've demoed Enforcer 93, 97 and Mantra with my current boots and they all work fine.
 

oldschoolskier

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Just remember one thing on the boot stiffness number, it is arbitrary in its meaning when comparing one manufacturer to another let alone within one manufacturers boot line. Used as a reference it does give a guideline as to what to expect (somewhat). Though in one it might be a 120 and another 140.

More importantly, fit comes first, then look at how the stiff the boot should be.

A good boot fitter should be able to take the guess work out of both. Remember FIT first, then stiffness.

Your important question should be who should I go and see considering I live/ski .........here for the best fit and selection.

BTW I lean towards stiff boots, however they are not for all skiers or applications.
 

john petersen

working through minutia to find the big picture!
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There are very specific parameters that a boot should conform to with you in it and flexing against it while in a ski at the temp range you will be skiing in mostly...so it is very subjective to body type, weight, performance desires, ect.

I recently got fitted in a lange 130 and am very happy...I have been experimenting with the bolts in the spine of the boot to see if one flex range is better than another and in what conditions those combinations work best in. (side note...check the tightness of those bolts regularly, though they have thread locker on them, they can still work loose over time)

I have plans to switch from the factory boot cuff strap to a Booster strap. they are available in various flexes (soft, med, hard) and have a progressive nature to them when they expand.....

I love my langes because they flex very progressively without collapsing...like my old boots were beginning to do, even with a power strap....The progressive nature of a booster strap, I have heard, and am hoping, will add to the progressive nature of the boot.

Do I have more than one pair of boots? no. more than one pair of skis, yes. each ski will behave and perform differently and that is part of the fun and challenge for me.....my slalom skis have the potential to be very lively and love to slice and dice, while my 88's stay planted and plow through crud, yet because of their dimensions, float better in powdery snow....

Maybe we should have @Philpug chime in on this...he does have some expertise in the area.....

JP
 
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William H

In the parking lot (formerly "At the base lodge")
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Mar 27, 2018
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I just wanted to check back in to thank everyone for their input and advice. I really appreciate everyone's input. I ended up visiting my local boot-fitter and ended up walking out with a pair of Tecnica Mach1 130s. I've got a late season trip planned for Snowbird and will look forward to testing them out in a couple weeks.
 

Nobody

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I used to ski in "stiff" boots, from Tecnica TNT racing to Tecnica XT17, with my P40F1@198cm (waist...IIRC about 65/66mm or even less ) then, when thinking I was aging up and needed an easier allround ski, replacing the skis with a pair of Nordica Hot Rod@178 (waist 78mm) and keeping the stiff boots (XT17). Then through the years, feeling that I could again "give" more than what the ski was able to deliver, going for a 186cmR21mt Blizzard WRC...
Then going back to the "student's desk" (so to speak), and needing to change my way of skiing (not to say, technique) to improve, realized that the stiff boot was not helping (whole leg and body "new" movement to discover and learn or re-discover and re-learn) in this venue, put down my typical male ego and went for a softer boot (first a Dalbello Scorpion 130 dialed down to 120 by removing the top connecting screw between the two pieces but, not feeling well in that boot went even softer) a Tecnica 9.8R F.I.110 (and a shorter Voelkl RaceTiger GS@175cmR17ishmt, with the tip rocker I would have preferred a 180cm, but couldn't find any). With that boot (and ski) went really back to the learning desk and worked no feeling pressure on the foot base and steering action (disregarding leg movements) then concentrating on the lower body (legs) movements, then checking the upper body...As last, checked the edge engagement...
Did the boot felt soft? Yes, absolutely, but with it, I could find and apply the right amount of force to the skis, be progressive and not abrupt in pressuring the boot tongue, and improve. Compared to this, the XT felt a bit of "on/off" boot..I was either "down" or "up" with nothing in between.
In short, the leg movements must be driven by the legs muscles and supported by the boot stiffness, not the other way round (IMHO).
Anyone who has ever skied with the boots totally unbuckled (with all buckles off not simpleengaged but not locked , power strap/booster as well) ought to relate to what I have (badly) expressed.
Do a stiffer boot have its use? Absolutely, I plan to get a 130/140 boot in the near future once the "new" fundamentals will be well ingrained again, meanwhile I got me a nice freeride boot (Tecnica ZGGP, nominally a 130 F.I. even if everyone on the ski forums keeps saying it feels a lot softer than that, which is anyway stiffer than the 9.8) and play going back and forth between the two ( 9.8-RaceTigers, then using the ZGGP with the Voelkl Race Tigers then ZGGP and Gotama, then 9.8 and Gotama) just to keep myself off the "comfort zone".
So, as usual, stiffness preferences are, for us "mortals", just that, personal preferences, dictated by many things, rational (need to drive a ski which demands it, increased/improved skills and so on) and irrational (male ego, needs to boast and swag amongst skiing buddies and so on and so forth).
But I must say that a softer boot has helped me to get "back on track".
Stats : 175ish cm tall, 82Kg. old aging guy.
In an case your question is really good and got me thinking. Usually ski stiffness is something which is not normed, except for the racing dept ones, I would like the producers to agree on a Stiffness Index (or F.I.) system for skis but given they cannot agree on a standard for boots (each producer F.I., although the number is the same, is highly subjective (relative) and valid only between boots of that specific producer , a 130 say from Lange and a 130 from Dalbello or Tecnica are not stiff to the same extent)
 

bigskymtnguy

Booting up
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Apr 14, 2018
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Flex of your ski boots should match you physiology as well as your ability. See a good bootfitter who understands anatomy, planes of motion, and ankle flexion.
 

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