Binding Ramp Angle - Measuring the boot board and toe shims?

[tinyrobotman]

Last season I picked up a pair of Technica Zero G Tour Pro boots for my touring skis which are mounted with G3 Ion bindings. When skiing either of my touring skis, ON3P Steeple 108 or Volkl BMT92 I have the sensation that the front of the ski is unstable, wanders, and is knocked around easily, especially in manky snow. My guess is I'm not able to keep proper pressure on the tip during the turn. My alpine setup is an ON3P Billygoat (118 underfoot) with Marker Barons and Lange RS130 boots. This setup feels 100% balanced and I wouldn't change a thing. The Steeple is essentially a narrower touring version of the Billygoat so should ski similarly and the boots are both 130 flex, 4 buckle so shouldn't be a huge difference there either. The other day I got curious about the binding/boot ramp angle. With the skis flat on a level floor I put an electronic level in the boot and measured the ramp of the boot board with the boot in the binding. The Lange in the Baron measured out at 4 degrees, which is exactly what Lange states the boot board ramp on the RS130 is. So that means the Baron is flat. Next, I measured the Technicas in the Ions the same way and came up with right about 7 degrees of ramp.

First, could this 3 degrees of additional ramp angle be causing my wandering tips and lack of fore/aft balance compared to the alpine setup? If so it seems like shimming the binding toe would be the way to go. However some quick math with a measured 300mm between the front and back pins I would need a 15.7mm toe shim to bring the Technica's down to the total 4 degree ramp I have with the alpine setup. That seems huge?!

 

[Noodler]

Assuming you measured the net ramp angles correctly, 3* is a massive difference and can very well be at least part of your predicament. What is your BSL?

 

[ted]

Yes this situation can easily be a ramp angle issue.

You are dealing with two different variables- the boot board ramp angle/forward lean and the binding delta.

The boot affects the ankle foot anatomy and the binding delta affects more proximal anatomy,

As far as the boot it is hard to compare the internal ramp as one has an alpine sole and one has a rubber sole of unknown external dimensions.
Also the location of the pins vertically can vary from boot to boot. How do the boots feel standing on a flat floor Do the tecnicas feel different? If not, For starters, I would simplify things and ignore the boot ramp for now and shim the toes of your bindings. The binding delta is more likely to be the issue.

This is a very helpful article-

Binding Pin Heights

A handy reference table detailing the pin heights on various tech bindings. This is useful when determining the approximate ramp angle at which you will be skiing and skinning.

skimo.co

How much? Agree 15 cm seems huge, probably stat with the mm shims here-

B&D Shims

Getting the right ramp angle on your bindings can make the difference between skiing on-point or in the backseat with tired quads. B&D makes shims for almost every occasion. Choose a shim based on your binding and desired pin height delta, which can t...

skimo.co

Don't forget you need to get longer screws.

 

[ted]

Also, checkth binding mount point as it is another variable, Area the Steeples and Billy Goats mounted the same.

 

[Noodler]

Yes this situation can easily be a ramp angle issue.

You are dealing with two different variables- the boot board ramp angle/forward lean and the binding delta.

The boot affects the ankle foot anatomy and the binding delta affects more proximal anatomy,

As far as the boot it is hard to compare the internal ramp as one has an alpine sole and one has a rubber sole of unknown external dimensions.
Also the location of the pins vertically can vary from boot to boot. How do the boots feel standing on a flat floor Do the tecnicas feel different? If not, For starters, I would simplify things and ignore the boot ramp for now and shim the toes of your bindings. The binding delta is more likely to be the issue.

This is a very helpful article-

Binding Pin Heights

A handy reference table detailing the pin heights on various tech bindings. This is useful when determining the approximate ramp angle at which you will be skiing and skinning.

skimo.co

How much? Agree 15 cm seems huge, probably stat with the mm shims here-

B&D Shims

Getting the right ramp angle on your bindings can make the difference between skiing on-point or in the backseat with tired quads. B&D makes shims for almost every occasion. Choose a shim based on your binding and desired pin height delta, which can t...

skimo.co

Don't forget you need to get longer screws.

This is why I specifically stated NET ramp angle in my post. Net ramp is the summation of bootboard ramp + binding delta. It's the actual resultant ramp that we ski on. This is easily measured using a digital inclinometer that has a "hold" function. Measure the net ramp with the boot in the binding and the liner pulled out so that the inclinometer can rest across the heel and toe sections of the bootboard.

This is a very critical angle in fore/aft stance alignment. Even without an inclinometer, I recommend that skiers test this angle themselves while indoors. Put your skis on a flat floor (hopefully it's truly level), pop your boots into the bindings (without the liners), then put your footbeds into the shells directly on top of the bootboards. Slip your feet into the shells and see how your fore/aft balance feels. I find it helpful to have a long mirror off to the side to see where your knees are aligned over your boot toes and to see the relative amount of flex in your joints. It's important to keep your leg evenly positioned between the front and back of the boot cuff (since the liner isn't present).

Before I got my fore/aft alignment figured out, I found that I was definitely overly pitched forward in all of my setups. I have since rectified that by incorporating 3mm toe lifts (gas pedal) on my boots, reducing the bootboard ramp angles to 2*, and changing all of my binding deltas to 2.0mm. Now I no longer have to guess about what's going to happen to my fore/aft balance when I go skiing.

 

[tinyrobotman]

Thanks for all the great info. It seems to confirm what I suspected. As Noodler said the net ramp angle would be the key measurement. That's what I was reading with the digital level (a Bosch precision construction level) on the boot board with the boot in the binding with the ski flat on a level floor. The skis are both mounted on the line so I don't think that's a factor.

I began to suspect the ramp angle the other day after skiing both setups in the same day. I toured in the morning and then went to the resort in the afternoon and immediately noticed that the alpine setup felt much more balanced and natural. Almost all the variables besides the ramp angle were similar. That is snow, skis, boot stiffness, visibility, mood

Since these are pin bindings shimming the toe on the binding is the only option. At my work I have a CNC router and some HDPE plastic so I can make shims of any thickness I need. However it seem that the availability.of longer binding screws might be the limit to toe shim thickness? I'm only finding 21mm flat head binding screws at the longest. Not to mention the leverage issues with longer screws.

 

[Scruffy]

Thanks for all the great info. It seems to confirm what I suspected. As Noodler said the net ramp angle would be the key measurement. That's what I was reading with the digital level (a Bosch precision construction level) on the boot board with the boot in the binding with the ski flat on a level floor. The skis are both mounted on the line so I don't think that's a factor.

I began to suspect the ramp angle the other day after skiing both setups in the same day. I toured in the morning and then went to the resort in the afternoon and immediately noticed that the alpine setup felt much more balanced and natural. Almost all the variables besides the ramp angle were similar. That is snow, skis, boot stiffness, visibility, mood

Since these are pin bindings shimming the toe on the binding is the only option. At my work I have a CNC router and some HDPE plastic so I can make shims of any thickness I need. However it seem that the availability.of longer binding screws might be the limit to toe shim thickness? I'm only finding 21mm flat head binding screws at the longest. Not to mention the leverage issues with longer screws.

You can plane the boot board down to decrease the board ramp angle.

 

[Noodler]

You can plane the boot board down to decrease the board ramp angle.

What @tinyrobotman is dealing with is more complex than just the bootboard ramp angle. Changing the binding delta (which is outside of the boot) impacts both the net ramp angle and the effective forward lean when skiing. Note that the bootboard ramp angle has no bearing on the forward lean. The forward lean of the shell cuff is what positions the angle of your lower leg. The angle formed between the boot cuff and the bootboard must be matched to the skier's available dorsiflexion RoM. Tipping the entire boot back/forward, either via sole plating or binding delta changes, is what achieves the fore/aft stance alignment (in the sagittal plane). You could also potentially alter the forward lean of the boot for improved stance alignment, but the ability to do so is highly dependent on the specific boot model you're dealing with.

 

[ted]

Thanks for all the great info. It seems to confirm what I suspected. As Noodler said the net ramp angle would be the key measurement. That's what I was reading with the digital level (a Bosch precision construction level) on the boot board with the boot in the binding with the ski flat on a level floor. The skis are both mounted on the line so I don't think that's a factor.

I began to suspect the ramp angle the other day after skiing both setups in the same day. I toured in the morning and then went to the resort in the afternoon and immediately noticed that the alpine setup felt much more balanced and natural. Almost all the variables besides the ramp angle were similar. That is snow, skis, boot stiffness, visibility, mood

Since these are pin bindings shimming the toe on the binding is the only option. At my work I have a CNC router and some HDPE plastic so I can make shims of any thickness I need. However it seem that the availability.of longer binding screws might be the limit to toe shim thickness? I'm only finding 21mm flat head binding screws at the longest. Not to mention the leverage issues with longer screws.

Most ski shops have a bowl of old binding screws. Longer screws came on older bindings that had big lift plates. Also check Slidewright, he sells individual screws. IIRC wintersteiger also has 28mm flat tops.

Since you have the CNC capability you could make a mounting plate similar to the ones found here-

Tech Binding Parts & Accessories

skimo.co

Which would eliminate he binding screw length issue.

I haven't had shear problems with longer screws, but as I skied leather tele boots for a long time, I have a light touch on the snow.

 

[ted]

What @tinyrobotman is dealing with is more complex than just the bootboard ramp angle. Changing the binding delta (which is outside of the boot) impacts both the net ramp angle and the effective forward lean when skiing. Note that the bootboard ramp angle has no bearing on the forward lean. The forward lean of the shell cuff is what positions the angle of your lower leg. The angle formed between the boot cuff and the bootboard must be matched to the skier's available dorsiflexion RoM. Tipping the entire boot back/forward, either via sole plating or binding delta changes, is what achieves the fore/aft stance alignment (in the sagittal plane). You could also potentially alter the forward lean of the boot for improved stance alignment, but the ability to do so is highly dependent on the specific boot model you're dealing with.

+1
And as the Tecnica boot board ramp is difficult to measure accurately due to the non standard sole, I'd get the binding ramp right first and then try to deal with the boot ramp if it is still an issue. Unless Tecnica is can share that info with you.

 

[ted]

Tecnica rabbit hole-

Tecnica ZeroG Tour Pro - 2018- 9 boot

1300g! 12-13deg forward lean https://www.powder.com/gear-locker/tecnica-goes-light-bright-updated-zero-g-boot/?sm_id=organic_fb_social_PWDR_180126_sf180360900#sf180360900...

www.tetongravity.com

Ramp angle may be buried in there. Also Wasatchback guy that posts there is a Tecnica rep.

 

[cantunamunch]

Since you have the CNC capability you could make a mounting plate similar to the ones found here-

Tech Binding Parts & Accessories

skimo.co

Which would eliminate he binding screw length issue.

As someone who went down ^this rabbit hole several times over the years, there are knock-on issues to tall (12-18mm) toe plates.

First, if you don't taper the toe plate, you will cause a pressure point on the boot lug that will eff with binding release.

Second, the toe plate creates a hinge point in the ski flex, immediately in front of the binding.

Third, the boot apparent flex becomes stiffer (more apparent force for the same turn pressure) and slower (less direct, i.e. bigger motions required).

It was fun to play with. But very, very, very far from a free lunch.

 

[Noodler]

+1
And as the Tecnica boot board ramp is difficult to measure accurately due to the non standard sole, I'd get the binding ramp right first and then try to deal with the boot ramp if it is still an issue. Unless Tecnica is can share that info with you.

I didn't mention the other challenge in modifying the bootboard ramp angle is that the "volume" of the bootboard is inextricably tied to the fit of the boot. So if the height of the bootboard is reduced, you will be changing the boot fit. This is why I recommend resolving stance alignment either before, or in conjunction with, finalizing the boot fit.

 

[tinyrobotman]

Exactly, I'd rather not mess with the fit on the boot until I have the external factor of the binding figured out. Plus 15mm of boot board grinding won't leave me with a boot board anymore I can adjust the cuff if need be after I fix the binding ramp. The overall fit of the Tecnica is pretty good, still working on my usual issue of getting enough big toe room (I have a comically large big toe compared to the rest of my foot), but it's a solid start.

Since the touring boot is essentially suspended on the pins the sole shape will make no difference in what the NET boot board angle is when in the binding. The net angle is what I believe and that what I'm measuring with the inclinometer?

cantunamunch I'm guessing I won't have the release issues since the toe is a tech toe. I assume you're talking about alpine bindings or did you have issues with high risers on pins? Also not planning on making the plate any longer than the original toe piece footprint so shouldn't have hinge point issues. I could reverse ramp the toe shim on the CNC to keep the binding at the same apparent angle to the boot as before but that seems overly complicated and would mean the screws wouldn't sit flat.

Also, not sure how the toe shim affects the apparent flex? With the shim I should be engaging the cuff from a more upright stance, but that should make things more responsive not less?

I think I'll find some of the 28mm screws and then mill the plate based on how much screw thread I need sticking out. Might not be able to get a full 15.7mm plate but pretty close. I Will report back.

I didn't mention the other challenge in modifying the bootboard ramp angle is that the "volume" of the bootboard is inextricably tied to the fit of the boot. So if the height of the bootboard is reduced, you will be changing the boot fit. This is why I recommend resolving stance alignment either before, or in conjunction with, finalizing the boot fit.

 

[cantunamunch]

cantunamunch I'm guessing I won't have the release issues since the toe is a tech toe. I assume you're talking about alpine bindings or did you have issues with high risers on pins?

It's more of an issue with pins since you're preloading the bottom of the pin slot. Smaller contact surface area than an alpine lug AND a metal on metal contact.

With alpine, we care less. Especially with Salomon Driver toepieces since the contact area is enormous compared to tech bindings.

Also not planning on making the plate any longer than the original toe piece footprint so shouldn't have hinge point issues.

That's exactly how you DO create the hinge point. Forward pressure has a longer moment arm to rotate around and press into the ski. In order to get rid of the hinging, you have to taper the plate forwards, beyond the original contact zone.

(And to adhere it to the top of the ski, so ski flex doesn't lever the lower screws off. VHB tapes are useful here, just like were used on original Derbyflex and EPB plates.)

I could reverse ramp the toe shim on the CNC to keep the binding at the same apparent angle to the boot as before but that seems overly complicated and would mean the screws wouldn't sit flat.

I'm not sure we have quite same structure in mind.

In my plate structure, the lower screws are perfectly flat to the original ski surface. The binding screws are perfectly flat to the plate surface. 8 screws total per toepiece. No problem.

Obviously, my 'plates' were wood/fiberglass composite (cut off portions of older skis, with epoxied metal to hold the bottom tier of screws) and capable of holding binding screws - not HDPE.

Also, not sure how the toe shim affects the apparent <boot> flex?

<edit mine - ctm>

By making the cuff shaft more vertical in the sagittal plane, you cannot start flexing the boot with just your body weight. You have to move the CoM forward relative to your toes to do that. This makes the boot apparently stiffer, especially in subtle centering moves.

With the shim I should be engaging the cuff from a more upright stance, but that should make things more responsive not less?

More net force at the *end* of the flex; less immediate feedback from the ski at the start of flex. Which of those is the word 'responsive' referring to here? I can interpret it either way.

 

[Scruffy]

What @tinyrobotman is dealing with is more complex than just the bootboard ramp angle. Changing the binding delta (which is outside of the boot) impacts both the net ramp angle and the effective forward lean when skiing. Note that the bootboard ramp angle has no bearing on the forward lean. The forward lean of the shell cuff is what positions the angle of your lower leg. The angle formed between the boot cuff and the bootboard must be matched to the skier's available dorsiflexion RoM. Tipping the entire boot back/forward, either via sole plating or binding delta changes, is what achieves the fore/aft stance alignment (in the sagittal plane). You could also potentially alter the forward lean of the boot for improved stance alignment, but the ability to do so is highly dependent on the specific boot model you're dealing with.

Of course.

The forward lean of his two boots are about the same 12* for the Lang, 12-13* for the ZeroG. If the the boot board ramp is higher in ZeroG, he his starting from more open stance ( more planter flexed) Boot boards are something easy to play around with.

But, all this may be moot anyway - it seems the boot board ramp is 3.5 for the ZeroG, so the binding delta may be the only issue.

If OP's math is correct, I'd be concerned with a 1/2" lift in the toe only on those bindings. There are pins in the heel as well, as with @cantunamunch 's concern for a tapered toe lift plate, I'd think a tapered plate in the heel might be warranted for proper pin alignment. Or, perhaps a one piece tapered plate. In fact a one piece tapered plate would be easy to make, mount and experiment with different reverse ramp angles without changing anything else.

 

[tinyrobotman]

Ok, this is starting to make my head hurt. However, skiing both setups back to back again yesterday the Tecnica/Ion setup doesn't feel right so I definitely want to make some changes. I guess the question is, is the taper shim on the heal piece needed? At what point will I run into issues with the rear pins being out of angle enough to cause problems?

 

[cantunamunch]

No discouragement intended. I might, though, suggest taking small, incremental steps (that can be reversed) and using convergent approaches.

As in: try small ~4 mm shims under the toe to start. Ski that, then tweak the bootboard or do a spoiler.