Binding ramp angle differences

[jonc]

These are somewhat arbitrary, but some of the definitions above do not correspond to the terminology as I've generally seen it used. Here are, I believe, some more precise definitions:

DELTA: Heel height - toe height, measured at the contact points with the boot (heel at most rearward end of contact area, toe at most forward end of contact area); generally given in mm. The advantage of using delta is it allows a single specification for each binding, since this doesn't vary with BSL (that's why the mfrs. use delta instead of ramp angle). It's called delta because the greek letter ∆ (delta) is used in science and engineering to specify a difference. E.g, ∆E means the difference energy between two states.

Elite racers will sometimes adjust their deltas depending on the event, but most good recreational skiers will want to find a single delta at which their fore-aft balance is optimized in all conditions (this is boot-specific, but is essentially independent of what ski you are using). @bud heishman can confirm this, but most good recreational skiers need to have their delta right to within 1 mm to have their fore-aft balance dialed in. Once you've found it, ideally you want to use it on all your skis. But what happens when you buy new boots? Well suppose your optimum delta was 4 mm in the old boots, and your bindings were all likewise conveniently 4 mm. But then you buy new boots in which you need a delta of 2 mm to be balanced. In that case, you don't want to shim all your skis; instead you just gas-pedal the new boots by 2 mm.

[I'm very sensitive to fore-aft balance because mine's currently messed up -- my alignment specialist and I have concluded I can't achieve it it my current boots, so I have to get new ones!]

RAMP ANGLE: The angle of the boot's outer sole that results from the delta (i.e., I've generally seen it used to refer to the external angle, not the internal bootboard angle, which is referred to as "zeppa"). Ramp angle = arcsin(d/x), where d is the delta and x is the distance between where the heelpiece and toepiece contact the bottom of the boot (and is thus less than the BSL, though as an approximation you could use the BSL). As a general rule, you get 1 degree of ramp angle for every 5 mm of delta (so the pic above showing four degrees of ramp angle would actually require 20 mm of delta!). WC skiers can sense changes in their delta of 0.5 mm, which is only 0.1 degrees! Recreational skiers that are sensitive to their fore-aft balance can sense 1 mm, which is only 0.2 degrees.

HOWEVER: The phrase "ramp angle" really can refer to the angle of anything made with a pitch, so there's nothing technically wrong with using "ramp angle" to refer to bootboard angle. You just have to be clear in how you define your terms.

ZEPPA: The internal angle of the bootboard. Because that's the key specification for a bootboard, some actually refer to the bootboard itself as "the zeppa.

I wanted to pull this into its own thread separate from the gear review because I thought it was great info. And I have some questions.

How important is delta/ramp angle to one's skiing? You mentioned a recreational skier may be able to sense a variation as small as 1mm.

To get more specific on my own gear I have 2 skis: Blizzard Bushwacker with Look PX12 bindings (internet searches show that it has a delta of 4mm, I also did a rough measurement which confirms this) and Head Titan with PRX12 bindings (according to previous information on this site has a delta of 9.5mm, again rough measurement to confirm). It sounds like maybe I would have been better with the PDX12 with a similar ramp angle? Clearly there is a delta of 4+mm. Now these 2 skis definitely do not ski the same however I was chalking that up to differences in the ski itself. What specifics might/should I notice based on the ramp angle differences?

Is it worth exploring adjusting the delta? What changes might I be able to make? Can I even do that without going to the shop for parts?

 

[AmyPJ]

You could put a toe lifter on the PRX bindings I'd guess. I did that with some bindings I had on a pair of Sambas I skied last winter. I finally realized the angle on them was quite a lot steeper than any of my other skis. That, coupled with a short BSL, made for a pretty big difference that I absolutely could feel, but didn't recognize until I really started paying attention to such things.

Now, I look for bindings that are fairly level.

 

[cantunamunch]

What specifics might/should I notice based on the ramp angle differences?

Is it worth exploring adjusting the delta? What changes might I be able to make?

These questions are best answered by a high level instructor who has skied with you.

You can experiment with delta on the cheap - all it takes is some basic shims and longer screws - BUT you will not get any definite answers by making a limited number of changes and observing 'feel' differences.

For two reasons (1) your geometry in your boots is not a known, well controlled quantity and (2) your body will adapt to the new delta and the new feel within hours, days at the most, unless the new ski setup is SO bad that you're effectively handicapping yourself.

 

[Philpug]

This is a topic that we have been bouncing around for a while and just trying to figure out how to present it. @cantunamunch offered to help with setting up a program that will help us determine what ramp angle would be for each skier in each binding. Since I started the discussion with him, we have been gathering binding information from toe & heel height. Ramp is important for sure.

 

[Philpug]

I wanted to pull this into its own thread separate from the gear review because I thought it was great info. And I have some questions.

How important is delta/ramp angle to one's skiing? You mentioned a recreational skier may be able to sense a variation as small as 1mm.

To get more specific on my own gear I have 2 skis: Blizzard Bushwacker with Look PX12 bindings (internet searches show that it has a delta of 4mm, I also did a rough measurement which confirms this) and Head Titan with PRX12 bindings (according to previous information on this site has a delta of 9.5mm, again rough measurement to confirm). It sounds like maybe I would have been better with the PDX12 with a similar ramp angle? Clearly there is a delta of 4+mm. Now these 2 skis definitely do not ski the same however I was chalking that up to differences in the ski itself. What specifics might/should I notice based on the ramp angle differences?

Is it worth exploring adjusting the delta? What changes might I be able to make? Can I even do that without going to the shop for parts?

Unfortunately most system bindings do not allow for adjusting the ramp and this binding is one of them.

 

[WheatKing]

Curious about this as well. Look forward to the topic once you guys get it sorted. I have my own ideas of why it might be important.. and thinking about it, might be partially due to why I also like my bindings mounted a bit forward of center.

 

[Erik Timmerman]

I would expect that on the Heads you would feel like you can't get forward, like the ski is all tail. If that's a system binding, it could be really hard or even impossible to change the delta. If you loved that setup, you could lift the toes of your boots, and then lift the heels on your Looks so that both skis feel right.

As for a short term experiment, you can try jamming toe shims in between your boot and the binding, probably not recommended, but you could do it, just saying and will neither confirm nor deny that I have ever done this myself or with a student. The best way to experiment is with a plated race ski, a box of screw, some shims and a posidriver. I now know just where I want my skis to be, and I also know the feelings of not being there, which makes it pretty easy to rule things out and adjust.

 

[jonc]

I would expect that on the Heads you would feel like you can't get forward, like the ski is all tail. If that's a system binding, it could be really hard or even impossible to change the delta. If you loved that setup, you could lift the toes of your boots, and then lift the heels on your Looks so that both skis feel right.

As for a short term experiment, you can try jamming toe shims in between your boot and the binding, probably not recommended, but you could do it, just saying and will neither confirm nor deny that I have ever done this myself or with a student. The best way to experiment is with a plated race ski, a box of screw, some shims and a posidriver. I now know just where I want my skis to be, and I also know the feelings of not being there, which makes it pretty easy to rule things out and adjust.

It sounds like per Phil's response above that this PRX binding is not adjustable. The PRD binding option is adjustable and has a lower delta to start with. That has me curious why the manufacturer would use such a high delta on their binding if it would tend to make the skier fall back on the tails a bit more. Would moving the bindings forward a bit make up for this?

 

[jonc]

For two reasons (1) your geometry in your boots is not a known, well controlled quantity and (2) your body will adapt to the new delta and the new feel within hours, days at the most, unless the new ski setup is SO bad that you're effectively handicapping yourself.

Why isn't the boot geometry a controlled quantity? I use the same boots on both skis, do you mean slop within the boot? Or heel lift or other adjustments?

If I will naturally adapt to it then does it make a difference? Or will I just adapt to the new feeling and not notice its impact on my skiing.

 

[Erik Timmerman]

Why isn't the boot geometry a controlled quantity? I use the same boots on both skis, do you mean slop within the boot? Or heel lift or other adjustments?

He means relative to other boots. It's hard for a binding manufacturer to settle on one delta when all the boots have different geometries. Who is to say what is right?

 

[jonc]

He means relative to other boots. It's hard for a binding manufacturer to settle on one delta when all the boots have different geometries. Who is to say what is right?

That makes sense so does that mean they're targeting the bindings to a general category of boots? Say beginner boots with high delta binding, intermediate with less delta, advanced/racer with no delta?

 

[cantunamunch]

That makes sense so does that mean they're targeting the bindings to a general category of boots? Say beginner boots with high delta binding, intermediate with less delta, advanced/racer with no delta?

The recreational markets are not even remotely that tidy; racer bindings are all available with shim kits.

 

[Erik Timmerman]

That makes sense so does that mean they're targeting the bindings to a general category of boots? Say beginner boots with high delta binding, intermediate with less delta, advanced/racer with no delta?

I think it's more likely that a brand will be trying to make all of it's "stuff" work together. For example, I have not felt any need to adjust the delta on any of my Nordica skis when using Nordica boots. Good thing, since on some of them it can't be changed.

 

[sinbad7]

This is one of my pet topics, so I'll be watching closely.

After years of demoing skis I've always felt better fore-aft balance on a binding with a decent amount of delta, say 5mm. I have little in the way of dorsiflexion, and stick a heel wedge inside all my boots, so that extra 'tip forward' seems to help.

I've taken basic measurements for each of my own skis to keep a rudimentary log of the toe/heel heights for each setup. Bindings seem to have been flattening out over the time I've been paying attention - around the last ten years. Must say I've not ever run across a delta of 9.5mm though. That's large.

In all my demos I've only ever felt much too far forward on one ski - a short Elan Speedwave 14 owned by a friend - and he's had that one shimmed to suit himself. I keep forgetting to measure the delta on those.

There are so many variables at play it's going to be nigh on impossible to come up with a rule of thumb here. Just about everything plays a part in determining someone's fore-aft balance.

 

[jonc]

I think it's more likely that a brand will be trying to make all of it's "stuff" work together. For example, I have not felt any need to adjust the delta on any of my Nordica skis when using Nordica boots. Good thing, since on some of them it can't be changed.

Wouldn't that only work for companies that actually make both boots and bindings? From what I've seen there are a lot more boot makers than binding makers.

 

[Muleski]

I think it's more likely that a brand will be trying to make all of it's "stuff" work together. For example, I have not felt any need to adjust the delta on any of my Nordica skis when using Nordica boots. Good thing, since on some of them it can't be changed.

I think that's a good point. It seems like this "topic" has been discussed all over the place in recent years, by a "wide horizon" of skiers.
This is not new in the high end race world. Our son was part of a three person test team, on snow for over 20 days, to sort some of this out for a WC winner about 5-6 years ago.

If we look at any of the ski companies, most spend a fair amount of time on design and R&D. Head sure does. So, I take some of the recommendations that the off the shelf binding delta is "wrong" and that everybody should modify it the same way {regardless of many other factors, like boots and the skier's physiology.} with a grain of salt. There are many factors.

However, it just seems logical that the stock setup has been pretty well thought out, and might be effective for most. I could very well be all wrong.

I have a couple of pairs of Head i.speed cheaters. Have a pair of Dynastar cheaters. Two pairs of Head WC SL's. Then I have five other pairs of skis that are all set up with STH2 16's. Have no desire to modify the delta on any of them. They are all fairly close. I have a pair of Firearrow 84 EDT's. I can't do a thing with them anyways, but they seem fine.

Now I know, from my son's testing over years, and work in the biz, that the ramp angle on most "real" WC boots is pretty similar. About 2.5 degrees. The boots are more alike than dissimilar. Once you move out of that realm, they differ.

When I recently moved out of a plug, after many years, I noticed a more upright stance, which I came to prefer in all of my soft snow skis, and pretty quickly adapted to on the hard snow skis. Never thought of changing the delta on the skis.

I think it might be that this buffet of stuff does all work together, for me, for how and where I ski.

My son spends a huge amount of time and energy to get this individually right for his athletes. He also tweaks it. These are high level kids. Are they all set up the same way? Nope. They are set up the right way for them.
A lot of work, but not everybody is zero'd out, at all.

Our daughter is a former NorAm NCAA racer. She could not wait to get in her first ever non plug boots. She skis almost every day of the winter, and has a real wide range of skis. When she was racing, this was important stuff. Now, if I were to ask her about the delta on her various skis, she would laugh, say she has no clue, and "who cares." She lives in a great mountain town, and she can really ski. On anything. When she was at the top of the race game, skiing on injected "snow", making the same relative turn shapes, she, her tech and coaches had this dialed in. And she could sense very minor differences. And knew what timed fast.

Now, it doesn't seem to be a big concern. I think she has five different bindings on her skis, as well.

But it clearly is a big concern for many, who feel that it is a big component to maximizing their skiing and fun! And I hear a lot of you say that it does. And I realize that this is not the top of the race game.

The point that there are more skis where you can NOT alter delta than ones where you can is worth noting for some considering this. Yes, every real adult race binding can be shimmed. At one point I bet we had 200+ shims in our house, and a few thousand screws!

I also have NEVER seen a pair of demo skis, with demo bindings where you could alter the delta. So does that impact impressions? Never has for me. Then again I don't demo much. Like never. I borrow skis, or kids hand them to us. So I am out of touch there.

It's interesting stuff to me. I am ALL FOR skiers being aware of what works best for them, and trying to do what is best for them. All good! Worth repeating.

Skied last winter with two old friends, both in their 60's, both ex USST. Somehow this topic came up and we all laughed. One guy said that he had enough other stuff to deal with. No clue of their binding delta. Not on their radar. Their skis worked. "Yeah, I like these....I can still lay them over!" And he could.

Ask any good U14, and they know, and think they know how all of their WC heros are set up. As well as how they are set up, or think they are! I have a friend who has all of his boys convinced that they are set up like Hirscher for SL, and Ligety for GS, just to take it off the table and out of their heads!

No offense gang, I would love to be able to feel a 1mm or 2mm difference. Maybe I need to pay more attention to this. I say that seriously. I am all over the place. My brother's theory is that if you've been at this "a while",you just adapt. He always looks really well balanced, fore and aft, on his skis. If anything, he likes more delta. It's what he's comfortable with. Muscle memory, force of habit? Dunno? No way are his binding delta's the same, just thinking through the skis.

I really feel like a dinosaur at times, and this is one. Keep posting and I'll keep reading with interest.

 

[Erik Timmerman]

Wouldn't that only work for companies that actually make both boots and bindings? From what I've seen there are a lot more boot makers than binding makers.

...and there-in lies the problem, though most of the boot manufacturers are tied up or partnered with a binding in some way.

 

[ScotsSkier]

I think that's a good point. It seems like this "topic" has been discussed all over the place in recent years, by a "wide horizon" of skiers.
This is not new in the high end race world. Our son was part of a three person test team, on snow for over 20 days, to sort some of this out for a WC winner about 5-6 years ago.

If we look at any of the ski companies, most spend a fair amount of time on design and R&D. Head sure does. So, I take some of the recommendations that the off the shelf binding delta is "wrong" and that everybody should modify it the same way {regardless of many other factors, like boots and the skier's physiology.} with a grain of salt. There are many factors.

However, it just seems logical that the stock setup has been pretty well thought out, and might be effective for most. I could very well be all wrong.

I have a couple of pairs of Head i.speed cheaters. Have a pair of Dynastar cheaters. Two pairs of Head WC SL's. Then I have five other pairs of skis that are all set up with STH2 16's. Have no desire to modify the delta on any of them. They are all fairly close. I have a pair of Firearrow 84 EDT's. I can't do a thing with them anyways, but they seem fine.

Now I know, from my son's testing over years, and work in the biz, that the ramp angle on most "real" WC boots is pretty similar. About 2.5 degrees. The boots are more alike than dissimilar. Once you move out of that realm, they differ.

When I recently moved out of a plug, after many years, I noticed a more upright stance, which I came to prefer in all of my soft snow skis, and pretty quickly adapted to on the hard snow skis. Never thought of changing the delta on the skis.

I think it might be that this buffet of stuff does all work together, for me, for how and where I ski.

My son spends a huge amount of time and energy to get this individually right for his athletes. He also tweaks it. These are high level kids. Are they all set up the same way? Nope. They are set up the right way for them.
A lot of work, but not everybody is zero'd out, at all.

Our daughter is a former NorAm NCAA racer. She could not wait to get in her first ever non plug boots. She skis almost every day of the winter, and has a real wide range of skis. When she was racing, this was important stuff. Now, if I were to ask her about the delta on her various skis, she would laugh, say she has no clue, and "who cares." She lives in a great mountain town, and she can really ski. On anything. When she was at the top of the race game, skiing on injected "snow", making the same relative turn shapes, she, her tech and coaches had this dialed in. And she could sense very minor differences. And knew what timed fast.

Now, it doesn't seem to be a big concern. I think she has five different bindings on her skis, as well.

But it clearly is a big concern for many, who feel that it is a big component to maximizing their skiing and fun! And I hear a lot of you say that it does. And I realize that this is not the top of the race game.

The point that there are more skis where you can NOT alter delta than ones where you can is worth noting for some considering this. Yes, every real adult race binding can be shimmed. At one point I bet we had 200+ shims in our house, and a few thousand screws!

I also have NEVER seen a pair of demo skis, with demo bindings where you could alter the delta. So does that impact impressions? Never has for me. Then again I don't demo much. Like never. I borrow skis, or kids hand them to us. So I am out of touch there.

It's interesting stuff to me. I am ALL FOR skiers being aware of what works best for them, and trying to do what is best for them. All good! Worth repeating.

Skied last winter with two old friends, both in their 60's, both ex USST. Somehow this topic came up and we all laughed. One guy said that he had enough other stuff to deal with. No clue of their binding delta. Not on their radar. Their skis worked. "Yeah, I like these....I can still lay them over!" And he could.

Ask any good U14, and they know, and think they know how all of their WC heros are set up. As well as how they are set up, or think they are! I have a friend who has all of his boys convinced that they are set up like Hirscher for SL, and Ligety for GS, just to take it off the table and out of their heads!

No offense gang, I would love to be able to claim that I feel a 1mm or 2mm difference. Maybe I need to pay more attention to thi. I say that seriously. I am all over the place. My brother's theory is that if you've been at this "a while",you just adapt. He always looks really well balanced, fore and aft, on his skis. If anything, he likes more delta. It's what he's comfortable with. Muscle memory, force of habit? Dunno? No way are his binding delta's the same, just thinking through the skis.

I really feel like a dinosaur at times, and this is one. Keep posting and I'll keep reading with interest.

I'm with you 110% here MS. To me a lot of this smacks of "snake oil" to be used in place of addressing more basic issues (remember, first rule of Masters racers - how can I buy an advantage) . As a modestly successful masters racer I regularly ski, and race, on a variety of different bindings - Marker Comp/piston plate, Tyrolia RD, Atomic Race, Atomic X series, Salomon STH and Look PX. I have a basic rule of thumb. Where I have shims available i use 2mm "gas pedal" on slalom and 1 mm on GS. Regardless of what the binding is... . Seems to work without too much additional thought - oh and I ski 2 or 3 different boots ... so i guess I am doing everything wrong.

And given that I am doing 100+ days a year on snow (135 last season) any minor changes should be pretty obvious?? ... Maybe I am just not skilled enough as an athlete/ professional coach but i suspect that most of us with decent experience simply adapt muscle memory to make the moist of what we happen to be on...... in the same way I ski different brands for all 4 events .And In the same way as a professional race driver will quickly adapt to what ever car is being provided - just do it!

Flak jacket on!

 

[bud heishman]

This topic is part of the whole boot "balancing" subject. The Sagittal plane is affected by four parameters which need to be coordinated effectively to optimize fore/aft balance. These four parameters are "ramp, forward lean, delta angle, binding mount position". This directly corresponds with PSIA's first skiing fundamental, "managing the relationship between the CoM (center of mass) and the BoS (base of support) along the length of the skis". Understand that small increments (ie: millimeters) under the feet have noticeable effects on the CoM which is relatively farther away from the angles created.

The "Delta" angle should not be confused with "stand height differential", the first is an angle created by boot sole length and stand height differential with longer boot sole lengths creating a lesser delta angle and a shorter BSL, creating a steeper delta angle. Ramp angle should not be confused with Delta angle as Ramp is generally understood as the internal angle created by the boot board/zeppa relative to the boot sole. These two parameters have totally different uses and affects in the coordinated effort of finding optimum balance.

If you would like to experiment easily and safely with delta angle and feel the effects of as little as 3mm difference (the minimum lifter plate thickness available for boot soles) you can cut up AFD sized pieces of "bontex" shims (pressed cardboard insole shims), available from your local boot fitter and use them to shim your bindings either between the AFD and boot sole or between the heel piece and boot sole. Or you can use a beer coaster from the bar! This approximately 1/8" shim will have a noticeable affect in fore/aft balance. While delta angle does not change the angle created inside the boot by the (ramp angle + forward lean angle), which should be assessed and adjusted first before assessing delta needs, it does change the lower leg angle. Changing the lower leg angle can be done with forward lean of the boot cuff however this is a mistake. Once the "net" forward lean angle (ramp + forward lean) is set for dorsiflexion needs these two angles should not be changed and the only way after this to change the lower leg angle is to change the delta angle.

Changing the delta angle changes our stance and affects the ability to pressure the shovels effectively at the top of the turns, affects our abilities to extend, affects our ability to balance on the little toe edge and ski one footed, affects our abilities to link a series of short turns remaining in balance. If the lower leg angle is too steep putting the knees too far forward over the BoS, the skier will be ineffective at moving pressure to the ski shovels above the fall line, find it impossible to extend fully or open the angle between the femurs and torso, find the hips must be kept aft of heels to remain in balance. Consequently, if the lower leg angle is too vertical the skier will find the boots feel stiffer as they lose the leverage advantage to flex it, find that they must now flex more at the waist to find balance (the only other place in the body we can flex forward besides the ankle).

When we get the delta right we will see the skier's generally taller stance has the lower leg angle matching the spine angle (parallel angles), flexion/extension occurs primarily through knee and hip joints and the skier is able to extend fully toward turn apex, fore/aft balance feels optimized and natural.

 

[bud heishman]

Muleski, I think all ski coaches should participate in some ski testing where they have an opportunity to change only one parameter at a time and feel the affects on their skiing performance. I have put together a quiver of identical skis, set up with three different parameters (delta, cant, mount position). Three pair for each parameter where the delta rotation included a neutral or stock ski, a ski with 10mm of increased toe lift and a ski with 10mm of increased heel lift.

When the testers skied on these different set ups they became keenly aware of how their bodies automatically adapted to the changes and how their fellow testers looked while skiing the different parameters. This is a huge benefit to coaches and instructors to learn to identify and separate technique issues from equipment issues and know when to consider alignment work.

I told Phil if we ever have a gathering in Tahoe area I would be happy to put something together like this again for members to test.