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did I go too far back?

post #1 of 22
Thread Starter 
When i bought my mantra's (177cm) last season i had them mounted 1.5cm back, since they are my powder ski. This year they needed to be adjusted to my new, smaller boots. I hat the shop only move the toe piece pack on my rossi pivot 140's. This move resulted in another 2cm movement back. So now im something like 3-3.5cm back from the center mark. Am i going to be noticibly further back? Will groomers be more dificult and powder be better? Did i screw up?
post #2 of 22
You'll probably experience some tip wandering and an increased tendency for the tail to come out from under you when you get real far back. I would've mounted them up at the standard midsole mark both times for powder and only moved them forward for park.
post #3 of 22
agree with takecontrol. ^^^^^^ I can understand why some freestylers mount a bit forward, but I don't understand the recent craze with mounting bindings behind the center line. pow skis are designed for pow and the midsole line on the ski reflects that.
also, you may have trouble getting the tip to initiate. If you are 3 centimeters back, a remount would not hurt the skis (only the resale value if you plan on selling--- which you should NEVER do--- especially with a pair of mantras.)
post #4 of 22
1) where is the ski's mounting mark from the center of the skis running surface?

2)what did you think of the ski's hard snow performance last season? how about powder?

3) measure from the back edge of the sole of you boot to where the ball of your foot is in the boot? do this as best you can for both boots. since your heal piece is in the same place, you can use these numbers to see where you are really standing on the ski, you may not be as far back as you think.
post #5 of 22
Quote:
Originally Posted by samurai View Post
agree with takecontrol. ^^^^^^ I can understand why some freestylers mount a bit forward, but I don't understand the recent craze with mounting bindings behind the center line. pow skis are designed for pow and the midsole line on the ski reflects that.
also, you may have trouble getting the tip to initiate. If you are 3 centimeters back, a remount would not hurt the skis (only the resale value if you plan on selling--- which you should NEVER do--- especially with a pair of mantras.)

midsole marks are not designed into the ski. there are a number of threads here that discuss this topic from a techanical standpoint. the search tearms "bof," "crs," and "Campbell," will turn up some interesting reading.
post #6 of 22
The Mantra mounting line was biased forward in the 05/06 model, and reports from numerous skiers continue to recommend 1.5 cm behind the line. The ski has a LOT of tail when skied at the factory line, and stability suffers at very high speeds and in some difficult conditions. the soft tip seems to keep the Mantra from diving in the boot center position, but larger or faster skiers had a sense of going over the handlebars as speed built.

I would suggest that the -1.5 mounting point is fine based on the feedback I have seen and my experience from the 05-06 model. Ski it and judge for yourself. Obviously if the mounting is done, its best to give it a try before making any changes. I think you will find you can maintain a more forward weight postion in powder without instability, and this is a stronger position, than if you had to lean back to keep from diving.

What is unusual is that you doubled the negative mounting point by changing boots. You must have been terribly oversized before, to have moved 1.5 to 2 cm more off center. Do a search on the Ball of Foot (BOF) mounting on skis and do some measurements to see where you stand from that position. I recommend you ski them, but even if you need to move the bindings, the ski is plenty durable to handle the second mount as long as the holes are separated.
post #7 of 22
Quote:
Originally Posted by monkeyboy View Post
midsole marks are not designed into the ski.
I'm a fairly educated skier, but I have no idea what this means. I did a search and discovered some people seeking advice on BOF mounting, which I first did about ten years ago, but I have never seen a factory ski without a midsole mark on it. where am I lost here?
post #8 of 22
Thread Starter 
yeah, i was terribly oversized. This is my first set of new boots that i actually had fit. In years past i would go to the used eqipt sale and get some boots that were comfortable. No one had to time to sit with me then to check the fit. I went from a 28 shell to a 26
post #9 of 22
Quote:
Originally Posted by samurai View Post
I'm a fairly educated skier, but I have no idea what this means. I did a search and discovered some people seeking advice on BOF mounting, which I first did about ten years ago, but I have never seen a factory ski without a midsole mark on it. where am I lost here?
Meaning that engineers have nothing to do with where that mark is drawn on the ski. It is determined by testing, but that means that the marks placement will depend on, amoung other things, WHO tests the skis. Further, its not clear what manfuactueres are trying to achive with the placement of this mark in terms of performacne. The purpose of this mark is to standartize the mounting process, first to make life easier for shops, and second to make the skis more consistant, i.e., the skis will perform the same no matter what shop mounted them.
post #10 of 22
CR:

Out of curiosity, where do you have your Mantras mounted?

Did you go back from the factory line or did you do the whole BOF assessment?

I've got a few pairs of skis awaiting to be mounted (finally decided on bindings!) and in the past I've usually gone with the factory line/where they were mounted on the demos I rode. After perusing all of the threads, I'm second-guessing (ugh!) on whether to go through the whole BOF routine that Noodler lays out in another thread or just stick with the factory line.

Secondary question, where/how can one obtain the mounting point for certain skis? I have some Titan 8's and the mark isn't readily apparant. I know that you hooked some other Bears up with factory mounting line measurments for Mantras, which is why I'm tossing the question out there.
post #11 of 22
I remember the Rossi 9X's and Volkl G41's used a specific shell size to determine that line on the ski. the rossi was like a 28 shell for a (205?) and the volkl was a 27 for their 188. Meaning the midsole line on the boot matched the ski's line which put the BOF relatively close to the ski's center-balance-point.
I remember as I had to mount a bit forward to accommodate my small feet. I called the factory and they told me exactly how many centimeters from the tail the ski's center-balance-point was. it was engineered. It's not any more difficult for a ski manufacturer to think about that line mathmatically than it is to go out and test it a number of times and draw a few different specs and ideas about where it should maybe go.

I do believe many ski manufacturers probably throw a rough guestimate out there to keep the skis consistent and may not use AutoCad software like Volkl does (or did 10 years ago), but that does NOT mean that most people should mount anything +2 or -1 or whatever based on someone's review. Foot size/BOF is the second main factor after knowing exactly where the ski's center-balance-point is.
If people really are concerned about where to mount, please take the time and do it right. It's not about reading 10 reviews and finding your mounting spot. It's all about matching your BOF with the ski's center-blance-point. And it's not nearly as difficult as many assume if it is broken down and simplified in that manner.
personally i stick with the factory line or fade forward as I do have small feet. skis really are forgiving these days and much easier to ski than anything 10 years ago when I actually stressed about it during the progression from straight skis into carvers. Now they act like remote controls... all you have to do is be generally center on your skis and think and they will turn. No more insane tip initiation by squeezing your shin into the front of the boot, then rocking back to ride the tail out. (actually many WC racers still do this... see other threads about Ligety's hips back)
but if you are a WC racer, you probably have the manufacturer telling you exactly where the center-balance-point is.
anyway, make a phone call, get out your tape-measure, find your BOF, mark, drill. go skiing.
or... find your ski with a demo binding and experiment.
post #12 of 22
Quote:
Originally Posted by samurai View Post
...that does NOT mean that most people should mount anything +2 or -1 or whatever based on someone's review. Foot size/BOF is the second main factor after knowing exactly where the ski's center-balance-point is.
If people really are concerned about where to mount, please take the time and do it right. It's not about reading 10 reviews and finding your mounting spot. It's all about matching your BOF with the ski's center-blance-point. And it's not nearly as difficult as many assume if it is broken down and simplified in that manner.
Not based on random reviews...

More and more skis, especially twins, are being marked with a range. You get to pick where within the range to mount based on preference, your size, etc. The Mantra should probably be marked in this way.

If you poked around enough, you might find that the 1 - 1.5 back suggestion for certain riders and uses just might be endorsed by your local Volkl tech type folks. One of my kids just had his Mantras mounted 1 back - after our favorite shop checked with their connections at Volkl. The other has been skiing his 1.5 back for a year based on comments at TGR and here. He's got railflex bindings & could move to the mark - if he wanted to...

As for the BOF common wisdom, this might deserve a thread of its own - but I'm pretty skeptical of the whole BOF on center of "running surface" thing at this point. Today's skis vary greatly in any number of parameters. The nature and placement of sidecut. Degree of taper (some "conventionally shaped" powder skis today can have as much as 25 or 30mm of taper...). Flex characteristics. Etc. My strong suspicion is that the BOF on center of running surface is an old carryover that today is more superstition than justified by any engineering reality. I'd love it of someone with appropriate engineering knowledge could explain to me why my intuition on this is wrong...
post #13 of 22
Your intuition isn't wrong about trusting the engineers. They really do know what they are doing. and trusting the lines they put on the ski is a good idea. yes, many skis do have a Freestyle mounting point (for switch yada-yada) and a freeride mounting point which is considered by many to be the standard.

also you commented on contacting volkl techs and learning to mount 1 back. That is exactly what I like to hear.

Your ideas about BOF being a carry-over from the previous generation of skis could be spot on. as I mentioned before, skis today are way more forgiving than previous generations and I don't even worrry about it anymore.
I was posting here in hopes of saving a skier who happened to have larger (not smaller) feet yet decided to mount +2 based on some vague opinion.
post #14 of 22
Quote:
Originally Posted by samurai View Post
I remember as I had to mount a bit forward to accommodate my small feet. I called the factory and they told me exactly how many centimeters from the tail the ski's center-balance-point was. it was engineered.

The exact center-balance point is determined empirically, not engineered.
post #15 of 22
Quote:
Originally Posted by samurai View Post
I remember the Rossi 9X's and Volkl G41's used a specific shell size to determine that line on the ski. the rossi was like a 28 shell for a (205?) and the volkl was a 27 for their 188. Meaning the midsole line on the boot matched the ski's line which put the BOF relatively close to the ski's center-balance-point.
I remember as I had to mount a bit forward to accommodate my small feet. I called the factory and they told me exactly how many centimeters from the tail the ski's center-balance-point was. it was engineered. It's not any more difficult for a ski manufacturer to think about that line mathmatically than it is to go out and test it a number of times and draw a few different specs and ideas about where it should maybe go.

I do believe many ski manufacturers probably throw a rough guestimate out there to keep the skis consistent and may not use AutoCad software like Volkl does (or did 10 years ago), but that does NOT mean that most people should mount anything +2 or -1 or whatever based on someone's review. Foot size/BOF is the second main factor after knowing exactly where the ski's center-balance-point is.
If people really are concerned about where to mount, please take the time and do it right. It's not about reading 10 reviews and finding your mounting spot. It's all about matching your BOF with the ski's center-blance-point. And it's not nearly as difficult as many assume if it is broken down and simplified in that manner.
personally i stick with the factory line or fade forward as I do have small feet. skis really are forgiving these days and much easier to ski than anything 10 years ago when I actually stressed about it during the progression from straight skis into carvers. Now they act like remote controls... all you have to do is be generally center on your skis and think and they will turn. No more insane tip initiation by squeezing your shin into the front of the boot, then rocking back to ride the tail out. (actually many WC racers still do this... see other threads about Ligety's hips back)
but if you are a WC racer, you probably have the manufacturer telling you exactly where the center-balance-point is.
anyway, make a phone call, get out your tape-measure, find your BOF, mark, drill. go skiing.
or... find your ski with a demo binding and experiment.
Dou you actually read the other posts in a thread, or do you just rant? Go back and read my first post. I suggest he should evaluate how the skis performed the previous year, and then figure out just where he is really standing on the skis relative to last year. How do you infer that I am recomading that any specific mounting point is best for most people?
post #16 of 22
Quote:
Originally Posted by monkeyboy View Post
The exact center-balance point is determined empirically, not engineered.
I understood Volkl engineered it using autocad, several years ago. I'm sure they tested their hypothesis and came to a conclusion which would result then in an empirical consensus. (not trying to be a smart**s)

can we agree that the center-balance point is known by the factory? and this is NOT what is marked on the ski?
Can we agree that the line (or lines) on the ski is representative of a given shell size (according to the skier who tested it?)
can we agree that everyone's BOF will be a different distance from that line?
can we agree that one man's +2 is another man's +3? (assuming they have different sized feet by roughly 1-2 cm.)

can we agree that mounting on the line is generally accepted as a good idea?
can I shut up now?
post #17 of 22
Quote:
Originally Posted by samurai View Post
I understood Volkl engineered it using autocad, several years ago. I'm sure they tested their hypothesis and came to a conclusion which would result then in an empirical consensus. (not trying to be a smart**s)

can we agree that the center-balance point is known by the factory? and this is NOT what is marked on the ski?
Can we agree that the line (or lines) on the ski is representative of a given shell size (according to the skier who tested it?)
can we agree that everyone's BOF will be a different distance from that line?
can we agree that one man's +2 is another man's +3? (assuming they have different sized feet by roughly 1-2 cm.)

can we agree that mounting on the line is generally accepted as a good idea?
can I shut up now?
This was exactly my point, except the mounting on the line thing, I've almost never been on the line, but everone needs to figure out what is best spot individualy. The line is bad for the same reason as following random advice is bad.
post #18 of 22
Quote:
Originally Posted by monkeyboy View Post
Dou you actually read the other posts in a thread, or do you just rant? Go back and read my first post. I suggest he should evaluate how the skis performed the previous year, and then figure out just where he is really standing on the skis relative to last year. How do you infer that I am recomading that any specific mounting point is best for most people?
I'm sorry... I never disagreed with you personally. Nor did I say that you RECOMAD that any specific mounting point is best for most people. I believe you took a very unneccesary offense to my post.

is my tone implying an argument? I'm sorry...

I'm going to leave this thread now.
post #19 of 22
Quote:
Originally Posted by monkeyboy View Post
This was exactly my point, except the mounting on the line thing, I've almost never been on the line, but everone needs to figure out what is best spot individualy. The line is bad for the same reason as following random advice is bad.
To my speculation above - I suspect that on average, most people are far, far better off on the line than fooling around with bof and running surfaces. And certainly better off staying in the suggested range if there is one on the ski or suggested relative to the line by the manufacturer. Especially since I suspect, as noted above, that for many modern design skis the bof at center of running surface approach might well yield sub-optimal results. I seem to remember some critical commentary about Atomic lines being way far back. Maybe there's a reason - or do people think Atomic has historically wanted everyone to get less out of their skis?

Also, if you have real knowledge that the line for most skis is determined empirically rather than designed, I'd be curious to hear more about it. Given the engineering tools available, I'd expect the line to be "engineered" more often than not (again, with an expected range in some cases)...
post #20 of 22
Quote:
Originally Posted by spindrift View Post
I seem to remember some critical commentary about Atomic lines being way far back. Maybe there's a reason - or do people think Atomic has historically wanted everyone to get less out of their skis?
Best way to find out is to get pair of atomics (or two) and try.

Quote:
Originally Posted by spindrift
Also, if you have real knowledge that the line for most skis is determined empirically rather than designed, I'd be curious to hear more about it. Given the engineering tools available, I'd expect the line to be "engineered" more often than not (again, with an expected range in some cases)...
That "expected range" is quite large. Determing a ski's "sweet spot" numerically requires more than a first order stress/srrain analysis. A larger number properties factor into the calcualtion of the ski's sweet spot. Since an expert skier can easily feel a centimeter displacement form the sweet spot the only way to determine this spot precisely is experimentaly.
post #21 of 22
Do you have industry design knowledge - or are you speculating? Not picking a fight. I'm genuinely curious...
post #22 of 22
Quote:
Originally Posted by spindrift View Post
Do you have industry design knowledge - or are you speculating? Not picking a fight. I'm genuinely curious...
I've never worked as a ski engineer, but a ski is a "simply" a composite laminate panel. The key design parameter that defines a ski beyond this is the sidecut, and even ingnoring that still leaves a difficult problem. It's not that it can't be done with sufficent precision, it's more that is not worth it.

I have quite a bit of experience writing numerical codes, including for this type of problem, and I have Catia 5 (autocad is for whimps) running on the computer I'm posting this from, as well as more than a few of those other "engineering tools" you spoke of.
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