Boot flex across different brands

**jerr** · 08-09-2007, 03:34 AM

I was chatting to a boot fitter the other day and he said the flex number (80, 120 etc) should be ignored because there is no consistency between brands. Basically that it is arbitrary and meaningless. Is this the case? I had always thought it was a measure of some sort?

**SiSt** · 08-09-2007, 04:00 AM

I thought the same thing, but then saw that Dalbello had a different system and started doubting... Started a thread on this topic over at skibuilders.com yesterday, see link.

http://www.skibuilders.com/phpBB2/viewtopic.php?t=928

**stuckathuntermtn** · 08-09-2007, 10:13 PM

The numbers are mostly arbitrary.
Are a Lange Comp 130 and a Nordica Doberman 130 similar? Yes
Are they the same? Nope

**Voltron** · 08-10-2007, 08:30 PM

Numbers? I buy boots by colour.

**Plakespear** · 08-11-2007, 07:54 PM

Personally, I would like to find some paint-by-numbers boots.

But in all seriousness, there is no industry standard for boot flex, unlike say the DIN standard for binding release values.

Squatch · 08-11-2007, 08:40 PM

to elaborate on plakespear's post: the way a boot flexes is incredibly subjective, depending on the mechanism, pivots, and overall plastic in the rest of the boot. Not to mention a fairly good portion of a boot's flex is the plastic deforming.

**72Twenty** · 08-12-2007, 12:14 PM

I use the number system to gauge boot flex, but that is because I stick with one brand of boots (Lange); so the system works when comparing different models of the same brand.

Squatch · 08-12-2007, 03:14 PM

Yes and no. Even within brands, the numbering is not linear. There is a noticeable difference between the under 100 solly falcon/gun boots, but not so much between the over-100 falcons. I.e., the difference between a 90 and a 110 is larger than a 110 and a 130

**72Twenty** · 08-12-2007, 09:03 PM

I guess you're right... My Lange L-10's were stiffer (when new) than my 120 FR's, come to think of it...

**skiingsamurai** · 08-13-2007, 08:47 AM

Originally Posted by Squatch

Yes and no. Even within brands, the numbering is not linear. There is a noticeable difference between the under 100 solly falcon/gun boots, but not so much between the over-100 falcons. I.e., the difference between a 90 and a 110 is larger than a 110 and a 130

I agree 100% In the nordica line I could outflex the supercharger (120 i think) and not outflex my speedmachine 14's (120-130)

Supprisingly I outflexed the superchargers easily, even though theyre a stiff boot. I ended up going with the SP14 not only becuase it fit, but because i couldent outflex it. The thing is stiff as cement.

**jerr** · 08-14-2007, 03:18 PM

So, wtf are these seemingly random numbers suppose to have measured? There must be an answer god damn it!

**skiingsamurai** · 08-14-2007, 03:39 PM

to answer your question with a related totally unrelated question:
where does a car company get the numbers they throw in the model name
BMW, Lexus, Benz, for ex. I think Someone came up with the flex index idea and no one ever bothered to standardize it. That is a TOTAL GUESS, but it seems to fit.

I just use them as a reference, but still try different ones on to compare

**powdog** · 08-21-2007, 12:52 PM

The flex numbers are only good for a single alpine boot manufacturer, but it all depends. I find the flex between Nordicas and Salomon about the same (last year's models) mid-top-end. I found that the Raichle F-1's were too soft, of course, it might have been the shell tongue. No way in hell could I fit into a Flexon Comp, the fit was fine, but the instep was too low. I like the Lange Freeride Comp 120 and the Comp 120 MF (mid-fit), but no shop had them in a 26.0. What is it about ski shops? Everyone wants 26.0 boots, and it seems that is the size that goes first.

**Damian Sanders** · 08-21-2007, 01:13 PM

Originally Posted by jerr

So, wtf are these seemingly random numbers suppose to have measured? There must be an answer god damn it!

Answer:

They are an rough guideline between models in a line, and also a rough guideline between different brands.

That's it.

Boot flex is so variable do to different boot sizes, fit, modifications and ambient temperature, that it's pretty meaningless to make a hard specification. Plus it would be way too complicated for consumption by the public.

I'd bet the that the boot engineers DO test this stuff, but they probably don't like releasing the data, etc, since it's company propetary.

It would not be too hard to build a testing jig based on a prosthetic foot with some force and measurement gear, if you HAD to know exactly how stiff stuff was.

Key thing to do is to buy the shell that fits you the best and the design that suits your needs, and try to get the stiffest flex model with the best liner in the lineup. Then soften it to your tastes with the help of a good boot fitter.

It's also important to note the actual stiffness vs. the flex pattern. Some boots have a nice liner flex that gets progressively stiffer in a consistant manner, while other as soft for a bit and then reallt stiffen up at the end. Some boots are also much more effected by ambient temperatures than others - when it's cold they are very stiff, and when it is warm, they get very soft.

**Arno** · 08-22-2007, 02:07 AM

No standardisation has certainly been the case in the past. I have heard that some boot mfrs are now trying to standardise the numbering, although it doesn't look like they have been publicising it too much. Saw this in a thread on another forum started by a professional bootfitter so it does have some credibility I hope. I'll post a link if I can find it.

edit: found the link:

http://snowheads.com/ski-forum/viewtopic.php?t=9765

Couple of interesting points covered earlier this week regarding boot flex.

Your ski boot flex rating is going to be standardised. There are already certain manufacturers using the scale.
The flex rating of a given boot will be the measurement of energy required(N) to flex the boot through 10 degrees(angle) at 23 degrees(Celcius). I.E. Your Tecnica Diablo Race, 110,130,150,160.
Some manufacturers will then divide this by 10 to give a scale 1-10 on intermediate boots.

The Plastic used by 80% of boot manufacturers will be a French B.A.S.F. Poly-Ether. This will have a greater resistance to temperature flex fluctuations at common temperature(+5 to -5), however, between room temp and -15 your average ski boot will become an amazing 5 times stiffer.

**addict** · 08-22-2007, 02:41 AM

Originally Posted by skiingsamurai

to answer your question with a related totally unrelated question:
where does a car company get the numbers they throw in the model name
BMW, Lexus, Benz, for ex.

These car companies usually have 1 number referring to the car size and 1 to the engine size, in litres. Ie. a BMW 130 is a small car with a 3L engine, a BMW 318 is a mid size with a 1.8L engine. Similarly a Lexus LX450 will have a 4.5L engine and so on.

Maybe they're more related than the boot flex numbers? Definitely not arbitrary.

**jerr** · 08-22-2007, 07:05 AM

Originally Posted by Arno

No standardisation has certainly been the case in the past. I have heard that some boot mfrs are now trying to standardise the numbering, although it doesn't look like they have been publicising it too much. Saw this in a thread on another forum started by a professional bootfitter so it does have some credibility I hope. I'll post a link if I can find it.

edit: found the link:

http://snowheads.com/ski-forum/viewtopic.php?t=9765

Thanks for the info. I was looking for an answer that involves a bit of science.