Testing La Sportiva Hybrid Trab Tech Fittings

Post by WildSnow.com blogger | September 12, 2016      

See our review comparing Sportiva Spectre 1.0 and 2.0

So, boys and girls, we lashed up this rig using the G3 ION as it provides consistent release and noticeably more clamping  pressure than most other bindings, which makes them easier to test.,

So, boys and girls, we lashed up this rig using the G3 ION as it provides consistent release, and noticeably more clamping pressure than most other bindings, which makes them work well as a test bed. And yes that’s a real “force gauge” measurement instrument. As engineer Cam Shute of G3 says, “Don’t talk about it unless you can measure it.” I used this unit as a “push” gauge, with only my muscle power and a slide platform made from plexiglass to reduce friction. The heel of the boot is held by an anti-friction shim at the same level as if latched in downhill mode. Much of the variation in my data sets is no doubt due to using poorly regulated muscle power to push the gauge, but my results had obvious consistencies so I didn’t trouble with creating a mechanical force injector. BEAR IN MIND, this test was performed WITHOUT THE HEEL LATCHED to measure retention tension of the toe unit presumably related to the shape of the boot toe tech fittings.

The ski touring rumor factory: You could banshee scream “IT’s ALIVE” and you wouldn’t be far off the mark. As with any gossip, do not trust — verify like crazy before you base your credit card I/O or personal safety on what you hear muttered over the digi-waves. Today, case in point. Folks are questioning the performance of La Sportiva’s “hybrid” “tech-Trab” fittings (used in their Spectra 2.0 boot and others), designed to function with both “standard” tech bindings as well as Trab’s Attaco TR2. (Note, Trab has truly interesting bindings, check them out.)

If Albert Einstein was a freeride tour skier, he’d call the “TechTrab” fittings genius. Firstly, don’t fret whatsoever on the heel fittings. For a tech binding, they’re identical. It’s the toe where potential weirdness resides like an imaginary alien gray hovering over your sleeping form, contemplating an abduction for experimental shenanigans. Not to worry. Where the Trabuchian smarts come in is the Trab toe fittings test out beautifully. Smooth lateral release, no sticking or catching. According to our testing they do yield slightly less release resistance, on the order of a half a DIN number or so. For those of you who tend to dial up your settings, unnoticeable. But if you do precision DIN settings, be aware you’ll want to bump up your lateral tension a hair. Or better, as always, throw your skis on a test machine and see what your settings are actually yielding (reminder number 462: “DIN” numbers printed on ski bindings are just an approximation, for roughly setting release values “RV” before testing.)

Macro comparo señorio.

Macro comparo señorio. Trab managed to make their fittings nearly identical to Dynafit’s in terms of release and retention performance. Lack of the Dynafit “Quick Step In” lead notch is not a deal breaker for ski touring, though the Quick Step is a nice feature for noobs. In our opinion, what makes the Trab offer slightly less toe retention is the tiny amount of additional ramp on the fitting, as shown above. That’s just a theory. I did measure the toe pin insertion depth of the ION, Sportiva came in at 92.03 mm wing width, with Dynafit new boot at 91.9, so they’re virtually identical at four tenths of a millimeter difference, which we assume is within manufacturing tolerances.

Also be aware that this slight reduction in retention force at the toe will influence how easily you can backcountry tour with your binding toes unlocked (something we enjoy doing with ION, for example). Indeed, while the percentage difference in release force is minimal when you’re in downhill mode, it’s more significant in touring mode where going unlocked with an ION might give you enough retention with a fully Dynafit clone toe fitting, but enough less retention with Spectre to result in you bending at the waist and locking them up, for the up.

Spreadsheet below. Don’t be alarmed by the percentage differences. Remember this is only for the toe, nearly all retention and release tension with a classic tech binding is provided by the heel. Again, our numbers indicate that while doing precision setting of release values you’ll want to increase your lateral release settings for Sportiva-Trab fittings at most 1/2 a DIN number. (And remember the heel fittings are identical in performance, so no change in vertical release.)

Also regarding the spreadsheet, please know that the “DIN” number is an approximation, as DIN is based on boot sole length and our 24 centimeter faux sole length is down on the lowest end of the DIN charts. On our favorite chart, a “twist” force of 20/23/26 Nm is DIN 2.5 with a ~24 centimeter boot sole. I used 24 centimeters as my push point as it resulted in enough force for my gauge to respond well, around halfway in the test instrument range of 0-200 Newtons. Pushing farther back towards the heel of the boot results in a longer lever arm and an easier test release, which I felt was too “loosy goosy” for my force gauge.

(If I’m off base when it comes to this DIN information, I’ll edit immediately, am waiting for confirmation from a mechanical engineer friend of mine.)

In summary, during bench testing the La Sportiva hybrid “trab-tech” toe fittings allowed smooth lateral release with no grabbing or sticking. They had around 1/2 a DIN number less retention than our sampling of other tech fittings, so if you’re fine tuning consider dialing up your lateral release setting accordingly. Those of you who bottom out your release settings or use higher ranges clearly need not make any changes, as the the higher your heel DIN settings are the percentage difference of toes becomes an influence too small to be a factor, in my opinion.

La Sportiva Spectre 2.0 is easily one of the better power-weight ratio shoes out there.

La Sportiva Spectre 2.0 is easily one of the better power-weight ratio shoes out there. This pair of 27.5 weights 1474 grams (52 ounces) per boot. You can remove the lower buckle, power strap and Trab heel fittings (if you don’t use Trab bindings) to trick out for big vertical uphill. We liked and reviewed Spectre 1.0, and like this one even better.


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17 Responses to “Testing La Sportiva Hybrid Trab Tech Fittings”

  1. Pablo September 12th, 2016 9:54 am

    It would be nice to see also in this comparo the Amer Group Fittings (Atomic Backland ans Salo MTN)

  2. cam shute September 12th, 2016 3:18 pm

    nice post lou!!

  3. Lou Dawson 2 September 12th, 2016 3:36 pm

    Thanks Cam, ready to get scolded here… did I calc the Nm torque correctly for a 24 cm lever arm? Torque = .024 * Newtons ?


  4. Andrew September 12th, 2016 4:08 pm

    Too many zeros. It’s 0.24m

  5. Lou Dawson 2 September 12th, 2016 4:51 pm

    Yeah, but doesn’t that make the torque in Nm come out wrong?

  6. Lou Dawson 2 September 12th, 2016 5:05 pm

    Andrew, yeah, you’re right, using the correct decimal place results in correct torque, then the decimal is shifted over for a “DIN” number. So for example 25 Nm would be a DIN of 2.5, or something like that anyway… Cam?

  7. Lou Dawson 2 September 12th, 2016 5:56 pm

    Ha, I knew I had the DIN vs torque info somewhere. Check out quote from Fritz Barthel in this article:


    He says “…E.g., a setting of “8” for the lateral release would mean that a torque of 80 Nm on the boot should open the binding (plus/minus some tolerance)…”

    So it looks like I’m on the right track in the spreadsheet, basically that if you want to fine tune, perhaps dial up bindings about 1/2 a DIN number in lateral release if you’re using the Trab fittings.

  8. See September 12th, 2016 8:10 pm

    Thanks, Lou. Excellent, as usual. I’m hoping Wildsnow will do some measured vertical release testing one of these days. Some quantitative information about bindings with fixed vertical release might be interesting, for example. My guess (based on zero experience) is that they have high release values. Also based on 0 experience, the Trab binding heel looks like it might have better elasticity and stiffness. So while the Trab boot heel fittings may be functionally equivalent to traditional pin heel fittings in traditional bindings, Trab binding heel may work better.

  9. Dabe September 13th, 2016 10:40 am

    thanks for showing LS some love! And making me feel good about getting a set of TLT binders for my Sideral 2.0s for this winter.

  10. Crazy Horse December 2nd, 2016 5:36 pm

    I usually prefer to shop locally, but I just discouvered my new favorite ski shop, in Spain of all places. I have a “difficult” foot shape— actually an impossible foot shape for most AT boot lasts. And I’m no bonus baby, so laying out $750 for a new pair of boots sends me running for the duct tape until I can’t forestall the inevitable.

    Much to my surprise, the La Sportiva in it’s current iteration is actually very roomy in the forefoot, accommodates my high instep, has a great walk mode, and is feather light. However it is priced $678 at every shop in the US.

    Barrabas, located up in the mountains in Spain sold it to me for $449 including $60 shipping! Even more amazing, they received my order on Monday morning and it was on my doorstep in Driggs Idaho Wednesday afternoon. Halfway around the world in less time than it usually takes to get an order from Salt Lake.

  11. swing January 6th, 2017 1:21 pm

    Hi there,
    you are doing really impressive tests.
    I have a question that nobody can answer, if someone can, it is you!

    I bought second hand ski and boots with no experience (you have to start one day…)
    My bindings are TLT radical while the boots are scarpa spirit tr2.
    I did not know about the TR2 bindings.
    Are these boots compatible with my bindings? I precise that the boot heel is compatible with both systems (regular low tech with 2 pin and the tr2), but I am not sure about the toes.
    I have read both answers on the web, but why put such a heel insert if you cannot use it? I am lost…

    Thank you for your help.

  12. Lou Dawson 2 January 6th, 2017 4:09 pm

    I have Spirit TR2 here in my hot little hands. I am looking at them right now. This pair has a plastic “filler” screwed onto the heel that’s clearly NOT compatible with a Dynafit Radical or other standard tech binding. The plastic filler can be removed and appears easily replaced with a steel part that IS compatible with Dynafit Radical.

    However, I’m not certain the Scarpa TR2 toe fittings are entirely compatible with Dynafit. They seem to function to some degree, but I’m not sure they have the exact correct shape. I was told back when this boot was released that it was NOT compatible with Dynafit.

    What may be confusing you is that newer boots made by La Sportiva, as I blog about above, are indeed compatible with both Trab and Dynafit.

    My recommendation would be to NOT use Scarpa TR2 with Dynafit bindings.


  13. swing January 7th, 2017 10:12 am

    Hi Lou,
    thanks for your answer. It is too sad because these boots fit me perfectly, and buying new TR2 bindings is so expensive.
    I am just discovering ski hardware the hard way!

    For info the boots had the heel compatible with low tech from origin.



    Have a nice winter 😉

  14. Lou Dawson 2 January 8th, 2017 7:21 am

    Hi Swing, sure, as shown in your photos some of the TR2 Scarpa boots had the heel fitting for Low Tech (Dynafit). They were probably samples, or perhaps sold in Europe. If you can find some, and they test on workbench to function in your Dynafit bindings, then fine. If those are your boots in the photos, and they have the heel fittings, then test them on workbench and perhaps use if they are evaluated to function correctly, to be as safe as possible.

    If you are not certain, then be careful. Perhaps save money with something less important to your personal well being.

    I tried to answer your question. The TR2 boots I have here do not have the Dynafit heel fittings, and the toe fittings in my opinion are not 100% compatible. The improved system, illustrated here in Sportiva boots, is 100% compatible with tech bindings (Dynafit, etc.) albeit perhaps needing slight adjustment to compensate.


  15. See January 8th, 2017 9:18 am

    At least one major US internet retailer is currently selling what appear to be Spirit TR2’s as “Dynafit compatible Spirit 3’s.”

  16. swing January 11th, 2017 12:52 pm

    Thanks again for your help. I just have to sell them now!
    BTW it finally snowed this week.

  17. Wynn January 23rd, 2019 11:16 am

    What does Rick Howell have to say?

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  • Welcome to Louis (Lou) Dawson's backcountry skiing information & opinion website. Lou's passion for the past 50 years has been alpinism, climbing, mountaineering and skiing -- along with all manner of outdoor recreation. He has authored numerous books and articles about ski touring and is well known as the first person to ski down all 54 of Colorado's 14,000-foot peaks, otherwise known as the Fourteeners! Books and free ski touring news and information here.

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