Forward lean, ramp angle, binding delta...

[Bruno Schull]

Hi Folks.

I'm positing this here, and not in the boots section, because bindings play a role.

I've been thinking about ways to use boot, footbed, boot boards, and binding adjustments to help keep my weight (more) forward when skiing.

There must be important difference between achieving a more forward position by increasing the lean angle of the boots (flexing your ankles foward) vs. modifying footbed and boot boards (lifting your heels) vs. playing around with bindings.

Before going any further, can we go over some terminology?

Forward lean--Something you can adjust on boots, for example, 15 or 17 degrees, and so on, which I assume describes the change from vertical. This can be adjusted with foam pads, and other liner modifications, to the shaft of the boot.

Boot delta--The difference between the top of the footbed at the heel and the toe. This seems like it would vary a great deal between manufacturers, between sizes, and so on. It can be adjusted by changing or modifying foot beds, by grinding boot boards, by adding shims under boot boards, and by playing around with the height of the heel and toe of a boot, by adding shims, or grinding material away.

Binding delta--The difference in height between the top surface of the binding at the heel and the toe where the boot rests. This can be adjusted with shims and what not.

Have I confused these? Where does ramp angle fit in? Does that usually describe boots, or bindings?

Thanks,

Bruno

 

[Philpug]

Boot delta--The difference between the top of the footbed at the heel and the toe. This seems like it would vary a great deal between manufacturers, between sizes, and so on. It can be adjusted by changing or modifying foot beds, by grinding boot boards, by adding shims under boot boards, and by playing around with the height of the heel and toe of a boot, by adding shims, or grinding material away.

Binding delta--The difference in height between the top surface of the binding at the heel and the toe where the boot rests. This can be adjusted with shims and what not.

What you are referring to Boot delta is Boot ramp.

As far as the bindings, if you go to the reviews section where I have the 2022 bindings, all list the toe and heel heights so you can compare them. It is a sticky at the top.

 

[dbostedo]

Forward lean--Something you can adjust on boots, for example, 15 or 17 degrees, and so on, which I assume describes the change from vertical. This can be adjusted with foam pads, and other liner modifications, to the shaft of the boot.

Two pieces to this one... the inherent/default forward lean of the boot itself, which you sometimes see listed. And the forward lean of your lower leg in the boot which could be pushed fore and aft by adjusting with liner modifications as you note.

For instance, the Lange RX100 has "Stance: 4° Ramp, 12° Forward Lean" (per thebootpro.net website). So the forward lean of the boot is 12°.

What I don't know is if the two add, to give the default angle with the ski or not. (I.e. if that boot is clipped into a ski with 0 binding delta, is the cuff at 12 degrees to the ski, or 16 degrees to the ski? I suspect 12 degrees.)

 

[cantunamunch]

Boot delta--The difference between the top of the footbed at the heel and the toe. This seems like it would vary a great deal between manufacturers, between sizes, and so on. It can be adjusted by changing or modifying foot beds, by grinding boot boards, by adding shims under boot boards, and by playing around with the height of the heel and toe of a boot, by adding shims, or grinding material away.

Changes to the outside of the shell absolutely do not belong in the same category as changes to the inside of the shell.

If you insist on lumping them together, you will get contradictory results and wind up chasing your own tail wrt cause and effect.

What I don't know is if the two add, to give the default angle with the ski or not. (I.e. if that boot is clipped into a ski with 0 binding delta, is the cuff at 12 degrees to the ski, or 16 degrees to the ski? I suspect 12 degrees.)

They do not add. They are separate pieces of information. You should totally do the Masterfit course.

 

[Rod9301]

More forward lean will cause you to stick your butt out to remain balanced.

It will not move your weight forward. You accomplish this by pulling your feet back

 

[Philpug]

More forward lean will cause you to stick your butt out to remain balanced.

Not necessarily. Lets avoid blanket statements.

 

[KingGrump]

Just to screw things up a bit.

Numbers are fine and dandy. The real test is when the rubber (plastic) hits the road (snow.)
Actual experience. Skied 2 pairs of Head and 3 pairs of Fischer with 14° forward lean over 15 years. Figured 14° is the optimal angle for me. Switch to pair of Atomic. Set it up at 14° at the shop. Felt totally lost on the hill. A thick spoiler made it much better. Resetting the cuff to 18° made it sing to me.

 

[Bruno Schull]

@ Philpug--thanks for the correction. So we have forward lean, boot ramp, and binding delta. So far so good.

It makes sense that changing these things have different effects, even if they might seem the same. For example, changing forward lean by adding a shim/spolier vs changing the position of lean on the shaft will ultimately feel different, even though they both achieve similar (but not identical) goals of increasing the angle of your lower leg from vertical.

Let the conversation continue!

 

[Wilhelmson]

I get a feeling that old time nordic boots mimicked regular hiking boots which had a higher heel height for traction and maybe uphill travel. Well at first they would have used the same boots they did for chopping wood, skiing, or ice fishing.

But now of course skiing has its own reasons for a higher heel, but it seems that more boots and maybe bindings are backing off the ramp a bit

 

[Henry]

Binding delta can be expressed either in millimeters of height difference between heel & toe or in degrees of slope angle. (Delta is shorthand for difference.) Keep in mind that the delta angle will vary as the size of the boot varies. For the same delta millimeter difference, a longer boot, in longer binding positioning, will result in a reduced delta angle vs. a shorter boot. A size 225 boot in a binding has more delta angle than a size 315 boot in the same make & model binding.

I've known a few skier alignment specialists who can get close to a skier's optimal balance position by looking at how they stand in boots. Observing a ski run then helps fine tune it. All I know is what feels good to me with my leg length, my leg to upper body lengths, my lower leg to upper leg lengths. I like more delta and more boot shaft angle (my current boots don't have removable boot boards) than some like. Some bindings work better for me with a 1/8" plexiglass shim under the heels; I feel balanced then. That's just me.

A fellow I've skied with has ankles with a congenital situation where they don't flex. He can't dorsiflex his ankles and is always back on his heels. To get him balanced and centered over his skis he needs the boot ramp angle increased and in some cases the heel bindings shimmed up. That's just him.

If your boots have cuff angle adjusters on both the inside and outside of the cuff, see if, after you get the cuff angle set for your legs, there is adjustment range remaining in both adjusters. If so, you can turn both equally up or down to change the cuff shaft angle without changing the side-to-side angle.

There is no One Size Fits Most.