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krick

In the parking lot (formerly "At the base lodge")
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A couple of questions that I've been pondering as I've been mounting various skis recently:

1. What is the minimum amount of fore/aft deviation necessary to have a discernible effect on ski performance or character? Asked another way, if you start with the factory recommended mount position as the baseline and move fore or aft of that in 1mm increments, at what point will the change in position have a discernible effect? I realize that there are both objective and subjective elements to this and that it will vary from ski to ski taking into account shape, design and length, but I'm curious because a lot of people state their preferred mount points on various skis in .5cm increments, which would suggest that at least those people can feel .5cm differences in position.

2. Related to the first question, what is the acceptable installation tolerance for a binding mount that you are having done or being asked to do - i.e., if a shop is asked to mount a binding at a particular position, how much deviation from that is acceptable? On the one hand, if you can tell differences down to .5cm, then anything more than perhaps a mm would arguably be unacceptable. On the other hand, expecting precision down to 1mm (or even 5mm) on a 1700-1900mm ski would arguably be unreasonable.

Personally, having spent a couple years using demo bindings on my skis and constantly adjusting the positions, I'm certain that I can't tell a .5cm difference and I'm not sure that I can reliably tell a 1 cm difference either, but at 1.5-2cm it starts to become really noticeable.

Thoughts?
 

Eleeski

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You answered your own question when you said you couldn't feel a .5cm difference. Note that BSLs can vary by .5cm between brands for the same foot. If you get new boots you might have ski changes if you are super sensitive. So really, the tolerances can be fairly wide.

Mount to half the tolerance +- 3 mm should be good. A little tighter from ski to ski in the pair but it's hard to see, measure or notice a couple mm over the length of a ski.

Conditions, ski tune and how you feel affect your skiing more than binding placement.

With that said, I try to put demo bindings on all my skis and enjoy screwing around with the settings (in 1cm minimum changes). I've really changed the ski performance to my liking with a couple cm change over stock on a couple skis. Once I settle in on a placement, I stick there and spend my effort in the tune. But I enjoy the testing process.

Eric
 

Utahski

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You won't feel 1mm, but definitely feel 5mm (1/2cm), and 1cm even more. I'm mostly on GS skis of some sort and use the older Atomic race bindings / plates for just that reason.....to fool with boot position. Some skis feel best centered, some are better one notch / 7mm forward of center, and occasionally all the way / 14mm forward feels just right. Never know. SS can tell you about how center points can differ with different skis. With shorter slalom or all terrain skis or something with a lot of sidecut, mounting on the center point works fine for me. About installation tolerance, that depends on who's mounting them.
 

Dakine

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I moved the bindings 1 cm back on my 18m Heros and it made them ski very different.
On the line they felt powerful but vague and dangerous, 1 cm aft and they feel right under foot.
 

BoofHead

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I have Tyrolia Railflex bindings on a couple of pair of skis. +/- 1.5.
Each position feels different. As an example, I mounted the +1.5 on the centreline of my older Mantras giving me up to -3 behind the line.
I have them on the line nearly all the time but before I started skiing on more appropriate skis in Japan, I would move them back the full 3 for powder; -1.5 for between storms.
 

PTskier

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Head/Tyrolia Railflex here also. The size adjustment notches are 4 mm apart. I can't feel 4 mm of change. I can feel 8 mm forward...better tip bite on my Head Supershape i.Rally.
 
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krick

In the parking lot (formerly "At the base lodge")
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I should have been clearer in my post - I wasn't actually asking about what I would or would not feel (I do know the answer to that), but rather what other people think they can feel and what they think is an acceptable tolerance range for a mount.

You won't feel 1mm, but definitely feel 5mm (1/2cm). . .About installation tolerance, that depends on who's mounting them.

How about both ways - if you were the customer and you were paying a shop to mount brand new skis and binding on a designated line and the mount ended up being off by 5mm, would you be ok with that? And the other way, what if you were the shop owner and a customer complained about a mount being off by 5mm from the requested position?
 

Eleeski

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If I'm buying, +- 2mm. If I'm selling, +-3mm. If I'm skiing, I'm still going to do well at +-5mm. If I'm racing, I'm freaked out by anything more than +-1mm but it will take +-3mm to actually change my time.

I've mounted lots of bindings. I don't have the tools or skills to do better than +-3mm. I still like my mounts.

Missing a mark by 5mm is a pretty serious miss. Try the ski to see how it works - it is likely to be fine. Might be better. But if you did the work to dial in a spec, a quality shop should be closer than a miss of 5mm. A crappy shop, 5mm ain't bad.

Disclaimer, I don't run a shop. But I do repair a lot of waterskis for the college teams. Fresh mounts are different from repair remounts - in how they are viewed by the user. Factory mounts aren't always perfect...

Eric
 

crgildart

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Depends on the ski.. The softer the flex, the less you'll feel a 1cm difference. The stiffer the ski, the more you will feel different bite at different mount points. A very soft ski will be too noodly to tell much.
 

Utahski

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You're being kind of vague about this. You don't mention the ski or if it's forward / back. The mount shouldn't be off by 5mm. Doesn't sound like a lot, only 3/16", but still it should be closer than that. I'd definitely talk to the shop about it. However, short of putting plates on there and re-mounting there's not much can be done about 5mm......it takes 10mm/ 1cm between hole centers before they don't infringe on each other. As has been mentioned it depends on the ski, but also just as much on how they feel to you. I have the option of direct comparison by changing things on the hill. If yours are new with no way of comparing, you won't know til you try them, they may feel just right.
 
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krick

In the parking lot (formerly "At the base lodge")
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I'm not sure how I'm being vague, but I'd be happy to clarify. The question to you was a hypothetical one and I didn't specify the ski or whether the deviation was fore or aft because I didn't think those mattered for purposes of the hypothetical I posed to you. Are you saying that whether you would be ok with it or not as the customer, or how you would handle a customer complaint as the shop, would depend on the ski and whether the deviation was fore or aft?

You're being kind of vague about this.
 

François Pugh

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I've noticed significant effect at 6 mm on ice with GS skis.

Also, my boots vary in length from 315 to 309 mm and the toe piece is fixed, so a 3 mm difference between boot pairs, and I notice a big difference, but most of that could be chalked up to the shorter boots also being better set up and more responsive boots.

If I specified a mount at X mm and I got X plus or minus 3 mm, I would not complain.
 

flying_j

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Head/Tyrolia Railflex here also. The size adjustment notches are 4 mm apart. I can't feel 4 mm of change. I can feel 8 mm forward...better tip bite on my Head Supershape i.Rally.

I have these very same Head Rally skis with the PRX12 binding. :)

First day out on them, started with the nominal position for my bsl. Mounted center, the tip just does not want to bite on these skis. Took a few runs, then decided to adjust forward the 8 mm that @PTskier mentions above. Wow, now those tips really bite. Effortless to engage. In fact, that's all it wants to do! That, plus a feeling that there's just 'too much' tail, too. So, I moved it 4 mm back to the midpoint between those two settings, and for me that is the sweet spot on this ski. I can stay centered over them easily, tips engage well and the skis just rail through turns and release when I want them to.

So, for me, on these skis, I can tell a difference of 4 mm.

I currently have a pair of Bushwackers that I mounted the bindings on. I'm within 3 mm of the center mark on them. Different tool for a different job. Never gave it a second thought.
 

karlo

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Depends on the ski.. The softer the flex, the less you'll feel a 1cm difference. The stiffer the ski, the more you will feel different bite at different mount points. A very soft ski will be too noodly to tell much.

I have these very same Head Rally skis with the PRX12 binding. :)

First day out on them, started with the nominal position for my bsl. Mounted center, the tip just does not want to bite on these skis. Took a few runs, then decided to adjust forward the 8 mm that @PTskier mentions above. Wow, now those tips really bite. Effortless to engage. In fact, that's all it wants to do! That, plus a feeling that there's just 'too much' tail, too. So, I moved it 4 mm back to the midpoint between those two settings, and for me that is the sweet spot on this ski. I can stay centered over them easily, tips engage well and the skis just rail through turns and release when I want them to.

So, for me, on these skis, I can tell a difference of 4 mm.

I currently have a pair of Bushwackers that I mounted the bindings on. I'm within 3 mm of the center mark on them. Different tool for a different job. Never gave it a second thought.

@flying_j, the Rally’s are stiffer than the Bushwackers??
 

David

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If I'm buying, +- 2mm. If I'm selling, +-3mm. If I'm skiing, I'm still going to do well at +-5mm. If I'm racing, I'm freaked out by anything more than +-1mm but it will take +-3mm to actually change my time.

I've mounted lots of bindings. I don't have the tools or skills to do better than +-3mm. I still like my mounts.

Missing a mark by 5mm is a pretty serious miss. Try the ski to see how it works - it is likely to be fine. Might be better. But if you did the work to dial in a spec, a quality shop should be closer than a miss of 5mm. A crappy shop, 5mm ain't bad.

Disclaimer, I don't run a shop. But I do repair a lot of waterskis for the college teams. Fresh mounts are different from repair remounts - in how they are viewed by the user. Factory mounts aren't always perfect...

Eric
Now you have wondering about the variance between each ski of the same pair?
 

Eleeski

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A couple of my worst mounts look uneven by 3 mm. I'm not sure I can actually measure a whole lot better with my shop tools and the variability of the skis. Do I measure from the tip, the tail or the mark on the ski? Couldn't tell the difference skiing.

I did a wax one ski, no wax on the other. I skied fine and didn't notice a difference after a run or two - but maybe that's because wax is overrated.

I don't normally keep track of right and left skis and can't feel the difference.

I do have one real hip and one titanium one so maybe my skeletal differences overshadow any minor ski differences.

There are many far more important variables that affect how I ski than precision mounts.

Eric
 

Doug Briggs

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You can never trust the 'center of boot' marks on skis to be the same. I've seen differences of well over a cm between a left and right ski. I ALWAYS measure from the tail to the mark. If there is more than a MM of difference, I adjust one, the other or both so that the bindings are mounted the same distance from the tail.
 

ski otter 2

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I use Marker Schizos a lot on fatter skis, and PRDs, demos or system bindings on many narrower skis. I prefer Marker Schizo/demo bindings, because the mount point/boot fit can be screw adjusted by clicks of less than 1 mm, compared to, say, the four mm slot adjustments of the PRDs. I like the Atomic/Salomon race bindings also because they are readily adjustable at both toe and heel, rather than just the heel or neither without binding screw removal. So I've gotten to experiment a lot with different skis and bindings. To me, from experience, it's a big deal.

From now on, I'll measure from the tail to check and compare bindings mounts from ski to ski, rather than just go by the line. I've usually forgotten to do this. Thanks, @Doug Briggs. I'll probably do that soon with problem mounts I've seemed to have, and still have, around this issue.

I've often gotten skis back with 2-4 mm differences on mounting points from what I've asked for, and even from ski to ski in the same pair, seemingly, even when the bindings were Schizos (a real hassle to keep track of which ski is which, and which skis are so off among my schizo-mounted skis - gotta use a piece of tape on that ski to keep track). Often, I don't go back (at least for tech work) to the shops that did that, especially if they've made other mistakes also in the past and shined me on. I figure that if they made that mistake so casually, they'll probably just think I'm nuts for caring about such differences. Similarly, if both skis are off the recommended mount point or point agreed to beforehand between me and the mount shop, by more than 2 mm., I'm going to ask about it if I have a great relationship with the folks in that shop especially, and may or may not go back (again, for tech work). Often, the folks up front who sell the skis and talk to the public are not the ones who work on the skis or determine repair/tech protocols for that shop.

For me, a difference greater than 1/4th a cm or so is noticeable, very. That's 2.5 mm. On some skis/binding setups, that difference while noticeable is not as big a deal as it is on others. On a few skis, it is a very big deal (on the V-Werks 184 Katanas, for me, for example). For me, this ski tail dives in powder at farther back than about -1.25 cm. It's as if the tail becomes a rudder, actually. At -1.5, this dive becomes like dragging a rudder down the mountain, in many powder conditions. At -1.25, again, the problem becomes intermittant: repeatedly here and there as one goes. But at -1 or less, the problem goes away completely - not once over many years. At the other end, on the same ski, from -0.5 to -0.9 or so, things are great (best at closer to -1 cm., in terms of feel). But at zero or farther forward, for me, this 184 length will fold slightly (hesitation sudden slow down) on thicker or deeper drifts or some powder transitions. At +0.5 and farther forward, that problem becomes more common, and worse. At +1 and farther forward, for me, that 184 Katana becomes a real mess, almost coming to a stop at times, requiring a complete change in how I'm skiing. And yet at the right mount points (different for every size and style skier, I'd imagine), this is one of my favorite powder/crud charger skis.

Many other skis have much wider mount point ranges before the changes become so drastic, but still vary quite a bit.

.
 
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Ross Biff

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You can never trust the 'center of boot' marks on skis to be the same. I've seen differences of well over a cm between a left and right ski. I ALWAYS measure from the tail to the mark. If there is more than a MM of difference, I adjust one, the other or both so that the bindings are mounted the same distance from the tail.
I find it annoying that a reference mark on a top sheet for something as crucial as a binding mount can be off from ski to ski so, yep, measure up! Curious as to were you decide the mount point should be when there is a discrepancy.
 

Doug Briggs

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I find it annoying that a reference mark on a top sheet for something as crucial as a binding mount can be off from ski to ski so, yep, measure up! Curious as to were you decide the mount point should be when there is a discrepancy.
If its less than a cm difference, I'll usually split the difference. If I can look up the recommended mount point, I'll use that. When in doubt, I'll consider the use of the ski. Carver, forward bias. Powder, aft bias. I also call customers to discuss it with them.
 

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