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Gotama 07/08 Center Marks - Huh? - Page 3

post #61 of 70

brewski - before you drill more holes into your skis in a "guess" regarding where your bindings should be mounted I recommend you take my advice to heart and really figure out where you should most likely be on the ski based on a BoF mount point.  It's doubtful the "guys" in the shop know anything about BoF mounts - it's just not common knowledge these days thanks to the manufacturers adoption of the boot midsole mark.

 

The difference between 1cm and 2cm is huge in binding mounts.  I know 10mm doesn't sound like much, but I've been amazed at how much change you actually get.  I can even feel 5mm, but generally I won't remount for a 5mm adjustment - 10mm is a whole different story.

post #62 of 70

Noodler,

 

In a totally unscientific exercise while pressed for time yesterday I measured CRS on my 2009 176 goats to be at 747mm.  I then tried to approximate my BoF by removing the liner and placing my foot in the shell with equal room at toe and heel and had my son mark my boot.  I then put the liner back in, put the boot on and tapped the boot to again approximate BoF and marked again.  The result was similar to within ~5mm.  When I clicked my boot back into my ski it appears as though my BoF is 1cm behind my CRS mark.  My boot is a 27.5 Rossi Zenith 120 pro with 315 bsl and the shop mounted my Sally Z12 Ti bindings -1.5cm from the True Center mark (front line) on the top sheet.

 

Before you flame me for my less than precise BoF measurement let me reiterate that this was just to approximate given limited time.  Given this thread and accounting for my imprecise measurement method I was surprised to find my BoF behind CRS given the mounting point.  In your estimation did I totally screw up in my rush to measure?  Edit: I haven't skied them yet since I just had them mounted last week and am wondering if I should even bother before having the shop move them back.


Edited by RMRC - 3/3/2009 at 02:47 pm


Edited by RMRC - 3/3/2009 at 02:50 pm
post #63 of 70

RMRC - heck no I won't flame you.  I commend you for the effort and for acknowledging that maybe there's really something to this and something you should be concerned with.

 

The hardest part in the process is determining your BoF adjustment value (the distance from the boot midsole mark to your BoF).  I've found that you can double-check your work by simply dividing the length of your foot in half (measured when on your footbed under full weight) and placing that mark on your foot.  Then check the distance from that mark to the BoF position found by standing on your toes.  As long as you have a performance fit in your shell (1 finger or less, < 0.5") then you should find that the distance from that mark to your BoF mark is closely aligned with a value found through boot tapping.

post #64 of 70

 

Quote:
Originally Posted by RMRC View Post

 

Before you flame me for my less than precise BoF measurement let me reiterate that this was just to approximate given limited time.  Given this thread and accounting for my imprecise measurement method I was surprised to find my BoF behind CRS given the mounting point.  In your estimation did I totally screw up in my rush to measure?  Edit: I haven't skied them yet since I just had them mounted last week and am wondering if I should even bother before having the shop move them back.

 

Clearly you should ski them first, but if you had to error in either direction you are much better off erroring to the rear than forward.  You can definitely go overboard with a too far forward mount and pretty much make a ski unskiable.  Conversely, a rearward mount will make the ski harder to turn while also making it feel more stable, but I don't think it will become unskiable unless you went ridiculously far back towards the tail.  I think you could really screw up a forward mount by going as little as 10mm too far, but being 10mm, 20mm, maybe even 30mm too far rearward will not send your skiing to the trash can.

post #65 of 70

Noodler, thanks for the responses.  Very helpful.  Fully realizing it comes down to personal preference and having read this entire thread, I'm curious if you (or anyone else) believe there is an ideal BoF location relative to the CRS?  It seems +1 from the boot center line is most liked/accepted but this would put my BoF roughly -3.5cm from CRS.  And the reason I ask this is should I find I'm mounted too far forward now I only want to drill these skis one more time and be done.  Then again +1cm given my basically "average" BSL would probably yield a good result.  Long way to arriving at SJ's advice .

post #66 of 70

BoF mount position is merely a starting place and will generally work well when a skis flex pattern (when weighted at the CRS) is fairly symmetrical.  The adjustments to this position make sense when compensating for the ski's flex pattern.  A stiffer tail and you may feel better more forward, stiffer shovel - more back.  

 

I think that what's going on here is that when we pressure a ski from it's middle we can best utilize the arc formed by both the tip and the tail.  However, skiing style definitely plays into this and some people may not actually feel most comfortable with equal pressure hitting both ends of the ski.  That's why I'm more comfortable going with BoF as my starting point rather than the "collective knowledge" of other skiers' experience on a ski.  If you've skied with someone and you're familiar with their style, preferences, body stature, etc. then you can put more stock in their opinion on gear issues.  Over the Internet you just don't know who you're dealing with (especially with guys who call themselves "Noodler" online - why would you trust a noodler? ).

 

 

post #67 of 70

Wow - my last post just gave me an idea.  Let's totally tech/geek out for a moment...

 

Take a ski and find the tip and tail contact points (the ends of the CRS).  Position the ski on top of two saw horses (or similar) with a fairly thin contact point used on the top of each that will be aligned with the contact points.  Then hang a good amount of weight from the middle to make the ski bend.

 

 

Move the weight along the length of the ski until you find the position where the weight is closest to the floor (the red line in the diagram) thus finding the ski's "flex middle" - the point where the ski reaches the greatest amount of full flex.  You could then compare this point to the CRS and make some new conclusion about the binding mount position based not only on BoF over CRS, but also taking into account the ski's flex pattern.

 

Am I totally crazy?  Am I missing something?

post #68 of 70

Noodler- Thanks for the input. I plan on figuring my BoF out later tonight or sometime this week. Didn't mean to make ya think I didn't care about what you said.

post #69 of 70

Well I put three days on the Goats last weekend including a Sunday at Sugarbowl when we awoke to 2-3ft of fresh relatively light powder.  Mounted 1cm back of True Center Line made for a lively quicker than expected turning ski (given the width) and may work if the ski is to be used as a true all mountain ski but I bought the Goat as my powder/recent snow ski.  Mounted further forward there was just too much tip dive.  So at the end of the day I'm moving the mount back to The Boot Line +1cm as is widely recommended.  For those who intend to use the ski for powder (and assuming you have an avg bsl of ~315) just do yourself a favor and mount +1cm from the back line as SJ and many others who have experimented with mounting points rec and be done with it.  My $0.02.

post #70 of 70

 

Quote:
Originally Posted by Noodler View Post

  Let's totally tech/geek out for a moment...

  Always up for that. 

 

 

 You could then compare this point to the CRS and make some new conclusion about the binding mount position based not only on BoF over CRS, but also taking into account the ski's flex pattern. OK, but what conclusion? Should the BoF be brought closer to flex midpoint? 

 

Am I totally crazy?  Am I missing something? No, but two issues. First, I spent some timetwo years ago talking with a Prior designer about mount positions vis-a-vs sidecut, and he seemed to feel that the "center of the natural turning radius" was the real issue rather than flex. Second, if you look at the "FRI FLYT" flex curves floating around the web (including Epic) produced from a rig something like yours, many look nothing like your diagram. (Surprised me too.) A lot of twins have a "plateau" with no clear peak of stiffness, and then radically softer tips and tails; many skis are actually stiffest way away from the CRS, but in either direction depending; and relatively few skis of any type have a nice bell curve centered near or on the CRS. So yes, you could hang a weight and make any ski bend, but not sure what that would mean in terms of actual ski flex onslope. 

 

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