AT Boot Flex Comparative List by model

[Tony]

The list has been (un-scientifically) compiled by:

a) Maggots' input comparing their stiffest AT/Freeride boots' flex (Endorphins, Tornado, Aero Freeride) against their alpine Sollies. A single alpine boot brand's flex range (in this case, Salomon) makes for better comparability in contrast to mixing flex ranges from Lange, Tecnica or Nordica.

b) Once the stiffest AT/Freeride boots flex ratings have been established, the ratings of the softer AT boots were established down the flex range fine-tuning up or down according to, again, maggots' input.


Alpine boots used for comparison

100 - Salomon X-Wave 9 ("a notch or two above Denali TT")
95 - Salomon Gun ("Endorphin not as stiff")
90 - Salomon X-Wave 8 ("the Endorphins are comparable", "if my x-wave 8 is really a flex index of 90, instead of 80 like I thought, I could agree with the fact that the FR Aero is an 80")



THE LIST (stiffest ---> softest)

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120 - Garmont Shamen*

110 - Garmont Astral*

100 - Black Diamond Factor, Dynafit Titan, Scarpa Hurricane*

95 - Scarpa Typhoon/Skookum (stiff tongue), Garmont Endorphin, Garmont Axon

90 - Garmont Radium, Dynafit ZZeus, Dynafit Aero Freeride (4-buckle)

85 - Scarpa Tornado/Pro (black tongue), Scarpa Spirit 4 (black tongue), Garmont Adrenaline, Dynafit Zzero CF 4-buckle, Black Diamond Method, Salomon Ellipse e2

80 - Scarpa Denali XT/TT, Scarpa Spirit 4 (green tongue), Lowa Struktura Rodeo/Pro, Dynafit Zzero PX 4-buckle

75 - Scarpa Spirit 3, Garmont Megaride/G-Ride, Lowa Struktura Evo, Dynafit Aero Speed (3-buckle), Dyanfit Zzero CF 3-buckle

70 - Scarpa Matrix, Old Scarpa Denali (4-buckle red shell), Dynafit TLT 700

60 - Scarpa Laser, Garmont Dynamite, Dynafit TLT 500 (2-buckle + strap), Scarpa F3

50 - Scarpa F1, Garmont Megalite, Dynafit TLT 4 Evo (3-buckle), Dynafit TLT 4 Lite (2-buckle + strap), Dynafit Zzero 2C (?)

40 - Scarpa F1 Race (2-buckle, no strap), Dynafit TLT Race Pro (1-buckle + strap)

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(*) You can argue that these are not proper AT boot as they lack a walking mode. Nevertheless, they are not alpine boots either as they have Vibram/rubber soles.


Flex Rating Guide for AT Boot Jongs:

120-100 flex rating boots currently in the market (except for BD Factors) are "hybrid" boots. They are neither proper AT boots (no walking mode) nor alpine boots (have Vibram soles). These features make them most appropiate for the sidecountry skier that wants the stiffest boot with Vibram soles for the ocassional bootpack through rocky terrain. He probably ski them with Marker Dukes too, so best for 10% uphill / 90% downhill.

95-85 flex rating is the new breed of "freerando" boots good for single-day BC forays and mixed on-piste/sidecountry use. Given the improvements in stiffness, many users buy these boots as their "quiver of one" for both piste and off piste skiing. They all come with 4 buckles, the stiffest tongues, both ISO and DIN-compatible soles and are best for 20% uphill / 80% downhill.

80-75 flex rating used to be the stiffest boots you could get 3 years ago. They are softer boots than the Freerando variety, light enough for extended touring but with enough stiffness for decent downhill performance. Probably this is the most popular category epitomized by the Scarpa Denali (in its various evolutions), well-liked among guides and patrollers in both North America and Europe. Might be the best choice if you are planning to have only one AT boot, as they provide decent downhill performance but they are also light enough for multi-day hut touring. Targeted best for 35% uphill / 65% downhill.

70-60 flex rating is the quintessential lightweight multi-day hut-to-hut touring boot. When fewer options were available, the Scarpa Laser was for many years the most sold AT boot in the world. If you mod them with stiffer Denali/Flexon tongues, thermo liners and Booster straps, it will make them at least 15-20 flex stiffer. Think Chamonix-Zermatt: 50% uphill / 50% downhill.

50 flex rating is excellent for the alpinist/ski mountaineer that needs a superlight boot for winter/glaciar approaches and wants to regularly ice/rock climb or walk in them with crampons on. Almost all have two buckles and are best for 70% uphill / 30% downhill.

40 flex rating is the land of lycra-laden Euro randonee racers. These boots are uber-specialized, stripped off to the max to minimize weight, provide minimal descent support and probably not worth it unless your VO2 max is up there with Lance's. Think Pierra Menta: 90% uphill / 10% downhill.

[pechelman]

Owning the freeride aero and an xwave 8, theres no way my dynafit boot is stiffer than my alpine.

Id maybe say the freeride aero is more like a 50 or 60 compared to the 80 of my xwave. I have however ground off the flex limiting tabs from last years version, but even before that, they were not stiffer.

and if this is really the case, then a lot of those other flexes need to be bumped down as well cause those are also high. Ive tried on a megaride, and it was definitely a flex index or two below the freeride aero.

also tried on a laser and that felt one'ish below the megaride.

[laseranimal]

I have no frame of reference to Lange's flex scale but to use your numbers

85 Lowa Struktura Evo
75 Dynafit TLT 700
and would concur on the 50 rating for the F-1

[Idris]

Not sure which areo freeride pechelman has but mine are the aero 4 and are way stiffer than any other AT boot I've flexed. They would be 100 to 110 on that scale. They are a fair bit stiffer than my roomates endorphin and my buddies tornados. Did you grind down the cuff lock (little catches on the inside of the cuff that catch onto the shell, stiffening forward flex)?

My lowa Struka evos would be 70-80 on that scale.

[Tony]

Pechelman, I tend to concur with Idris on the Aero Freerides. Its one of the stiffest AT boots out there. Sorry, I can comment about how a Lange 120 compares to an X-Wave 80, but my guess would be the Sollys are significantly softer. The 50-60 index is more common of a kiddie's ski boot. And IMHO kiddie's ski boots flex resembles that of the F1. Maybe some more people can add to the discussion.

Idris, I agree the Aero Freeride is stiffer than the Tornado, but stiffer than the Endorphin?

So we have an issue with the Aero Freeride: Pechelman says 50-60 and Idris 100-110. That's a big gap. I am leaving at 85 (to cut the difference) for now waiting for further discussion.

Added the Lowa Struktura Evo with an 75 index (cut the difference between Laseranimal and Idris).

I concur on the Laser: it's a bit less stiff than the Matrix and Megaride. I lowered to 60.

I know this is not highly scientific (to say the least) but if people give out his thoughts we might compile something useful.

[marshalolson]

the endorphin is no where anywhere near as stiff as a salomon gun boot (95 flex).

though the relative terms flex of the AT boot to one another seem pretty spot on in my experiance...

[mntlion]

a normal raichle tounge will make most AT boots up to a 80-100 flex

add a extra power strap around the liner and an extra around the shell (booster strap) and +10

adrenalines are 90-100 on that scale

old denalies are 70

megarides (skibee's) are about the same?

[pechelman]

well i will say that boot flexes from manufacturers are very subjective

My gf's little bro has a pair of xwave 6's that are the same size as mine and Ive tried his on in comparison to the freeride aeros and they honestly feel very similar. If anything, the xwave 6 is a tad stiffer due to a higher cuff.
These xwave models are from the same year as well, 03/04 I beleive. (the all black models)

I did grind the tabs off because I didnt like the brick wall id flex into, nor did I like what the rest of the shell did when it hit those flex limiter tabs. When I did have the tabs, I do remember the boot feeling a bit stiffer, but only maybe up to say a 70 or so on solly's scale.

This is just my experience, so take it for what its worth.
My experience, however, does agree with your relative location and stiffness of each boot.

having said all of this, even without those tabs, I feel the boot is more than stiff enough for any descent, and definitely not the limiting factor.

edit: for reference, and not sure if it matters too much, im referring to 27 mondo shells, stock liners (thermo in the fraero), and Im 5'10 170.

edit2: I have tried on a pair of lange wc130s? or 120?, I forget, and it was a very stiff boot, but honestly, I would guess it would only be a couple indicies above a solly 80. Also worth mentioning, which could be effecting my judgement, is that the solly boots Ive tried on all have a very upright cuff position, possibly making it feel stiffer than it actually is, especially in comparison to the extreme forward lean on stock FR Aeros and on Lange boots.

[Chaka]

Originally Posted by mntlion

a normal raichle tounge will make most AT boots up to a 80-100 flex

add a extra power strap around the liner and an extra around the shell (booster strap) and +10

adrenalines are 90-100 on that scale

old denalies are 70

megarides (skibee's) are about the same?

Yes, agree with mtn lion's Flexon mod comment... I'm guessing I've bumped my lasers up to around 75ish with the mod.

[corn dog]

The TLT 4 is way soft, maybe the softest thing ever. Mine are old though. The 500/700 series are also really soft. I'd put them down around the F1/TLT race.
The F1 is a different in that its forward flex is softer but its got pretty good lateral support. I think the bellows makes the forward flex softer overall and a little odd feeling.

A friend just picked up some endorphins, he's been on XWave 8s for a few years. Says the endorphins are comparable.
Another edit, the effects of a stiffer tongue are lessened a bit as the lower shell deforms quite readily.

[Tony]

Lowered the Endorphin from 100 to 90, given marshal and corn dog comments.

I also lowered the next two categories to accomodate for the further posts.

Mtlion, by old Denalis you mean the red ones pre-XT?

Corn Dog, IMHO Dynafit TLT 500/700/4 are stiffer than a Dynafit Race Pro, hence stiffer than an F1. Maybe someone else will comment.

[laseranimal]

I dunno I think the dynafit 700 is WAY stiffer then the F1. Its not as stiff as a Struktura or Denali but its a lot closer to those two then it is to the F1

I'd say stiffer then a laser/matrix and softer then a spirit 3

[mntlion]

Originally Posted by Tony

Mtlion, by old Denalis you mean the red ones pre-XT?.

red ones, 4 buckles, where the stiffest thing around 5+ years ago.

[XtrPickels]

Keep in mind that this scale doesn't exactly match up with manufactures scales. The Flex in this scale is relative to the boots, maybe it ought to go 1-10 like the marshoflexometer for skis?

People get confused all the time trying to compare boots flexes across brands.

Originally Posted by idris

Did you grind down the cuff lock (little catches on the inside of the cuff that catch onto the shell, stiffening forward flex)?

doesn't grinding those down create softer flex? Once the cuff stops moving on the tabs, its distortion of the shell which ought to be harder to flex than a pivoting cuff?

[pechelman]

^^ yea it makes the flex stiffer after the cuff locks engage or softer after you grind them off

did I type something wrong?

I ground mine off because it wasnt a nice progressive feel and it did significantly distort the rest of the boot which I did not like. I could feel it moving around on my forefoot.

[Tony]

Originally Posted by XtrPickels

Keep in mind that this scale doesn't exactly match up with manufactures scales. The Flex in this scale is relative to the boots, maybe it ought to go 1-10 like the marshoflexometer for skis?

People get confused all the time trying to compare boots flexes across brands.

There's no manufacturer's flex index scale for AT boots. Hence the purpose of this thread.

The flex index of alpine boots is not comparative among different brands. Agreed. But among the top models (>90-100) for leading brands (Lange, Salomon, Nordica and Tecnica) they don't seem to be that far off.

I differ in making it a 1-10 scale like marshoflexometer for skis because:

1) the 1-10 marshoflexometer for skis has to be made up because there is no formal info on ski flex from manufacturer within their own lineup. But boot manufacturers do provide this info so might as well use it as a benchmark.

2) folks would like also to measure and have a rule of thumb against their current alpine boot.

Just my take on it, anyone can convert this to 1-10 scale afterwards.

[Fritz]

Nice work on this. Are you referring to the Scarpa Tornado or Tornado Pro? FWIW the Tornado Pro comes with two tongues, a stiff black one and a soft white one (that's what she said).

[wilcox510]

I have megarides with stiff Krypton tongues and Krypton ID liners in them. They are significantly stiffer than stock. However, one thing to keep in mind is that swapping the tongues only really changes the forward flex. They are stiff pretty soft as far as lateral support goes. Thats one thing I've heard several people say about Adrenalines, they arent that much stiffer in forward flex than megarides (especially with a stiffer tongue) but the lateral and rearward support is apparently significantly better. Anyone here actually seen/flexed/fondled the Zzeros? KR on couloirmag.com is giving them very good reviews.

[XtrPickels]

Originally Posted by pechelman

^^ yea it makes the flex stiffer after the cuff locks engage or softer after you grind them off

did I type something wrong?

I ground mine off because it wasnt a nice progressive feel and it did significantly distort the rest of the boot which I did not like. I could feel it moving around on my forefoot.

On my re-read I noticed that the paranthesis was around the whole statement. Which means he was saying the tabs stiffen the flex and not grinding them off stiffens the flex.
My bad

[Jax]

The Shamen, Garmont's new offering for '07-08 is FI 120. The ladies version, the Astral, will be a 110. One thing to note is the lack of touring mode in these boots, but they do come with a DIN/ISO sole and an AT sole.

PM me for more info.

Available 7/1/7

[Spats]

I'm with everyone else on the "Aeros are stiff" crowd.

I respect pechelman's engineering knowledge and opinions, but all I can think of is that he has a weird pair, because they were worlds stiffer than any other AT boot I tried (Spirit 3, Megaride, Laser, Matrix, etc.) It wasn't even a comparison.

[weavin]

Chippin' in with another boot.
Garmont Megalite.
60 seems about right. Comparable to the Lasers.
Wishin' I had something a bit stiffer but still light.
Next year.
Nice thread.

[laseranimal]

could the reason there's confusion on the Aero be that there's two models of the Aero?


there's the 3 buckle Aero Freeride


and

there's the 4 buckle Freeride Aero




I personally thought it wasn't a great idea to have two boots with the same name just flip flopped, maybe thats part of the confusion?

[Tony]

The 3-buckle boot in the first pic is the Aero Speed TF (wrongly called 3-buckle Freeride in the Life-Link site).

The 4-buckle boot in the 2nd pic is the Aero Freeride TF.

TF means ThermoFlex

Two different boots.

[laseranimal]

yup, I realize its two different boots, didn't realize it was called Aero Speed

But I've seen it in MULTIPLE magazine reviews with the Aero Freeride title