Dynafit Tech Note — Radical FT Heelpiece Spring 2013/2014

Post by WildSnow.com blogger | April 9, 2014      

This year the Dynafit Radical has a small but significant change from previous years’ bindings. The binding includes a tiny spring in the heel assembly in order to provide a small amount of forward pressure.

Forward pressure is one of several features that make traditional alpine ski bindings better than tech bindings, when it comes to going down. Forward pressure actively holds the boot in the binding, while still allowing the ski to flex as well as helping “pre load” the binding toe for elasticity and safety release. Dynafit bindings on the other hand simply allow the boot to slide on the heel pins a small amount in order to allow for ski flex. Unfortunately this only allows the ski to flex a certain amount, and if you boot goes past the limit, you’ll quite possible get a pre-release when your boot heel bangs into the binding heel unit. This has always been one of the drawbacks of tech bindings, and in my opinion causes a fair amount of Dynafit pre-releases.

I’ve been skiing on the new spring-loaded Dynafit binding since December, and have put quite a few days on them. When testing first began, we noticed that the heel piece moves back a small amount every step uphill, due to the spring compressing. My initial thought was that it could be a potential concern for wear and tear on the binding (and of course uses a tiny amount of energy every step). Obvious course of action was to test the binding vigorously, which I’ve been diligently doing through numerous ski trips. A few days ago I took apart the binding to check for possible wear. The binding looked quite good, almost as good as new.

The radical heelpiece viewed from underneath. Note the spring (denoted by red arrow). Also, note minimal wear in areas that would be suspected.

The Radical heelpiece viewed from underneath. Note the spring (denoted by red arrow). Also, note minimal wear in areas that would be suspected.

The binding includes this thin steel plate to be placed under the heelpiece. It allows the unit to move back and forth on a smooth surface. This most likely prevents the wear you might expect.

The binding includes this thin steel plate to be placed under the heelpiece. It allows the unit to move back and forth on a smooth surface. This most likely prevents the wear you might expect. Grease helps.

Otherwise, the binding has been performing just as smoothly as past Dynafit Radicals. I ski with fairly stiff skis and I’m a light guy, so I don’t “bottom out” Dynafit bindings in the way that this feature is supposed to prevent, therefore I can’t comment much on its effectiveness. One other minor issue to note: the spring can easily be bottomed out if the binding is adjusted all the way to its shortest length setting (editor’s note, Louie, is that what you mean for sure?). This will not necessarily affect the normal binding functions, however it will make the spring useless, negating this feature of the binding and could be a concern for larger aggressive skiers.


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19 Responses to “Dynafit Tech Note — Radical FT Heelpiece Spring 2013/2014”

  1. Rob April 9th, 2014 2:11 pm

    My radical FTs with the new spring have developed significant slop of the heel post in relation to the base plate/BSL screw. To the point it’s unpleasant to ski on them and I fear the possibility of catastrophic failure

    I just got some new baseplates this week to try and remedy issue (if only temporarily) they seem to be in exceedingly short supply.

    A friend’s radicals have developed same issue after less than a full season of use.

    It’s the first real issue I’ve had with any dynafit binding after many hundreds of days of use… disappointing.

  2. Lou Dawson April 9th, 2014 5:45 pm

    Rob, when Louie and I saw how the binding moved with every step uphill, we suspected that thousands of cycles would perhaps cause a wear problem. I asked Louie to post what he found, and he found no significant wear after quite a bit of use. Apparently you had the opposite experience.

    The first question, how much did you ski the bindings? How much resort and backcountry?

    Second question, was the stainless steel plate installed under the heel post, as shown in Louie’s post?

    Third question, after you install new parts, could you please please report back after enough use to evaluate wear issues?

    Thanks, Lou

  3. Louie III April 9th, 2014 6:44 pm

    Rob – thanks for the comment! I was wondering if anyone else would experience any issues (even though I didn’t). If you have any pictures of it you want to send, feel free to email them to pub836 (at) wildsnow

  4. See April 9th, 2014 7:23 pm

    I wonder if the new design makes it less obvious if the binding is set up with too little space between binding and boot heel. If the gap were too small, I can imagine how there would be excessive movement/wear of the binding heel due to ski flex induced movement of the entire heel piece instead of just the pins sliding in and out of the boot heel. If the spring allows 6mm travel and the gap spec is 5.3 mm, theoretically one could probably get away with zero gap.

    (Also, I’m guessing the new gauge is meant to solve the problem of damage to old feeler gauge caused by adjusting the heel piece too close to the boot with the gauge in place. The old gauge is easy to squash, rendering it useless.)

  5. carol April 9th, 2014 10:40 pm

    i have the same problem with my new radical ST’s that Rob noted. A fair amount of slop after only 20 days or so of skiing. There was initially a bit of movement on one binding, but now on both, and seems to be getting progressively worse. The ski tech took one apart and didn’t notice any obvious wear. His thought is that its partly the pins and partly because the post is halfway along the adjustment rail. I’m a small person, and not an agressive skier, so I’m really surprised that the bindings are deveoping this extra movement.
    Lou – do you know if dynafit plans on making changes to the design for next season?

  6. Gogi April 10th, 2014 4:45 am

    I also experienced plenty of heel slop with this new heelpiece, and Dynafit sent me a pair of new sliding plates when I contacted them about it (https://www.flickr.com/photos/119337308@N03/13264906153/). They are supposed to help reduce the slop, but I don’t know if they actually do, since I haven’t installed them.

  7. Lou Dawson April 10th, 2014 6:41 am

    It is significant that Louie and I did not have any trouble with these issues. In fact, based on my bench research I expected a problem might develop and was in part surprised (and of course delighted) when it did not. But based on feedback I’m getting, yes, it appears this version of Radical is somehow more prone to play.

    It appears the plate in some cases needs to be shimmed up a bit off the ski so it supports the center spindle of the heel unit. Any competent binding mechanic should be able to do this in their sleep, using a bit of duct tape. Beyond that, it appears the new binding is more sensitive to tiny amounts of “screw jacking” wherein the heel unit sits ever so slightly above the ski top due to bulging of the screw holes or double threading of the screws in the plastic base.

    Oh, and there is always the possibility that the binding mech just plain forgot to install the gliding plate — since earlier Dynafit bindings did not have the plate (though all tech bindings should have support under the heel spindle post, in my opinion, as I’ve seen plenty of skis with damage to the top skin under where the center post rests.)

    I’m not viewing this as a big problem as it seems easy to cure, but I’d offer that all binding makers really should be more careful about naming their bindings. When a binding receives a significant design change such as this, it should be renamed in some way, and perhaps have a small (or large) change in appearance. That would help mechanics and DIY folks to know they need to pay attention to possible problem points that didn’t exist with previous versions.

    Lastly, all ski bindings have play. Don’t obsess on it. Excessive play should of course be fixed (it sounds like Gogi and others do need to fix their bindings), but eliminating all play by jamming parts of the binding or setting it too tight is not going to instantly transform you into a TGR movie star.


  8. Rob April 10th, 2014 11:00 am

    I’ll try and get some photos or video to you Louie. But the heel slop and skiing experience is at worn out fritschi toe (and perhaps approaching Naxo levels)

    My original new in box bindings did not come with the stainless plate.

    I was somewhat surprised when I saw the new ones had it. Don’t see that it can prevent anything other than topsheet damage since it lifts the whole base plate, spindle and all, off the ski? Hence the “high tech” new duct tape version? Which would seem likely to be ruined as soon as BSL is adjusted?

    Anyone matched a Vertical Heel with a Radical toe? scew pattern is the same, right? Wouldn’t radical toe also help out with ramp angle?

  9. Lou Dawson April 10th, 2014 11:47 am

    Rob, the tape shim is supposed to go _under_ the plate, raising it up a bit under the heel spindle post. You are correct about the glide plate lifting whole base. I wrote about that faster than I could think (grin), and will edit to prevent confusion. On the other hand, the plate could exacerbate screw jacking and disguise any problems with the binding heel unit not being screwed as tightly as possible to the ski. Oh, AND IF THE GLIDE PLATE IS NOT INSTALLED the bottom of the spindle is going to wear into the top of the ski as it moves, this alone could quickly cause obvious play, as some skis have quite a bit of soft stuff on the top surface that could quickly wallow out. In your case, that would most certainly be something to look for, and something that installing the shimmed plate will compensate for (and if not, add more duct tape!).

    I can’t imagine that Dynafit intended the binding to be used or installed without the plate. If it wasn’t in the box, that’s got to be a packaging mistake.

    Yes, you can use a Vertical Heel with a Radical toe, or just get an earlier model Radical without the spring “feature.” I actually still prefer the Vertical models, and even earlier.

    Most of the bindings next year do have what I view could be an important improvement, with the toe having a turntable function. This will put an end to issues with boot toe fittings being sticky. But it could have some unintended consequences. A top engineer once told me that in any machine, you can NOT change ANYTHING without it affecting something else — frequently in unexpected ways.

    Have to admit I’m chuckling about repairing a $500 binding with duct tape. But then, I just fixed a new pair of skins with bailing wire. I guess we’re still in the dark ages?


  10. Rob April 10th, 2014 12:37 pm

    Thanks Lou that makes sense.

    I’ve skied these skis quite a lot this season 30-40 days in bounds and touring. But nothing different than I’ve done with pairs of Verticals and Comforts which now have many hundreds of days on them without any signs of wear or deterioration in performance.

    While the radical’s heel post flipper is a reasonably pleasant convenience the anti rotation feature was a cure to a problem that never really existed IMHO. And the resulting difficulty in returning to ski mode while staying clicked in for efficient transitions was certainly not worth paying the price for.

  11. James July 24th, 2014 8:00 pm

    After only three days of touring my new FTs have a lot of play in the heel piece both in ski and tour mode.
    Like everyone else on this blog, I´m very suprised (and disappointed) as my old Dynafits are still rock solid after more than 10 years of hard skiing.
    If I wasn´t in South America I would certainly return them.
    For now the only option is the duct tape shim under the plate (thanks for the tip Lou) and if that is not enough, I´ll try to fabricate a slightly thicker plate.
    Dynafit needs to deal with this problem ASAP.

  12. James July 26th, 2014 2:57 pm

    It feels funny contributing to this blog at a time when all of you in the northern hemisphere are in flip flops with binding issues as the last thing on your mind. When I pulled the bindings I found I had quite a bit of screw jacking from the metal plate that could have been part of problem. When I mounted the bindings the first time I had redrilled those holes (another crucial tip from Lou) but apparently not large enough. I took the skis for a spin today with the duct tape shim and the heel posts seem to have held up with only a minor bit of play. Thanks again for all the beta!

  13. Lou Dawson July 26th, 2014 7:58 pm

    James, we are global, seriously. Lou

  14. Shane January 20th, 2015 10:11 am

    Any word on if the heel play issue was resolved for the 2014-15 radicals?

  15. Piotr February 16th, 2015 1:15 am

    I also have issues with significant play in the heel unit.
    Any update on that? Does the duck tape “fix” really help long-term?

    I guess I can try to do it myself, but I’m wondering how much tape do I need to put there…

  16. Lou Dawson 2 February 16th, 2015 1:29 am

    Shane, our pair of 2014-2015 do not have this problem and as far as I know it is fixed. Lou

  17. James February 17th, 2015 5:46 am

    If you remove the bindings, use a sharp chisel to shave off the ski material that most likely came up with the screw threads from the initial mounting and redrill the thin metal plate large enough so the screws don´t grab it and then remount with one piece of duct tape shim, then you should be good to go. My heel pieces held up fine for the rest of the season. One of the Dynafit skier/designers (I happened to run into him at the pub, the people at the office never got back to me) confirmed to me that the problem is indeed a result of screw jacking from the metal plate. Dynafit intentionally made the screw holes smaller so they would hold the plate on to the binding for a neat ¨ready to install¨ package.

  18. Kam Harris January 9th, 2017 10:01 am

    Has anybody noticed a lack of rebound in this spring? I was touring yesterday and found that one of my heels was sticking in the compressed mode, causing me to occasionaly prerelease in the heels.

  19. Kam Harris January 9th, 2017 4:03 pm

    found out it was a stripped adjustment screw

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