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11/17/2021 Mind the Heel Gap

Londoners and Dynafit binding owners tend to be very mindful of gaps. The city-folk are reminded to look out for the gap between train and platform when stepping onto the tube (British for subway). The ski-folk needs to keep an eye on the gap between the back of their ski boots and the heel towers of tech bindings. These are important since forgetting either can lead to falling on one’s face. In this article, we will focus more on ski binding heel gap than the type that can be found underground.

Tech binding heel gaps have been present since the original pin-style bindings were designed by Fritz Barthel in the early 1980s. Unlike most alpine bindings, the toe and heel units on current models of lightweight backcountry bindings do not slide forward or backward when under pressure. That means another mechanism is required to allow skis to flex naturally. This problem was solved with metal heel pins that are designed to slide in and out of tech fittings on a ski boot. By placing a gap between the heel tower and ski boot, tolerance was added for skis to flex as the pins can dive deeper into the boot.

The question is, how much gap should there be between the boot and heel unit? Or asked another way, how much should the metal pins slide into your boot? If there is too small of a gap, the metal pins become fully inserted into the boot and the heel tower itself collides with the boot. This can prevent the release mechanism of the binding from working properly. If the heel gap is too large, your release values might end up on the low side causing pre-release and the aforementioned face plant. In extreme cases when the ski is flexed in reverse, say when picking up your foot lodged in deep snow, the pins can pull out from your boot completely. Therefore, it’s crucial for optimum performance of tech bindings to have the gap configured correctly.

The first step in ensuring you have the right heel gap is knowing the manufacturer's specifications. Luckily, the gaps have become fairly standardized and there are only a few sizes from which to choose. Here are the details:

ATK Heel Gaps
Candy / Crest 4mm
Haute Route 4mm
Raider / Freeraider 4mm
Revolution / Trofeo 4mm
Atomic Binding Heel Gaps
Backland Tour 4mm
Black Diamond Heel Gaps
Helio (all) 4mm
Dynafit Binding Heel Gaps
Low Tech Race 1 & 2 4mm
RC1 4mm
Expedition 4mm
Superlite 150 5.5mm
Superlite 1 & 2 / 175 5.5mm
Speed / SpeedFit 5.5mm
Speed Turn 1 & 2 5.5mm
Speed Radical 5.5mm
Radical ST / FT 5.5mm
Radical 2.0 0.1mm
Rotation 10 / 12 / 14 0.1mm
Rotation 7 / Lite 5.5mm
Vertical ST / FT 5.5mm
Fritschi Heel Gaps
Vipec / Evo 1mm
Xenic 1mm
Fischer Heel Gaps
Tour Race 1, 2 & 3 4mm
G3 Heel Gaps
ION (all) 0mm
ZED 9 / 12 0mm
Grizzly Heel Gaps
GR 98 4mm
Olympic 4mm
Marker Heel Gaps
Alpinist 0mm
Plum Binding Heel Gaps
Race (all) 4mm
Oazo / Pika / WEPA 4mm
Guide / Yak 4mm
Summit 4mm
Salomon Binding Heel Gaps
MTN 4mm
Ski Trab Binding Heel Gaps
TR-Race / Adjustable 4mm
Gara Titan 4mm
Titan Vario / Release 5mm
Titan Vario.2 0.75mm
Hagan Binding Heel Gaps
Core / Core Pro 4mm
Ride / Pure 4mm
Ultra / ZR 4mm
La Sportiva Binding Heel Gaps
RSR / RST 4mm
Kreuzspitze Binding Heel Gaps
EL 6mm
RS / RS-A 6mm
SCTT / SCTTT 6mm
GT / GT 2.0 6mm
Slatnar Binding Heel Gaps
ST Touring 1mm

So how do you set the heel gap correctly? That mostly depends on whether your heel piece has a fore/aft adjustment mechanism. If the heel does not adjust, you have a race binding and it needs to be mounted precisely for your boot. Binding manufacturers provide their dealers with jigs designed to make setting this gap a snap, though with manufacturing tolerances you can't blindly trust them. We specialize in fixed race mounts at Skimo Co and have custom tools and processes to ensure accuracy. This means that, uniquely, we can guarantee a precise race mount.

Adjustable bindings, on the other hand, let you work with various boot sole lengths. Ranges of 20mm to 40mm of adjustment are typical. With Dynafit touring bindings, a few twists with a Pozidriv screwdriver will set your gap, though a flathead will do in a pinch. For Trab adjustable bindings, a socket wrench may be needed. Plum includes a mini Torx key with their adjustable bindings. Whichever the tool, you will have some flexibility when it comes to changing boots and a margin for error when mounting by hand.

To help measure the heel gap, some manufacturers include various shims that approximate their specified heel gaps. These should slide snugly between the boot and the heel housing. For adjustable bindings, you can tune the fore/aft settings with the shim in place until it fits. See below for a sampling of the shims that might ship with your bindings.

If you do not have a shim, various arrangements of pocket change will do the trick. Two unworn nickels measure just under 4mm, and adding a quarter will approximate the 5.5mm gap. Alternatively, a cheap set of metric hex keys makes a great heel spacer kit.

In conclusion, it is important to be mindful of your tech binding heel gap, sometimes referred to as the “tech gap”. You should only need to set it once per boot configuration, but please make sure it is as close to manufacturer spec as you can get it. If you would like more frequent reminders of gap dangers, we recommend a sightseeing tour of the London underground.

This article was originally published on 12/26/2013 and was last updated on 11/17/2021.

Comments

1/31/2024
Comment from JenL
 
My Dynafits ST10's are 3 years old and I have a little play in the heel pins, is this normal? I hadn't noticed it before but both binding have it.
Reply to this comment:

1/26/2024
Comment from Emily
 
Hi, thanks for this info! We recently purchased a binding that the shop called "Fischer/ dynafit tour classic 10" -- do you know if this is the same as Dynafit ST Rotation 10? If so, the heel gap should be very minimal, right? It was mounted with a couple mm of gap. Thanks!
1/26/2024
Reply from jbo
 
Hi Emily, the ones we've seen were Radical 2.0s which is a 0.1mm gap.
Reply to this comment:

1/18/2024
Comment from Richard Tomlinson
 
Hi, I’ve had Dynafit rotation 10 lite fitted to my skis and had a premature heel release yesterday. The din setting is correct. The heel gap was set at 5mm. Your chart quotes 1mm. Is this correct for the lite version? At 1mm my Scarpa Maestrale boots foul the heel tower in touring mode so I’ve backed off the gap to about 1.5 to get clearance when the ski is flexed. Am I missing something? I’d appreciate your advice.
1/18/2024
Reply from jbo
 
Hi Richard, I'm not aware of a Rotation 10 Lite binding. The Rotation 7 Lite uses a 5.5mm gap whereas the Rotation 10 is the 0.1 kiss gap. Feel free to send a photo of your bindings to help@skimo.co for help with identification.
Reply to this comment:

10/25/2023
Comment from Nic
 
Every shop I have worked in posts this list up on the wall. It would be awesome if you all had a printable, or excel, version of this :)
Reply to this comment:

3/5/2023
Comment from Steffen
 
Hi, I have the ST Rotaion 14, and can't seem to find information regarding the heel gap anywhere. I got the local shop to install the bindings, but the gap feel a bit snug. What is the correct heel gap for this binding?
3/5/2023
Reply from jbo
 
Hi Steffen, it is the same as the Rotation 10 & 12, or about the thickness of a piece of paper.
Reply to this comment:

12/2/2022
Comment from Steffen
 
I have 3 pairs of G4 Zed12s. If I don't leave >1.5mm gap then walking becomes a nuisance as the rotated heal piece (pins pointed away from boot) clips the rear of the boot, creating a snagging sensation while walking.
12/3/2022
Reply from jbo
 
Hi Steffen, there are a few bindings whose flat mode doesn't work great at the specified heel gap when traversing soft snow on soft skis or navigating dips and such. For example, ATK recommends increasing the gap if that that scenario is going to be a priority. Please note changing a heel gap will affect your release values which you may want to correct for.
Reply to this comment:

10/12/2022
Comment from Chuck
 
Hi all,
I just bought a pair of used demo dynafit ski with a radical st binding. The tech set the gap at 5mm but i am getting a heel release of 121nm and 134nm instead of the recommended 229nm.
Could the demo style binding (on slide plate) change the gap setting?
Is it ok to close up the gap until i get the 229nm release or is that a bad idea?
11/3/2022
Reply from Teddy Young
 
Hey Chuck, the gap should be 5.5mm for a Radical ST and 0.1mm for a Radical ST 2.0/Rotation, send us a photo if you'd like us to double-check the binding model!

The gap should remain the same, but you can adjust the release value screws in order to dial in the release, as the RV numbers on the heel housing may not be perfectly calibrated.
Reply to this comment:

4/19/2022
Comment from Alex
 
Does the 5.5 mm for speed radical cover all generations of this binding? Or does the 2021 speed radical fall in the 2.0 category?
4/19/2022
Reply from jbo
 
Hi Alex, that is all generations!
Reply to this comment:

3/19/2022
Comment from Andy
 
I just got some new boots, and have marker alpinists. Unfortunately since I sized down my boot, I have a ~2mm gap now (limit of adjustment). Think this is ok to ski? Or would you recommend a remount?
3/19/2022
Reply from jbo
 
Hi Andy, officially we'll have to recommend a remount. Unofficially...maybe some easy skiing only.
3/19/2022
Reply from Andy K
 
Fair enough! Thanks for the quick response
Reply to this comment:

3/12/2022
Comment from salar
 
Why such a big difference between the two different kinds of dynafits?
Reply to this comment:

12/29/2021
Comment from Ben
 
I have a pair of Ski Trab Titan Vario 1 bindings, but they are mounted with the ATK adjustment heelplate, not the bulky Ski Trab heelplate that comes with the bindings. Since I am mounting these heels "race style" should I have a 4mm gap like the Gara Titan or a 5mm gap as is recommended for the Vario 1?
12/29/2021
Reply from jbo
 
Hi Ben, the Vario 1s need a 5mm gap, whether fixed mounted or on any plate. It's quite a nice distance that enables flat mode to work well also.
Reply to this comment:

1/8/2021
Comment from Jerry
 
I just bought a pair of 2020 Dynastar Speed Turn 2.0 bindings. the Dynastar website recommends a 4mm gap, rather than the 5.5mm recommended here. Why the difference?
1/8/2021
Reply from jbo
 
Hi Jerry, sounds like an error by Dynastar.
1/8/2021
Reply from Jerry S
 
OK, thank you very much
Reply to this comment:

11/18/2020
Comment from Peter
 
Just got new boots and I'm curious: how strict is the 0mm recommendation on the G3 ion? The shop that mounted them (and adjusted to the old boot) left about 2mm, and the 0mm gap now seems to provide a little resistance stepping in. Ok to split the difference? Unknowingly skied the 2mm gap for 3 years (shoulder shrug)
11/18/2020
Reply from jbo
 
Oops Peter, that is a bit wide. But yes, we have slightly opened the gap to help with step in on some occasions (altering the rubber sole can also help) and it hasn't caused any notable issues.
Reply to this comment:

10/25/2020
Comment from Steve
 
Why does Rotation 7 have a 5.5mm gap, while Rotation 10 has a 0.15 gap? Seems odd since they are both based on the Radical 2.0, right?
10/25/2020
Reply from jbo
 
Hi Steve, the 7 pairs the rotating toe from the 2.0 with the original Radical (1.0) heel.
Reply to this comment:

3/13/2020
Comment from Erik Sandelin
 
Recently bought a pair of new skis with new dynafit st rotation 10 and the heelgap adjusted to 0.15mm as above. After two very shorts runs the heelgap is now roughly 4-5mm on both. Ever encountered this behaviour? Is it related to the 10mm "travel" of the bindning?
3/13/2020
Reply from jbo
 
Hi Erik, that doesn't sound good! You can notice some travel when stepping in if the brakes get hung up on the boots, but that isn't a permanent change. You may have something broken in the baseplates.
3/14/2020
Reply from Erik S
 
I realise that i overestimated the gap When looking from above. The increase is not 4-5mm but still slightly lager than paperwidth. I also got the feeling the gap had decreased somewhat a couple of hours later. I am gonna a do a more careful experiment to be sure of ny observations :-)
Reply to this comment:

12/4/2019
Comment from Brendan
 
After skiing around 5000 feet of brutal suncups, I came to find that both my boots had somehow forced themselves down past the pins on my Kreuzspitze GT heels units. They were flat on ski, and the pins were gouged into the plastic pretty good. I had set the gap carefully at 6mm. I've used this setup quite a bit, and never otherwise had this problem, but also never skied such an undulating surface for so long. I'm wondering how to avoid this. should I consider shortening the gap?
12/4/2019
Reply from jbo
 
Hi Brendan, that's not good. You can close the gap 1mm to help if you plan on skiing a lot of suncups! Also, we convinced them to lengthen the heel pins a bit since the 2016 version you have; we have some that we could send you that are 1mm longer. It would require some binding surgery to install.
Reply to this comment:

11/7/2019
Comment from David Stevens
 
Am I right in thinking Dynafit Rotation ST10 bindings have a minimal 0.15mm heel gap?
11/7/2019
Reply from jbo
 
Hi David, that's right! You should be able to slip a piece of paper in there but that's about it.
Reply to this comment:

1/22/2019
Comment from Marc H
 
Hey guys, do you know the gap of the old Dynafit Tour Lite Tech heel? It's grey, blue and red with a metal post as the high riser? I assume its 4mm, but the pins are quite short and there's a plastic nub that protrudes between the heel pins. Thanks.
11/7/2019
Reply from jbo
 
Hi Marc, most of those older "classic" bindings were 4mm. I can't be certain without a photo, but you're likely correct.
Reply to this comment:

11/4/2016
Comment from Jakob
 
Hi, I have a pair of Hagan ZR Bindings mounted with a 4mm gap. Now I am thinking about switching to new boots with a 2 mm shorter BSL which would mean a 6mm gap (assuming accurate measurements and a similar distance from the front edge to the toe inserts). I read somewhere that some people mount the ATK race bindings with the 5.5 mm gap to be able to rotate the heal 90° for a flat position. If 5.5mm works I am guessing 6mm will be fine without a remount as well. Does anyone have experiences with that?
11/4/2016
Reply from jbo
 
Hi Jakob, the official BSL marks aren't perfectly reliable when calculating precise heel gaps. That said, it is likely possible you can ski at a 6mm gap, noting the release value will be very different and you may need to adjust accordingly (style or locked vs unlocked).
Reply to this comment:

3/17/2016
Comment from Martin
 
Hi, thanks for the article. I recently purchased Dynafit Radical 2.0. In my mind the shop has set them to the traditional 5.5 mm gap. Is there a way to check/change the gap to the exact specs? I am worried if I just start guesstimating when trying to reduce the gap to 0.14
3/17/2016
Reply from jbo
 
Hi Martin, you can clamp a piece of paper (~0.1mm) between the boot and heel, then back up the heel until it falls out.
Reply to this comment:



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