NOTE: We’ve found that many skiers think bindings have one ramp or delta angle that can be expressed in degrees. In other words, we hear people asking things like “what is the ramp angle of that binding, 12 degrees?” One of the most important concepts in ski binding ergonomics is this: If your boot and your foot inside the boot are not at a somewhat level position while in the binding, you do have a binding “ramp” or “delta” angle. ONLY… THIS ANGLE CHANGES AS YOUR BOOT GETS LONGER OR SHORTER.
Now, before we are excoriated by marketing people who like to spout off with binding ramp angles, we’d guess that when you do hear things like “that binding has an 8 degree ramp,” that’s probably measured with the standard industry size sample boot, generally a size 27.
Main takeaway, beyond basic like or dislike of steeper binding ramp angles, many touring bindings do have significant ramp and skiers with shorter feet may experience incredibly exaggerated forward (heel higher) ramp. Solution is to be aware of what you’re buying (use the chart below), but also know that it’s quite easy to shim up the toe of most tech bindings using various DIY or aftermarket parts. (That said, be aware that stacking the binding toe will result in a corresponding reduction of climbing heel lifter “height.”)
Spreadsheet below has angles calculated using different boot lengths. Note those angles were calculated after adding 2 millimeters to the boot heel height to compensate for the position of the tech fittings in most boots. (I also include a Fritschi Freeride frame binding for reference, with inserted “average” boot measured to the centers of the tech binding fittings plus 2 mm at heel. Likewise, I did a rough calculation of how an imaginary boot with a fairly flat ramp would look on the chart. Both those examples are at the bottom of the list.) To scroll the chart horizontally, if you can’t see the incredible disappearing Google horizontal scrollbar, place mouse pointer on chart, left click, drag mouse pointer to left and right border.
Spreadsheet above, ski binding delta (ramp) numbers. Note, we’re trying to adhere to a convention here in calling the binding angle “delta” and the angle created by the inside of the ski boot we will call the “ramp.” We are gradually editing past articles to that effect. If we’re talking about the combined delta and ramp angles, we’ll probably call it “combined ramp angle.”
Know that due to how tech bindings such as Dynafit function, the spreadsheet numbers are not the binding delta/ramp as you would measure with an alpine binding. Instead, they are the distance from ski top up to the center of tech binding pins. Thus, the numbers are for COMPARISON between different ski touring tech bindings. (We do have some angles calculated in the spreadsheet, for specific boot sole length and with a few mm added to the heel fitting height to make the results more reflective of real life.)
For real-world concept, know a couple of things: For most tech bindings to provide the somewhat “neutral” or “zero” ramp of a zero angled alpine ski binding, you’d have to raise the boot toe up quite a bit, sometimes a centimeter or so. That’s a huge amount, and enough to cancel out much of your climbing lift. Instead we’re working with smaller increments, and tend to use the old TLT binding delta (or a bit less) as our baseline goal. My measurements are accurate to within a half mm or so, all to the centers of pins both toe and heel.
In my view, earlier TLT Dynafit binding model had the ideal delta. Measured in the way illustrated it's about 4 degrees for a smaller to average length backcountry skiing boot. Bear in mind that talking about delta angle in degrees is confusing, as the longer the boot the less 'angle' though the stack height of the toe and heel remain the same. Thus, in this blog post I talk more about stack height differences between toe and heel than 'degrees.' There is no industry standard for measuring binding delta angle, but you can sure feel it!
Radical mod with a Radical binding, shimmed with B&D plate for neutral to negative ramp. If you have time time experiment, worth a go.
My favorite delta angle is equal to or a bit less than the original Dynafit TLT models: heel of boot is stacked about a centimeter higher than toe. What I like about this configuration is it gives some forward lean power to ski boots that are otherwise quite “flat” and may walk comfortably but need a bit more lean when latched in the binding and headed downhill.
All fine and dandy…but, you can have too much ramp and lean for today’s style of skiing. The ramp of the earlier TLT bindings could be considered excessive. Later Dynafit models such as Comfort, Vertical and Radical added even more height at the heel and in many people’s opinions most certainly have too much ramp. Other brands of tech bindings tend to have quite a bit of ramp as well, though you’ll find choices in toe shims that reduce ramp (such as with some configurations of Plum bindings.)
Personally, I like a more relaxed skiing stance; less tippy-toe 1970s herky jerk — more Stephen Drake. Furthermore, I’m sick of jumping from ski to ski and adjusting to different ramp angles, so I’m standardizing my quiver at the TLT angle or a bit less. That way my in-house skis will all feel familiar, and when I’m at demos I’ll still be used to some ramp and won’t get thrown forward when I step into an unshimmed pair of Dynafit Radicals or other ‘rampy’ tech bindings.
Lets go over the shim stack thickness requirements I got from a digital caliper session in the WildSnow shop (these could be a tiny bit different than previous blog posts, due to how measured, but such small variations make no practical difference for real world ramp-angle tuning). Below ARE DONE AS A COMPARISON TO TLT AS BASELINE. (Actually specifying the exact ramp angle of a binding involves how it interacts with a given boot length, see spreadsheet above.)
So, Dynafit older TLT models are my baseline. But they have an obvious ramp angle of boot heel higher than boot toe. If you want virtually neutral ramp add about 3 mm to the shim thicknesses I list below. Bear in mind that as you shim up the toe on tech bindings, you cause an equal reduction in the height of your climbing heel lifters. Along with their toe shim plates as shown in the photos here, B&D ski gear sells some solutions for that (see photo below).
Dynafit Vertical ST/FT, Comfort, shim toe up about 5 mm to equal same as TLT, or go thicker for neutral ramp.
— Recommendation: Use B&D shims.
Radical ST/FT, and Speed, shim toe up 3 mm to equal same as TLT, or go to virtually neutral ramp by adding thicker.
— Recommendations: Custom made 4 mm shim, or for virtually neutral ramp use 6.5 mm FT/ST toe plate with Speed model, or B&D shim plate with Radical FT/ST.
(Note, I measured difference in heel/toe heights as accurately as possible on Radical and early TLT, most accurate difference I could come up with is that Radical has 2.84 mm more heel height than TLT, so round that up to 3 mm)
B&D shim plate with front and rear tabs you add on to support various binding model toe-base shapes. This 6.5 mm shim changes Dynafit Comfort and Vertical model ramp angles to equal that of older model TLT, which in my view is ideal. If used with Radical models, you'll end up with a virtually neutral ramp angle that might be too reduced. Note the variety of screw holes to accomodate nearly all tech binding brands and models.
Early Dynafit Comfort toe unit on B&D shim equals ramp of TLT . Without shim, ramp angle is excessive enough to damage knees.
Radical FT (left) and ST toe plates (OEM) appear to be different thicknesses. Would be proof God exists if one was thicker than the other and could be used as a shim, but alas, in support of the agnostics amongst us they're both only 6.3 mm thick in support of the binding. To equal the old TLT form factor you'd need another 3 mm of toe lift. Or 4+ mm if you want to start getting into the 'no ramp' zone. To that end, I easily found a poly cutting board that's 4.85 mm and could be cut into shims.
One of the easiest ramp shim mods is to use the base plate (and longer screws) from a Radical ST toe to produce nearly zero (flat) ramp angle for a Dynafit Speed, which uses the same toe unit as Radical ST/FT. A B&D plate works for this as well, but doesn't look as 'factory.' Dynafit and B&D plates are virtually the same dimension plus-minus 6.5 mm. This mod would definitly require B&D 'Nubbins' to raise the heel lift height.
B&D Ski Gear sells 'Nubbins' that raise Dynafit Radical heel climbing height by 6 mm, easily compensating for most shim mods. Or use with stock binding for more climbing lift. B&D also has longer 'volcanoes' for the Comfort model bindings. Bear in mind that use of climbing lift extension places more leverage on the binding. I thus don't recommend them for larger skiers carrrying big loads such as during a Denali expedition.
Gorilla in the room is your screw lengths. For example, add a 3 mm shim and you need 3 mm longer screws. A couple of solutions.
1. B&D sells longer screws to go along with their 6.5 mm shim plates. If you shim to 3 mm, you can order these screws and cut the tips off (grind down and re-sharpen).
2. The longer B&D screws also work for stacking their plates with Radical bindings.
3. When shimming the Dynafit Speed model, simply use screws specified for Radical models.
4. If you’re a total DIY, you can use generic wood screws to mount bindings. Get best match at hardware store and cut to length. If necessary trim diameter of head by chucking the screw into a drill and running against a file or sanding block. Torque carefully and use epoxy.
5. With thinner skis, always check ski thickness vs screw length by using calipers. Trim screws that are even a hair too long to avoid risk of ski damage.
Ergonomics: Ski style, foot size and more will change your perception of binding ramp changes. If you are primarily doing muscle powered skiing, I recommend smaller changes in ramp angle. If you do a lot of mechanized laps and thus have ample time to experiment, try everything you can. Bear in mind that the Dynafit binding models with the most excessive ramp are the Vertical FT/ST and the Comfort. These bindings are what inspired B&D to make their shims, which drop the FT/ST/Comfort ramp back to that of the TLT. Along with that, know that the shorter the boot the more ramp angle for a given stack height difference between toe and heel — hence folks with small feet may experience the most detriment from rampy bindings. Lastly, skiers with multiple skis to choose from will benefit by standardizing their binding ramp angle.
Shop here for B&D products. The shim plates weigh 30 grams (1 ounce) without the front and rear tabs, which weigh 8 and 12 grams respectively.
Below is info for the Dynafit OEM Radical binding toe plates, available from dealers or direct from Salewa NA. Both plates are the same thickness, ST plate recommended for stack shimming.
ITEM DESCRIPTION ITEM #
FRONT BASE PLATE (SPACER) ST 48580 9999 $15.00 (30 grams, has reinforcing web underneath, recommended)
FRONT BASE PLATE (SPACER) FT 48581 9999 $20.00 (28 grams, hollow underneath for vibration damper)
WildSnow.com publisher emeritus and founder Lou (Louis Dawson) has a 50+ years career in climbing, backcountry skiing and ski mountaineering. He was the first person in history to ski down all 54 Colorado 14,000-foot peaks, has authored numerous books about about backcountry skiing, and has skied from the summit of Denali in Alaska, North America’s highest mountain.
