Base and edge bevel controls predictability of ski

[Wilhelmson]

Found this on the internet, credited to Epic but without an author. I'll just drop it here.
Edit: Credit @Bob Barnes
Moved to its own thread.



Base Edge Bevel--primarily controls "predictability" and how far a ski must be tipped before the edge engages

• Optimal bevel: Flat (unedged) ski is predictable, not "grabby"; skis are easily steered through the transition; edges engage smoothly but positively when appropriately tipped, and can still be "feathered" into a skid when needed.
• More bevel: Ski must be tipped further before the edge engages, allowing you to incline further into the turn before it hooks up and starts carving. Some strong skiers prefer this, especially those who prefer to stand fully on their skis with minimal "unweighting" through the transition, as they roll the skis from edge to edge. (This is rare, but I know a very strong racer who, for a while, tuned his slalom skis with a 3 degree base edge bevel, requiring him to move way inside the turn before the skis, which were then on a huge edge angle, started carving a very tight radius turn. The downside is later edge engagement; upside is incredibly tight carving radius when the edges finally do engage.)
• Too much bevel: flat skis are "swimmy" and do not feel like they'll hold very well, because you have to tip them a long way to get them to grip.
• Less bevel: Ski edge engages quickly when minimally tipped: ski is less forgiving, and requires very accurate, precise, and consistent movements.
• Too little bevel: Ski is "grabby" and unforgiving, difficult to steer smoothly, and very uncomfortable when flat on the snow, and "catching an edge" is more likely when skidding or sideslipping.
• Too little bevel: ski wants to hook up too quickly, trying to carve before you are sufficiently inside the turn for balance; the sensation is that the ski keeps coming back underneath you as you try to roll it onto edge to carve. Strong skiers with sophisticated pressure management skills may prefer this, as they can unweight the skis sufficiently to keep them from starting to carve until they are ready, then subtly re-establish pressure when the time is right. (In a full pendulum swing, the same racer described above now tunes his slalom skis with zero base edge bevel. He can now carve earlier in the turn, but must be extremely accurate in his movements as his skis hook up so suddenly and vigorously.)

Side Edge Bevel--primarily controls edge grip; more bevel grips better

• Optimal bevel: skis hold well on hard snow, but not so aggressively that they cannot be steered or feathered into a skid when needed.
• More bevel: skis hold better on harder snow, may bite too aggressively on softer snow.
• More bevel: edge forms a more acute angle (less than 90 degrees); this makes it feel sharper, but it also makes it more fragile and dull more quickly. It's sharper, but you'll need to maintain and resharpen it more frequently to keep that edge.
• Less bevel: skis are easier to steer and skid, but do not hold well on hard snow.
• On very hard snow and ice, some side edge bevel is important for an additional reason; without it, the side of the edge can literally pry the edge of the ski out of its groove as the ski tips further. A graphic would make this concept easier to explain, but imagine driving a shovel into firm snow, and then prying down on the handle. The blade of the shovel pivots against the surface of the snow, prying the tip of the shovel out. Now imagine that the shovel blade is curved lengthwise, so that it leaves a hollow area underneath it when driven straight into the snow. Now you'll have to tip the handle down further before the shovel blade touches the snow surface and begins to pry the edge out. In effect, side edge bevel accomplishes the same thing, allowing the sharp edge to continue to cut into the ice as the ski tips further on edge.

(A few years ago, VailSnoPro and Cgeib put together a short PowerPoint presentation with some great animated graphics to explain these effects of bevel. Perhaps one of them might post some of those images here, if we're really nice!)

Many things affect "optimal" bevel, including ski construction, snow conditions, technical skill, and skier preference. Torsionally softer skis twist more when tipped on edge, effectively increasing base-edge bevel at the tip and tail, and may benefit from slightly less base edge bevel as a result. Softer snow conditions do not require such tenacious edge grip, and may suggest less side edge bevel. Very precise and skilled skiers can handle--and will probably prefer (in most conditions)--an aggressive tune with minimal base edge bevel (0-0.5 degree) and more side edge bevel (3+ degrees); less-skilled skiers would find this tune difficult to manage, and may do better with a less aggressive tune (0.7-1 degree base, 1-2 degree side).

0.7-1 degree base and 2 degree side edge bevel is a pretty standard tune for many skis. Most skiers will find that tune predictable and easy to manage, yet sufficiently grippy for most turns on reasonably firm conditions. (Of course, regardless of the bevels, skis must also be sharp if they are to hold well.) Many skis come this way, and many shops have their edging equipment set up this way by default. Your mileage may vary, as they say.

Many people seem to think that the manufacturer's tune is somehow a "recommended" tune for that particular ski, but I would not look at it that way. It's usually just a tune that they think most "typical" skiers will find easy to ski. Rather than worrying about "manufacturer's specs" or someone else's recommendations, I encourage you to go by feel, with the understanding of what different bevels do. Skis grabby and unpredictable? Add base bevel. Skis not holding well enough? Are they sharp? If so, add side edge bevel. Skis too grippy? Reduce side edge bevel.

Finally, remember that changing a bevel requires grinding away more metal from the edge. Unless you're a racer with free skis, I recommend finding a tune that you like and sticking with it. For what it's worth, I tune pretty much every ski I have at 0.5/3 (by convention, the base edge bevel is always stated first). I ski them that way in every condition. Sometimes I'm tempted to increase the side edge bevel when it's extremely firm, but I don't often do it.

Once you settle on a tune you like, I recommend getting a set of good bevel guides and a file and diamond stone or two. It doesn't take much to learn to use these basic tools to keep your edges in great condition. Unless you cause some real damage, five minutes a day with a diamond stone will usually be all it takes to maintain your tune, and your skiing will be much happier for it!

“Turn right, turn left, repeat as necessary.”

 

[skibob]

Found this on the internet, credited to Epic but without an author. I'll just drop it here.



Base Edge Bevel--primarily controls "predictability" and how far a ski must be tipped before the edge engages

• Optimal bevel: Flat (unedged) ski is predictable, not "grabby"; skis are easily steered through the transition; edges engage smoothly but positively when appropriately tipped, and can still be "feathered" into a skid when needed.
• More bevel: Ski must be tipped further before the edge engages, allowing you to incline further into the turn before it hooks up and starts carving. Some strong skiers prefer this, especially those who prefer to stand fully on their skis with minimal "unweighting" through the transition, as they roll the skis from edge to edge. (This is rare, but I know a very strong racer who, for a while, tuned his slalom skis with a 3 degree base edge bevel, requiring him to move way inside the turn before the skis, which were then on a huge edge angle, started carving a very tight radius turn. The downside is later edge engagement; upside is incredibly tight carving radius when the edges finally do engage.)
• Too much bevel: flat skis are "swimmy" and do not feel like they'll hold very well, because you have to tip them a long way to get them to grip.
• Less bevel: Ski edge engages quickly when minimally tipped: ski is less forgiving, and requires very accurate, precise, and consistent movements.
• Too little bevel: Ski is "grabby" and unforgiving, difficult to steer smoothly, and very uncomfortable when flat on the snow, and "catching an edge" is more likely when skidding or sideslipping.
• Too little bevel: ski wants to hook up too quickly, trying to carve before you are sufficiently inside the turn for balance; the sensation is that the ski keeps coming back underneath you as you try to roll it onto edge to carve. Strong skiers with sophisticated pressure management skills may prefer this, as they can unweight the skis sufficiently to keep them from starting to carve until they are ready, then subtly re-establish pressure when the time is right. (In a full pendulum swing, the same racer described above now tunes his slalom skis with zero base edge bevel. He can now carve earlier in the turn, but must be extremely accurate in his movements as his skis hook up so suddenly and vigorously.)

Side Edge Bevel--primarily controls edge grip; more bevel grips better

• Optimal bevel: skis hold well on hard snow, but not so aggressively that they cannot be steered or feathered into a skid when needed.
• More bevel: skis hold better on harder snow, may bite too aggressively on softer snow.
• More bevel: edge forms a more acute angle (less than 90 degrees); this makes it feel sharper, but it also makes it more fragile and dull more quickly. It's sharper, but you'll need to maintain and resharpen it more frequently to keep that edge.
• Less bevel: skis are easier to steer and skid, but do not hold well on hard snow.
• On very hard snow and ice, some side edge bevel is important for an additional reason; without it, the side of the edge can literally pry the edge of the ski out of its groove as the ski tips further. A graphic would make this concept easier to explain, but imagine driving a shovel into firm snow, and then prying down on the handle. The blade of the shovel pivots against the surface of the snow, prying the tip of the shovel out. Now imagine that the shovel blade is curved lengthwise, so that it leaves a hollow area underneath it when driven straight into the snow. Now you'll have to tip the handle down further before the shovel blade touches the snow surface and begins to pry the edge out. In effect, side edge bevel accomplishes the same thing, allowing the sharp edge to continue to cut into the ice as the ski tips further on edge.

(A few years ago, VailSnoPro and Cgeib put together a short PowerPoint presentation with some great animated graphics to explain these effects of bevel. Perhaps one of them might post some of those images here, if we're really nice!)

Many things affect "optimal" bevel, including ski construction, snow conditions, technical skill, and skier preference. Torsionally softer skis twist more when tipped on edge, effectively increasing base-edge bevel at the tip and tail, and may benefit from slightly less base edge bevel as a result. Softer snow conditions do not require such tenacious edge grip, and may suggest less side edge bevel. Very precise and skilled skiers can handle--and will probably prefer (in most conditions)--an aggressive tune with minimal base edge bevel (0-0.5 degree) and more side edge bevel (3+ degrees); less-skilled skiers would find this tune difficult to manage, and may do better with a less aggressive tune (0.7-1 degree base, 1-2 degree side).

0.7-1 degree base and 2 degree side edge bevel is a pretty standard tune for many skis. Most skiers will find that tune predictable and easy to manage, yet sufficiently grippy for most turns on reasonably firm conditions. (Of course, regardless of the bevels, skis must also be sharp if they are to hold well.) Many skis come this way, and many shops have their edging equipment set up this way by default. Your mileage may vary, as they say.

Many people seem to think that the manufacturer's tune is somehow a "recommended" tune for that particular ski, but I would not look at it that way. It's usually just a tune that they think most "typical" skiers will find easy to ski. Rather than worrying about "manufacturer's specs" or someone else's recommendations, I encourage you to go by feel, with the understanding of what different bevels do. Skis grabby and unpredictable? Add base bevel. Skis not holding well enough? Are they sharp? If so, add side edge bevel. Skis too grippy? Reduce side edge bevel.

Finally, remember that changing a bevel requires grinding away more metal from the edge. Unless you're a racer with free skis, I recommend finding a tune that you like and sticking with it. For what it's worth, I tune pretty much every ski I have at 0.5/3 (by convention, the base edge bevel is always stated first). I ski them that way in every condition. Sometimes I'm tempted to increase the side edge bevel when it's extremely firm, but I don't often do it.

Once you settle on a tune you like, I recommend getting a set of good bevel guides and a file and diamond stone or two. It doesn't take much to learn to use these basic tools to keep your edges in great condition. Unless you cause some real damage, five minutes a day with a diamond stone will usually be all it takes to maintain your tune, and your skiing will be much happier for it!

“Turn right, turn left, repeat as necessary.”

paging @Chris Geib to the commentary phone . . .

 

[Sibhusky]

That was Bob Barnes.

 

[razie]

Good write-up.

Not sure why it says that the optimal base bevel would be flat(unedged)...?

 

[Eleeski]

Good write-up.

Not sure why it says that the optimal base bevel would be flat(unedged)...?

Because that's what I like!

 

[ScottB]

Good write-up.

Not sure why it says that the optimal base bevel would be flat(unedged)...?

He is not saying 0 deg is the optimal base bevel. He is saying when you have the optimal base bevel (TBD) and your ski is flat on the snow, it will behave like ...................

 

[Sibhusky]

Right, he doesn't mean the ski itself is flat. He means WHEN the position of the ski relative to the snow is flat it behaves like this, etc. I've had problems with that wording every time I've read it. Once I reread it, then I get it.

 

[James]

I didn't see the quote, but Bob and Chis Geib like basically no base bevel. I see he says 0.5. Well, that's his "all mountain tune".

I once put a 1/2 degree base bevel on Geib's ski... We were skiing polished manmade at Snowmass. It hadn't snowed in quite sometime. The ski, a Hart Phoenix, had no or almost no base bevel. So, I put a half on it. I've never heard the end of how I ruined his ski. That was almost ten years ago.

 

[oldschoolskier]

Several important item missed:

• Net side bevel, as it is what determines how well a ski bites into the ice. A 2 base with a 2 side is only net 0 vs a 1 base with a 3 side is a net 2. Which do you think will hold better?
• Ski construction and intent. A race tuned beginner ski won’t hold, a beginner tuned race ski will feel crappy. Tune must match the ski!

 

[Brian Finch]

I’ve been considering going to 1-1.5 on the base from .5 to get further inside & lesser hooky.... thoughts?

 

[skibob]

I’ve been considering going to 1-1.5 on the base from .5 to get further inside & lesser hooky.... thoughts?

Curious: What does "further inside" mean in this context?

 

[CalG]

I can only wish to get back to a flat base angle after about 20 days on any ski. When the skis go for the mid season base grind, I just ask to go FLAT no base bevel at all. Sometimes that just about gets the edges cleaned up. Machine made snow is tough on bases and edges.

Bottom line, I just ski them, some are better than others, I have lots to choose from ;-)

 

[James]

I’ve been considering going to 1-1.5 on the base from .5 to get further inside & lesser hooky.... thoughts?

Slarve the butter!

 

[Chris Geib]

paging @Chris Geib to the commentary phone . . .

Hi skibob,

I don't know that I have much to add to what Bob has written I didn't actually read this though I expect I did back when Bob posted it on Epic, but Bob and I have discussed the topic at length numerous times ...including @James need to detune skis from end-to-end!

What I would stress related to tuning is that in my opinion skis should be tuned after hours of skiing - not days, not weeks, not months, not seasons, but after each day ...or more frequently if warranted! Might be exception to the rule if conditions are such that the metal parts don't matter at all, but no harm in touching them up since you're going to have them on the bench anyway to wax them

It is usually pretty easy to keep everything in top notch condition with a little care routinely.

Here's a link to a post including a PDF version of the PPT Bob refers to.

The attached file is a PDF of a power point Ric & I did back in 2005 for an ESA presentation. Covers the general ideas. The power point is animated, but I apparently cannot upload that here and not immediately sure how to make it into something that will play...

 

[Brian Finch]

^

Curious: What does "further inside" mean in this context?

Torso inside of the skis in the turn

 

[Chris Geib]

Curious: What does "further inside" mean in this context?

"Generally" the base bevel determines how quickly the ski will engage as you move across the skis, through neutral, and into the new turn. Less bevel and they engage sooner; more bevel they engage later. Less bevel requires greater precision on the part of skier and can result in the ski engaging and beginning to turn before the skier is ready, thus before they have moved into a strong enough position to manage the centripetal forces underfoot. That is generally...

Other pieces parts such as boot setup, the ski construction and geometry, and of course the skiers ability and touch all play a part. It would be perfectly valid to prefer a different tune for a different ski, and skiers with strong canting may revolt against an aggressive base bevel for example.

So, Brian is looking to experiment with more bevel so that the ski is delayed a bit in engagement as he transitions and moves into the new turn, so that he is able to move farther across and into the new turn before the skis comes on strongly with the next impulse he is looking for.

 

[James]

View attachment 72749

Torso inside of the skis in the turn

Attempting a Polish Donut?

 

[Brian Finch]

"Generally" the base bevel determines how quickly the ski will engage as you move across the skis, through neutral, and into the new turn. Less bevel and they engage sooner; more bevel they engage later. Less bevel requires greater precision on the part of skier and can result in the ski engaging and beginning to turn before the skier is ready, thus before they have moved into a strong enough position to manage the centripetal forces underfoot. That is generally...

Other pieces parts such as boot setup, the ski construction and geometry, and of course the skiers ability and touch all play a part. It would be perfectly valid to prefer a different tune for a different ski, and skiers with strong canting may revolt against an aggressive base bevel for example.

So, Brian is looking to experiment with more bevel so that the ski is delayed a bit in engagement as he transitions and moves into the new turn, so that he is able to move further across and into the new turn before the skis comes on strongly with the next impulse he is looking for.

I generally run 0.5 / 3 & have forever, yet am amazed at how while at speed my skis tend to feel twitchy & in need of constant steering, while I see others ‘straight lining without a care’ with lesser skill/form.

 

[Brian Finch]

Attempting a Polish Donut?

I’ve been playing with drifting & sliding on my hip as a method of advancing my will on the slope.

 

[James]

I’ve been playing with drifting & sliding on my hip as a method of advancing my will on the slope.

That's good, so if you spin around on the hip, then pop up, keep going the way you were going, that's the Polish Donut. Right now you're just a donut hole.