Progressive vs traditional mount point merits

[Wes Mantooth]

-5 or -6 all day. But it of course depends on the ski. I’m all about more progressive skis these days I.e the playful chargers and I come from a race background. I don’t find you have to ski super centered I feel like with the right ski at -5 you can still drive hard from the front and then slash and dump speed on a dime. So much poppier and more fun in the air too

[Johnny Utah]

There is mount preference within the designed mount area and then there is the actual designed mount area. Both are subject to preference and could be described by words like “progressive” and “traditional.” No?

Coming back to this. How would folks describe the consequences of more extreme ranges:

1. A more progressive ski design with say a -5 recommended line, but mounted at…
(A) -10
(B) 0

2. A more traditional ski design with a -10 recommended line, but mounted at…
(C) -15
(D) -5

If you’re an average-sized human and a very capable skier, and all 4 of these skis were handed to you… which do you expect would be the most enjoyable (just ride em) or most FUBAR’d (remount before they touch snow again)?


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[Marshal Olson]

Interesting thread!

Firstly, more often than not, Midsole line is at the center of the sidecut (the narrowest point of the ski). However some skis move the recommended line forward of this. Lots of examples, but one I know is the Praxis GPO. The dimple was +1.5 from the center of the sidecut on the pair I had. Unsurprisingly, many recommendations in the GPO thread suggest going ~1.5 from the dimple when mounting those skis.

Additionally, something that has been mentioned, but not really unpacked, is that best results come from matching midsole line to biomechanics. What is missed is that the easiest way to figure that out is by your boot (since it is holding you in place)...

(1) What size
(2) What is the cuff angle

Generally speaking, midsole lines are defined by an idealized boot size (typically Mondo 27). I think Hoji has offered really good explanations on this already, so in summary for every 1cm different from that, most folks benefit from adjusting 5mm. 2cm smaller boot (ie a mondo 25) more often that not, will benefit from +1. Same logic applies to larger boots moving backwards slightly.

A more closed ankle forces your weight more forward (Aka driving the cuff) and a more open ankle moves your center of mass backwards, relatively speaking. As such, more upright cuff angles like more forward mounts (more neutral stance) and more lean angle like more rearward mounts (more athletic stance).

Example is that my Touring boots are ~14deg. I am skiing more consistent snow, in a more neutral stance (mainly because I want less muscle activation while skiing since firing those muscles extensively on the up). My Alpine boots, which have a 20deg cuff angle to close the ankle and activate large muscle groups only while descending (based on my own physiology femur/tibia ratios etc... this is NOT universal). As such, I typically mount my touring setups +1 to +1.5 from my alpine mounts to account for my stance (as defined by the boot).

In summary, consider thinking about mounts this way...

(1) where is the center of the sidecut of the ski.
(2) how big is your boot -> 27mondo / 310ish BSL as baseline and add/subtract from there.
(3) how much forward lean do you run? -> 15-17deg is baseline and add/subtract from there.

This makes the relative mount position to be an OUTPUT number, not the input number.



**NOTE ON FINDING THE CENTER OF THE SIDECUT**
(1) Measure the actual width of the ski near the midsole with quality micrometers.
(2) Round that up to the next whole number if a fraction and then add one or two mm to that (ie 96.5mm -> 98-99mm)
(3) Set your micrometer to that number as closely as possible and lock it with the thumbscrew.
(4) Starting from the midsole and moving toward the tip, slide the micrometers perpendicularly to the edge until you find this width (ie 98-99mm)
(5) Put a small mark on the edge with a sharpie
(6) Repeat on the tail, finding and marking the same width
(7) Measure this lenth, halve it, and then mark the center of the sidecut.

Where the center of the sidecut is, relative to the overall length of the ski is defined by how much tip taper vs. tail taper there is and how much edge taper (tail to tip width delta where 120-100-110 ski has 10mm of tail delta) there is. So a ski with equal tip and tail taper and no edge taper angle (same width tip/tail) has its center of sidecut at 0. A ski with 300mm tip taper and 200mm tail taper, and an 8mm tail taper delta is going to have a center of sidecut around 7.5-8mm from center of the chord length of the ski.

Of course, there are also style and personal preference factors too, but the above is intended to be a simple baseline/starting point.

[whambat]

I’m loving this discussion. For me my mounts are all over the place from ski to ski when looking at from center. But most are on or near the recommended line. I have a pretty big quiver with different types of skis, mostly I pick up hardly used for cheap. I have 187 Bonafides and 192 LP105s behind the line because I just moved the heel back from the original owner who probably had a 27 shell vs my 28 shell size so, I’m about 11-12cm from center. But, then I have 194 Black Crow Animas I have mounted at 1 cm forward for about 5cm from center. I also have 188 Invictus Ti mounted on the line for 8cm back from center. Then my frontside skis are 177 Stockli SR 85, I don’t know what the line is on those but I’m guessing 11cm back from center. When I had park skis, I had them mounted on whatever progressive mount line they had. Yet, I don’t feel like I really ski that much differently from ski to ski. I attribute that to the ski design. Those Animas would be a pretty traditional mount of 9-10 back from center if I lopped off the twin tip and tail rocker, and a pretty short ski. If I added a twin tip and tail rocker to the Bonafides, I’d end up with a pretty progressive mount. I tried a pair of 188 Animas and was going OTB in any powder, but it was also such a short tip it was as if I was skiing a 175 traditional mount ski: so no wonder. I consider my self a mostly center weighted skier, with maybe a little more forward at start of turn and maybe a little more back at end of turn, which has always been considered classic as g forces move you around.

I don’t think boot cuff angle matters as much to your COM as has been suggested. If you have a forward angle of 20, your knee is bent pretty good, moving your rear behind center. You get back over the center of your boots by having a more forward spine angle: a classic racer stance. On the other end if you had really upright boots, you have less knee bend, and a more upright upper body, but you should still end up pretty centered. Both positions can end up driving your shins, and be centered. Or you can be extremely backseat from both an upright stance or with a deep knee bend if you don’t appropriately match your angles; the classic PSIA description of match spine angle to shin angle.

I guess I’m saying, if a ski is progressive, mount it progressive, but have a long enough ski to have enough tip to prevent dive if you are going to ski powder. If it’s traditional, mount it traditional. If you feel off balance from that, get your center of mass over your feet.

[D(C)]

I thought I liked more forward mounts, but the skis that convinced me of that were Hoji designs, which have easy, loose tails. With a more traditional shape, particularly if the tail doesn’t have much taper or rocker, a forward mount can make the tails feel a bit punishing and the ski feel a bit unbalanced overall.

[Mustonen]

The last couple skis I’ve gotten I had to go back one or two cm to really gel with them: (Ranger 107, Corvus, feels like a couple others). I’m fine throwing skis sideways, but I find that on any kind of hard pack, even roughed up or a little cruddy, I want to lean into the tips and that just doesn’t seem to work with a progressive mount point. I don’t HAVE to lean into the tips, but I have more fun if I can.

I’m more tolerant of the progressive mount in deeper snow/chop, but also question the benefits a bit more if I’m not flippy/spinny/switchy, which I decidedly am not.

And to counterpoint, I preemptively mounted my sender squads on the rearward line, 2cm back from recommended. And that was the wrong call. They were fine there, but only fine. Remounting them to recommended and goddamn do they feel better, I just have to stop thinking about all that tail behind me….

[Mustonen]

Interesting thread!

Generally speaking, midsole lines are defined by an idealized boot size (typically Mondo 27). I think Hoji has offered really good explanations on this already, so in summary for every 1cm different from that, most folks benefit from adjusting 5mm. 2cm smaller boot (ie a mondo 25) more often that not, will benefit from +1. Same logic applies to larger boots moving backwards slightly.

I’ve spent some time thinking on this and always intuited the opposite. The bigger the boot/foot the further back my leg/lever is moved back on the ski. Controlling for other variables (height, femur length, etc.) I’d suggest that the bigger the boot, the more inclined you would be to move forward, not backward. Happy to be wrong and understand why though.

[XXX-er]

ok but isnt boot center still boot center ?

[lowsparkco]

ok but isnt boot center still boot center ?

For sure. But, I think Marshall’s point is that isn’t exactly where your Center of Gravity ends up. All things being equal in a bigger boot your toes are creeping further and further up the ski. So is the cuff. Cheating it back a smidge can keep you in the center of the side cut.

[Shorty_J]

ok but isnt boot center still boot center ?

This is what people are talking about when they say "ball of foot at cord center".

The recommended mount point (relative to boot center) is usually behind the narrowest part of the ski (cord center-ish).

My short foot probably has the ball of my foot about 8cm forward of the center of the boot but someone in a 27 boot is probably 9cm from the center of the boot to the ball of their feet.

So if I move 1cm forward in my size 25 I'm putting my ball of foot at the same point as the guy with the average 27 boot.

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[J. Barron DeJong]

Generally speaking, midsole lines are defined by an idealized boot size (typically Mondo 27). I think Hoji has offered really good explanations on this already, so in summary for every 1cm different from that, most folks benefit from adjusting 5mm. 2cm smaller boot (ie a mondo 25) more often that not, will benefit from +1. Same logic applies to larger boots moving backwards slightly.

If you move the boot centerline following this rule, it’s the same as saying the the position of the binding toe piece stays constant regardless off boot size, and only the heel piece is moved.

Does that seem right? I haven’t played with mount points on my skis, and I’m stuck with my own feet, so can’t play with boot size, but it seems to me that the toe piece should be moving somewhat as boot sole length grows or shrinks, even if the heel should maybe be moving more?

[Marshal Olson]

If you move the boot centerline following this rule, it’s the same as saying the the position of the binding toe piece stays constant regardless off boot size, and only the heel piece is moved.

Does that seem right? I haven’t played with mount points on my skis, and I’m stuck with my own feet, so can’t play with boot size, but it seems to me that the toe piece should be moving somewhat as boot sole length grows or shrinks, even if the heel should maybe be moving more?

Close, but it is halving the different from midsole, not the full amount (ie +1 if boot is 2cm smaller). The intent, as Shorty_J explained is to approximate keeping the ball of foot in a similar position.

[Marshal Olson]

For sure. But, I think Marshall’s point is that isn’t exactly where your Center of Gravity ends up. All things being equal in a bigger boot your toes are creeping further and further up the ski. So is the cuff. Cheating it back a smidge can keep you in the center of the side cut.

Ya, exactly. If you stand straight up (locked knees, etc), all your weight is on your heels, and you can lift your toes from the ground. as you crouch down into a more athletic/powerful position, your weight goes to the ball of foot/toes, and your heel eventually lifts from the ground.

[J. Barron DeJong]

Close, but it is halving the different from midsole, not the full amount (ie +1 if boot is 2cm smaller). The intent, as Shorty_J explained is to approximate keeping the ball of foot in a similar position.

Correct me if I’m misinterpreting what you’re saying here - maybe I’m just a bit dense today - but if my boot grows 20mm and I keep the toe piece in the same location, then my heel would move back 20mm, and my boot center would have moved back 10mm, right?

So if you’re saying move the boot center back 10mm for every 20mm increase in length, that’s the same as my example above, and the toe piece hasn’t moved?

I’m not disagreeing with the principle, it just seems like if the goal is to keep the the ball of the foot in the same location, then moving boot center back something like 6 or 8 mm for each 20mm increase in length would be a closer guideline?

[kc_7777]

Interesting thread!

Additionally, something that has been mentioned, but not really unpacked, is that best results come from matching midsole line to biomechanics. What is missed is that the easiest way to figure that out is by your boot (since it is holding you in place)...

(1) What size
(2) What is the cuff angle

Generally speaking, midsole lines are defined by an idealized boot size (typically Mondo 27). I think Hoji has offered really good explanations on this already, so in summary for every 1cm different from that, most folks benefit from adjusting 5mm. 2cm smaller boot (ie a mondo 25) more often that not, will benefit from +1. Same logic applies to larger boots moving backwards slightly.

A more closed ankle forces your weight more forward (Aka driving the cuff) and a more open ankle moves your center of mass backwards, relatively speaking. As such, more upright cuff angles like more forward mounts (more neutral stance) and more lean angle like more rearward mounts (more athletic stance).

Example is that my Touring boots are ~14deg. I am skiing more consistent snow, in a more neutral stance (mainly because I want less muscle activation while skiing since firing those muscles extensively on the up). My Alpine boots, which have a 20deg cuff angle to close the ankle and activate large muscle groups only while descending (based on my own physiology femur/tibia ratios etc... this is NOT universal). As such, I typically mount my touring setups +1 to +1.5 from my alpine mounts to account for my stance (as defined by the boot).

In summary, consider thinking about mounts this way...

(1) where is the center of the sidecut of the ski.
(2) how big is your boot -> 27mondo / 310ish BSL as baseline and add/subtract from there.
(3) how much forward lean do you run? -> 15-17deg is baseline and add/subtract from there.

This makes the relative mount position to be an OUTPUT number, not the input number.

**NOTE ON FINDING THE CENTER OF THE SIDECUT**
(1) Measure the actual width of the ski near the midsole with quality micrometers.
(2) Round that up to the next whole number if a fraction and then add one or two mm to that (ie 96.5mm -> 98-99mm)
(3) Set your micrometer to that number as closely as possible and lock it with the thumbscrew.
(4) Starting from the midsole and moving toward the tip, slide the micrometers perpendicularly to the edge until you find this width (ie 98-99mm)
(5) Put a small mark on the edge with a sharpie
(6) Repeat on the tail, finding and marking the same width
(7) Measure this lenth, halve it, and then mark the center of the sidecut.

Where the center of the sidecut is, relative to the overall length of the ski is defined by how much tip taper vs. tail taper there is and how much edge taper (tail to tip width delta where 120-100-110 ski has 10mm of tail delta) there is. So a ski with equal tip and tail taper and no edge taper angle (same width tip/tail) has its center of sidecut at 0. A ski with 300mm tip taper and 200mm tail taper, and an 8mm tail taper delta is going to have a center of sidecut around 7.5-8mm from center of the chord length of the ski. Of course, there are also style and personal preference factors too, but the above is intended to be a simple baseline/starting point.

This was really really good. I have Head Kore 1 boots, which have forward lean of 14°, and I now cram my different sized feet to fit the smaller foot into 24 mondo shells. So based on 2 of the output factors, it makes sense that I like more forward mounts, eg +1cm to +2cm, and around -4cm to -6cm. I also ski centered. Thanks Marshal!

My current quiver mounts are pretty consistent, between -4cm and -6cm, only slight outliers are the E88 (-7cm) and Season Aero (-3cm).

Looking at getting a 185cm Season Pass for pow touring, and rec is -4cm on those.

And I've finally stopped looking at traditional shaped skis, with flat tails with no taper or rockerand recs at -10cm and -11cm, ...I’ve tried them and can ski 'em, but know I won't get along with them.

KC

[J. Barron DeJong]

Correct me if I’m misinterpreting what you’re saying here - maybe I’m just a bit dense today - but if my boot grows 20mm and I keep the toe piece in the same location, then my heel would move back 20mm, and my boot center would have moved back 10mm, right?

So if you’re saying move the boot center back 10mm for every 20mm increase in length, that’s the same as my example above, and the toe piece hasn’t moved?

I’m not disagreeing with the principle, it just seems like if the goal is to keep the the ball of the foot in the same location, then moving boot center back something like 6 or 8 mm for each 20mm increase in length would be a closer guideline?

Coming back to this - since I have a habit of beating a dead horse (and because I’m avoiding doing actual work):

If you were to shift the boot midsole back only 2mm from the recommended mount point for each 1cm increase in boot size (or forward 2mm for each 1cm decrease), that keeps the 70% of foot length location at the same position on the ski as you move through the size range. (70% seems like a reasonable approximation of ball-of-foot.)

[SoVT Joey]

Coming back to this - since I have a habit of beating a dead horse (and because I’m avoiding doing actual work):

If you were to shift the boot midsole back only 2mm from the recommended mount point for each 1cm increase in boot size (or forward 2mm for each 1cm decrease), that keeps the 70% of foot length location at the same position on the ski as you move through the size range. (70% seems like a reasonable approximation of ball-of-foot.)

No but yes, that’s seems convoluted and difficult. Somewhere on 4frnt’s site was a breakdown of how hoji mounts. I can’t find it.

it’s probably a lot easier to draw it on paper to understand it.

http://mtnguiding.com/media/2017/1/4...adesravens-too

[Mustonen]

I love the overanalysis (truly). All of us have, for years, mounted around the recommended point for skis. So big boots and small boots and long femurs and short torsos and 6 toes and everything else, we’ve adjusted to accommodate our place within the world. I really like to stand on my toes. Bushwacka loves to tailgun it and double pole plant. What feels weird to me vs what feels weird to him will probably be pretty similar, because we do what we do and are used to similar gear.

This data is fun, but it’s really easy to overstate its usefulness. Everything is too wonderfully complex to ever be captured within any single metric or analysis or TGR thread.

[J. Barron DeJong]

No but yes, that’s seems convoluted and difficult. Somewhere on 4frnt’s site was a breakdown of how hoji mounts. I can’t find it.

it’s probably a lot easier to draw it on paper to understand it.

http://mtnguiding.com/media/2017/1/4...adesravens-too

Yeah, I found that Hoji recommendation, and it’s the same as Marshall was saying, which ends up as “keep the toe piece in the same location regardless of BSL”.

And after going through the analysis, adjusting for BSL is probably a few rungs down the ladder in factors affecting choice of mount point.

Now that I’ve done it though, you better believe I’m mounting my R87s 2mm behind the recommended line to accommodate my 28.5 boots

[XXX-er]

For sure. But, I think Marshall’s point is that isn’t exactly where your Center of Gravity ends up. All things being equal in a bigger boot your toes are creeping further and further up the ski. So is the cuff. Cheating it back a smidge can keep you in the center of the side cut.

^^does it still apply to me in a 24, what happens to an AZN in a small boot ?

obviuosly getting into a binding setup for a bigger boot would put my BSL forward of BC

[kc_7777]

Not helping here but today I skied my 184cm Ravens, with new boots that are approx 1cm shorter in the sole….so that puts me 0.5cm further forward compared to last year. I was at -5.5, so am now at -5cm.

I swear they were not as dialed as last year…Fack.


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[yeahman]

Not helping here but today I skied my 184cm Ravens, with new boots that are approx 1cm shorter in the sole….so that puts me 0.5cm further forward compared to last year. I was at -5.5, so am now at -5cm.

I swear they were not as dialed as last year…Fack.


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Nah. You're one year older and your skills have declined 0.5%.

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[lowsparkco]

^^does it still apply to me in a 24, what happens to an AZN in a small boot ?

obviuosly getting into a binding setup for a bigger boot would put my BSL forward of BC

Yes, I think it happens to you too, in a 24 mondo.

So, if “the line” is for a 27 shell with say a 318 mm BSL and you’re mounting a 24 shell with 280 mm BSL then your probably around +2 to get it to feel the same.

It’s not perfect because of the toe piece on the boots, but if you think I have 159 mm of foot in front of the line and you have 140 mm. My ball of my foot would be near the end of your boot, so you go plus 19 mm and we’re closer.

[Huskier]

This data is fun, but it’s really easy to overstate its usefulness. Everything is too wonderfully complex to ever be captured within any single metric or analysis or TGR thread.

Counterpoint, these types of deep dives can shed light on fit/style factors that, when accounted for, can help avoid what would have otherwise involved lot of trial and error frustration to figure out.

Ex: I spent the past year figuring out a funky chicken-inducing problem ski, worse in my touring boot. Turns out it was a combination of boot too upright, but also mount in the wrong place on the sidecut . Pushed my mount forward, increased my ramp delta and poof, prob solved. I went and measured using the method Marshal describes above: Surprise surprise it's the same spot. Ski sorcery.

[kootenayskier]

I love the overanalysis (truly). All of us have, for years, mounted around the recommended point for skis. So big boots and small boots and long femurs and short torsos and 6 toes and everything else, we’ve adjusted to accommodate our place within the world. I really like to stand on my toes. Bushwacka loves to tailgun it and double pole plant. What feels weird to me vs what feels weird to him will probably be pretty similar, because we do what we do and are used to similar gear.

This data is fun, but it’s really easy to overstate its usefulness. Everything is too wonderfully complex to ever be captured within any single metric or analysis or TGR thread.

Absolutely. At this point in my life it’s all about finding the gear that is adapted to me and my (deeply ingrained) quirks, rather than vice versa. I developed my fundamentals as an instructor and coach on 210 GS skis in the late 80s, so I’m as traditional as it gets in my preferences: Full Tilt Classics, STH2s, and rear mounted DPSs and Volkls. On the occasions I’ve spent time screwing around with mount points (using demo tracks) I almost always prefer them on the line (with my 318 bsl), but occasionally +1.