Flex numbers - comparison between skis

[skibug]

Can you interpret flex numbers as stiff, soft, etc from ski to ski of different brands or would it be from ski to ski, brand specific?  E.G. flex numbers of a Strada to Stada or a Strada to an Elite.  Also, do higher numbers always mean a stiffer ski; or, is there just 1 or 2 of the readings that really mean one ski is stiffer than another?

[Horton]

No. Sadly it is generally way more messy then that. For two skis from the same mold the flex numbers mean a lot. as you go from brand to brand or ski to ski within a brand flex is just one thing that changes.

As an example the RS-1 feels softer to me than the older MPD. The Radar factory guys tell me the difference is more the bevels than the flex. Lucky for me the Strada is a totally new mold and  it feels great.

Higher numbers to mean stiffer.

So why do you ask?

[skibug]

Horton, thanks for the feedback.  Being an engineer (not a ski engineer) I always have a thirst for technical information.  I sort of had my own theory / understanding of flex; but, I figured I would inquire to those more in tune with the ski industry.  My first thoughts were that it cannot be compared from ski brand to ski brand due to the large number of variables.  I was under the impression it had to be ski to ski of the same brand, length, year, mold, etc..  There is always talk about stiffer skis, faster skis, whatever; and, I always figured it was more than just flex numbers that made the ski "feel" faster.  So you can only determine a skis stiffness as a subset of its own population.  Four identical flex numbers from two different brands of skis has no correlation to which ski is actually stiffer or "faster".

[h2odawg79]

Horton, what ever happened to the "Power Stix" idea or the like, for adjusting (tuning) the flex?

[Bud Man]

I have recently become interested about flex. I built a tester and tested three skies. One interesting thing I noticed was what I perceive to be rebound. For example, as soon as the ski is loaded, it does not hold the tension. The tension settles a bit. I'm wondering if there is a correlation between little settling and quick rebound and more settling and less rebound.

Who else is flex testing and what are you finding? Do you preload the ski with a few pounds? And if yes, how much?

How much change in flex would indicate a ski is broken down?

And maybe the flex number doesn’t indicate it is broken down but the settling of the load that tells you it is broken down.

[skibug]

Now we're talking....where are those ski manufacturers and ski design engineers to chime in??  Please don't let us down and tell us it is a lot of empirical data derived throught trial and error.

[Skihack]

Not sure this applies to the new technology. I am very old school, wide body skis, no carbon and hand driving.

Just an example of how flex can affect one person's skiing. We tested fifty skis in one week. They were Jobe's. They were all from the same mold and had the exact tip and tail rocker, not much of a sweet spot. Some of the flexes were duplicates. They were blind to me the skier. I picked the two that I never missed 38 on. Turns out that the two I picked from 50 skis were the exact flex. They were 90 lbs in the mid section and 54 lbs in the tail. Now, these numbers are really low and can't be compared to the new skis. The Jobe's back then were wider from the forebody on down to the tail. But, all in all, this testing indicated to me that flex does play a very key role in ski design. I don't think today's skis can be made too soft though. I think tip and tail rocker is also a very key design element as well.

I do not know what you are skiing on, but for example, let's say you were skiing on an A1 of the same length as Will Asher's personal A1.

Suppose he let you ride his personal ski. I am fairly certain that you would ski better on his personal ski than yours.

The best thing to do in my opinion, is to try all of the skis out with the ride before you buy program and that way you get the ski that works best for YOU, not some ski you think will work best for you because some pro is riding it.

[jdarwin]

I believe D3 preloads 20 lbs.  Others may be more or less but it's a good idea to pre-load consistently.  The problem w/ our current method of flexing skis is that it does not measure torsional flex.  This can vary from ski to ski and often a ski can be breaking down and the current flex method will not detect it. 

[AdamCord]

I won't pretend to be any kind of flex guru, but I will say that we spend almost as much time dialing in flex after we've designed a ski as we do on the design itself. The right flex can totally make or break a ski. For production skis the standard across pretty much the whole industry is to flex in 4 spots, usually 17", 25", 33", and 41" from the tail. Most manufacturers preload the ski anywhere from 20-60lbs, then flex the ski .100". When we're dialing in a ski we generally measure flex at many more points and also measure the torsional flex, I'm not sure if other manufacturers do this or not. Andy spends more time figuring out flex than he does fin settings, and he's definitely the master at knowing what changes to make to flex. I'll be skiing a prototype and he will say something like "the ski's finishing 2-4 well, but imagine if you had 3 more pounds at 25"!". I say..."uh sure Andy, that sounds great..." :)

[skibug]

Sorry Adam; but, this is where it gets scary for me.  Empirical data is great for R&D.  What about consistancy across a line of skis, say all 67" Elites produced over a 6 month period from the same mold?  What is the allowable tolerance of flex and how much variance makes a difference.  Andy says 3 lbs added at one finite location could change the characteristics of the ski.  Is 3 lbs a lot by way of flex measurements or is it a "smidge"?  If 3 lbs is "smidge" then I say we are all OK; if it is a lot the we are all in more trouble.  I guess the only way I can compare it or think about it is in fin setup. If I am shooting for a fin length of 6.880 and can only really get 6.881 or 6.879; that is a "smidge".  6.870 or 6.890 is a lot.

I know this is why the pros may ride 15-20 skis before they pick one that works for them; but, maybe the rest of us hackers really don't need to worry about it.

[AdamCord]

For us regular guys, 3 lbs is no big deal. 10lbs however, you will definitely feel. The truth is, there were two main reasons why we decided to start building a ski using RTM. The first is we wanted to build a ski that was practically unbreakable and wouldn't break down, and the second is that we wanted consistent flex across all skis. With compression molding, it's common to see 10+lbs of variance from ski to ski. That's why you may jump on a new ski that's supposedly identical to your old one, and it doesn't feel the same. With RTM we never see more than 1-2lbs of variance.

 

You can often times make fin adjustments to try and help a ski that's flex isn't quite right, but it's always better to start with a ski that has a good flex.

[Horton]

Funny you should bring up the Elite.... I am going to start a thread about this tonight but.... I have 3 Elites that I need to sell at about 1/2 price. They are skis that were donated to the Diablo ProAm to raise funds for prize money. If you want a new ski for a killer price send me an email. Horton@BallOfSpray.com

[AdamCord]

Ooh you've got the Diablo ones?

Those skis are the 2011 layup!

[Horton]

Hmmm. I did not know that. Now there are only 2 and the price just went up.... Greg will never notice if I keep one...

[Steven]

Off topic but, What's the deal on the Quatro? Is that the new high end ski or an addition to the line up?

[Horton]

Second ski in Elite line

[Bud Man]

Adam,

Please elaborate on preload and why you preload.

Example:

1.       Ski goes in at 44†from tail

2.       raise jack so that ski comes in contact to two rods

3.       zero out scale

4.       raise jack to load ski to 20 lbs

5.       zero out dial indicator

Do you also zero out the scale?

6.       Raise jack 0.1 (one tenth of an inch)

If I zeroed scale after step 5 and got a reading of 130 lbs after step 6, would the flex at 44†be 130 or 150?

If I did NOT zero the scale after step 5 and got a reading 150 after step 6, would 150 be the flex at 44�

[AdamCord]

Bud-

You're correct that we zero the scale and the dial indicator after preloading. This is why you can't really compare flex numbers without knowing what the preload number is. The reason we preload is because it's much more accurate than trying to get the jack to juuuuust touch the ski without loading it, and then going from there.

[ktm300]

What flex characteristics does the onside turn like? v. the offside? My onside turn sucks and has for years. I had a ski this year that gave me the best onside turn but, it made a too big turn on the offside. Tried everything to get it to work to no avail. On a ski now that wants to go straight at the onside upon releasing from the handle. Exiting the second wake, I am early and in good position. Edge change and straight at the ball. The flex numbers on the great onside ski were 71.5, 107, 138.5, 170. Current ski I haven't had a chance to flex. Thanks.

[Horton]

Way more than flex controls how a ski feels/works. Have you thought about golf?

[ktm300]

Thanks Horton. Golf not for me. I should have been more specific. I could order 10 (name the ski) and they all feel different. Some turn the onside better. Since they all came out of the same mold, I assumed that it is flex that causes the difference. My question is what change in flex benefits one side v. the other. Goodes neutral and SL come out of the same mold. It is the flex that is different. What specifically? Thanks again for your help.

[Bud Man]

Adam,Thank you for your response.So I zero scale after preloading 20lbs. and then raised jack 0.1†and get a reading of 130 lbs, would the flex at that given location be 130 or 150?Thank you.

Bud