Does anyone love the dynafits ramp angle?

[andybrnr]

Really didn't like it with the original TLT-5P forward lean... shimmed my toe piece significantly to compensate. Curious for those who have made their own shims: do you just use it as a spacer, or mount the shim to ski and binding to shim? I shimmed my speed radical toe piece to try and replicate the ramp of the Sportiva RT bindings I started with on my Hi-5s, which had about 4mm difference between toe and heel pins (light and adjustable bindings... until they break; and they all break). I was concerned that the loads on the long screws would be too large with this thickness shim, opting instead to mount the shim to the ski with a different hole pattern, then mounting the binding into the shim. This also requires the use of UHMW plastic, as I don't think LDPE is robust enough to be mounted to directly. So while they're damn secure, it does add a touch of extra weight. Are lots of people successfully using thick-ish shims with long screws? I figured an extra two ounces of hardware was reasonable to guarantee the binding won't rip out in a no-fall zone, but perhaps I'm just over-engineering in paranoid fashion...

[Spyderjon]

Really didn't like it with the original TLT-5P forward lean... shimmed my toe piece significantly to compensate. Curious for those who have made their own shims: do you just use it as a spacer, or mount the shim to ski and binding to shim? I shimmed my speed radical toe piece to try and replicate the ramp of the Sportiva RT bindings I started with on my Hi-5s, which had about 4mm difference between toe and heel pins (light and adjustable bindings... until they break; and they all break). I was concerned that the loads on the long screws would be too large with this thickness shim, opting instead to mount the shim to the ski with a different hole pattern, then mounting the binding into the shim. This also requires the use of UHMW plastic, as I don't think LDPE is robust enough to be mounted to directly. So while they're damn secure, it does add a touch of extra weight. Are lots of people successfully using thick-ish shims with long screws? I figured an extra two ounces of hardware was reasonable to guarantee the binding won't rip out in a no-fall zone, but perhaps I'm just over-engineering in paranoid fashion...

Shim is usually just a spacer with longer screws running through clearance holes in the shim. B&D do a 6.25mm shim set with suitably longer screws which can also be ordered separately. For thicker shims/longer screws the easiest thing to do is use BF/QK inserts using the M5 machine screws which are readily available in any length.

[Jonathan S.]

[...] Sportiva RT bindings [...] (light and adjustable bindings... until they break; and they all break).

The toe pincers, or some other part?
(Kind of a moot point since Sportiva has stopped rebranding the ATK RT ... although if the reason was breakage, then I'm really confused as to why Sportiva continues to rebrand almost exactly the same toe in the form of the RSR?)

I was concerned that the loads on the long screws would be too large with this thickness shim, opting instead to mount the shim to the ski with a different hole pattern, then mounting the binding into the shim. This also requires the use of UHMW plastic, as I don't think LDPE is robust enough to be mounted to directly. So while they're damn secure, it does add a touch of extra weight. Are lots of people successfully using thick-ish shims with long screws? I figured an extra two ounces of hardware was reasonable to guarantee the binding won't rip out in a no-fall zone, but perhaps I'm just over-engineering in paranoid fashion...

On which Dynafit model are you trying to replicated the RT 2mm delta?
With the Speed at 13mm and the Vertical ST/FT at 17mm, that is indeed a mighty thick shim!
(More numbers at the 4th & 5th tabs of the spreadsheet linked from the beginning of the fourth paragraph here: http://avycourse.blogspot.com/2010/0...uirements.html)
The thickest I've ever used is 6.35mm (i.e., 1/4" LDPE from SmallParts.com).
I have seen even longer screws used for OEM alpine downhill binding shim direct mounts, but I've wondering about those too.
And I agree that LDPE seems like a poor choice for two-part mounting.

[andybrnr]

Jonathan,

Toe pin failure. The two pairs I had both failed this way, and I believe Silas's RTs failed this way, as well. Not sure about the manufacturing process, but it looked like some form of stamping was used to create the flange on the back of the pins that "secures" (hah) them in the toe piece wings. In both of my cases, the flange deformed or cracked over time, allowing the pin to begin wiggling and further fatigue/deform the flange. After the second pair, I got my money back and remounted with Dynafit speed radicals. Bought a chunk of 3/8" (9.5mm) thick black Delrin from TAP plastics, jigsawed out two rounded rectangles a bit larger than the speed radical toe, and then did the two part mount. Delrin has excellent dimensional stability vs temp and generally good mechanical properties; so far I've had no problems. Added weight is about 2oz per ski.

I'm curious if there is a similar history of failures with the ATK toe pieces in the Euro market... tried to research it but didn't find anything, perhaps if I googled in French or German I'd have better luck. The weird thing is that the toe wings themselves seemed fine... merely the mechanical retention of the steel toe pin within the Al part. This seems like a very fixable manufacturing bug, but no such luck. Either they had a bad batch of steel that made it into a lot of the parts that were imported to the US, or they failed the materials science game.

[Jonathan S.]

Yes, that is my recollection of how Sir Si's RT failed. And now I realize that you told me about your RT failure in the Hyak parking lot! (Hard to keep straight TGR user names, email addresses, and actual real world people...)

Interesting that ATK is kind of upping the ante on the RT with the new Raider 12 version this season:
http://www.atkrace.it/raider-12.html

Delrin seems like it would be a good material, based on its use in the Plum heel units.
I vaguely recall that custom two-part mount setups were popular among tele skiers back when their direct-mounted bindings were always ripping out of skis. I can't remember what kind of plastic they used, although then again, following their lead on something like that probably wouldn't be all that wise in general...

[johngfc]

Yes, that is my recollection of how Sir Si's RT failed. And now I realize that you told me about your RT failure in the Hyak parking lot! (Hard to keep straight TGR user names, email addresses, and actual real world people...)

Interesting that ATK is kind of upping the ante on the RT with the new Raider 12 version this season:
http://www.atkrace.it/raider-12.html

Delrin seems like it would be a good material, based on its use in the Plum heel units.
I vaguely recall that custom two-part mount setups were popular among tele skiers back when their direct-mounted bindings were always ripping out of skis. I can't remember what kind of plastic they used, although then again, following their lead on something like that probably wouldn't be all that wise in general...

(... with apologies for thread poaching ...) I'll be on my second year with ATK and wondered if you have any advice for preventing or avoiding the toe pin failure. I'd also sure appreciate any advice for how to attach safety straps to the ATK/LaSportiva bindings. FWIW, I'm 150 lbs and using these with Movement Bond-Xs, which I think is a fantastic lightweight (< 6 lbs) setup for routine backcountry and hut trips. I'm using them with TLT5's and will not use them for anything heavy-duty.

The safety strap issue is really a big deal. I'm afraid of putting something through the hole in the end of the lever (too much torque on the thin lever), but I really don't see anywhere else to attach a cable. I looked one farther back, but it can slip off. These can be tricky to get on and I already had one ski take and unaccompanied trip down a glacier - luckily it caught air off a bump and speared into the snow only a few hundred feet down.

[GeezerSteve]

I'm afraid of putting something through the hole in the end of the lever (too much torque on the thin lever), but I really don't see anywhere else to attach a cable.

I have the same concern so I use these, screwed into the ski one inch or so in front of the toe fixture.

[andybrnr]

Cross your fingers? I dunno, I did ski the resort a fair bit with them, but no big drops and I think I only ejected twice over the lifespan of the bindings. Silas is not particularly rough on his gear, and if they let go for him, I think they'd let go on anybody... again, I wouldn't be hugely surprised if this turned out to be a bad batch of toe pins that made it into the supply chain, but the lack of official communication is unfortunate. I remember a Wildsnow thread where Colin Lantz, the manager for Sportiva's ski line, said returns had not been above normal in response to someone else's complaint of toe pin failure, but they pulled the RTs out of their product offerings for some reason...

[johngfc]

Thanks - I'll try the D-ring. I considered this, but worried that it wouldn't be strong enough in the event of a fall and would pull out. On second thought, maybe that takes care of the need for a safety link. I have ATKs that I got from Telemark Pyrenees (i.e. European version) so if it's a bad batch issue maybe I've dodged the bullet.

[GeezerSteve]

Note that I use B&D coil leashes so if I lose a ski the energy is dissipated a bunch before the D-ring screw is loaded.

I seem to recall seeing Silas's bad ATK toe. Was it a jiggly toe pincer, not a broken wing?

[SlippBC]

Angle Threw me off. I used shims and problem solved. Alternatively sollyfit/ dynalook toe piece is burley works very well.

[andybrnr]

Note that I use B&D coil leashes so if I lose a ski the energy is dissipated a bunch before the D-ring screw is loaded.

I seem to recall seeing Silas's bad ATK toe. Was it a jiggly toe pincer, not a broken wing?

Yah, jiggly toe pincer, which is the only failure mode I've seen on all the broken ones.

[Jethro]

A few years ago, after switching from Fritchis to Dynafits, I welcomed the ramp angle compared to the heel -low feeling of the Fritchi. I have no problem going from a Look binding to my Dynafits. I have had FT12's and Radical FTs, which I believe have some of the higher ramp angles.

[Driver]

For people who have always shimmed, do you believe mounting at the higher stack height with longer screws has caused increased stress in the toe piece that could or has manifested itself as slop or breakage? There is recent discussion of this in a Wildsnow thread about the B&D shims (Andybrnr I believe you may have posted your concerns there as well). One guy comments that his toe piece ended up basically spinning, which he believed was the result of additional leverage caused by the shim.

http://www.wildsnow.com/11304/instal...speed-radical/

http://www.bndskigear.com/dynafitcustom.html

[coldfeet]

Longer screws mounted through a shim put more leverage on the screw-ski interface and there is an extra place for a little slop. Then once a screw gets a bit loose, the interface will go to pieces quickly.

AFAIK, the Superloop telemark binding with long screws that went through a 10mm riser had problems and pull-outs once people started using big plastic boots on it (this is before my time but I can see how it would happen). The cure is to use a double mount, binding to riser, riser to ski.

People on telemarktips used cutting board material for that, which is usually LDPE, and would probably work fine. If you were worried about failure of the screw threads in the LDPE, you could always T-nut it and use machine screws. This is a bit harder to do with a thin shim. For that you might use HDPE or UHMW from a plastics shop.

[Driver]

Interesting thanks. Maybe an old riser plate from some slalom skis would work with some cutting. Not sure what material those are made of- I have some old RC4s with some kind of hard plastic riser. Would be cool to design a riser like that which slots the toe piece in neatly.

All of this sort of begs the question: why doesn't dynafit engineer something to flatten the ramp? I guess the brake requires the heel to be higher up, and they can't compensate in the toe piece without structurally compromising it.

[gregL]

All of this sort of begs the question: why doesn't dynafit engineer something to flatten the ramp?

I keep asking for 11mm and 14mm thicker toe baseplates, which they COULD just throw in the box for those that care. So far no response from Dynafit, but you never know. Playing around with a Beast 16 in the kitchen at the moment, and the ramp measures out to about 5.9mm (kind of hard to estimate where the center of the elliptical pins is, I am measuring to the Torx screw that holds the climbing riser on).

[GeezerSteve]

Longer screws mounted through a shim put more leverage on the screw-ski interface and there is an extra place for a little slop. Then once a screw gets a bit loose, the interface will go to pieces quickly.

AFAIK, the Superloop telemark binding with long screws that went through a 10mm riser had problems and pull-outs once people started using big plastic boots on it (this is before my time but I can see how it would happen). The cure is to use a double mount, binding to riser, riser to ski.

Have you actually experienced the interface "go to pieces" with shimmed tech toes? The forces on tele bindings screws are very different -- way way way higher pullout forces, especially on the rear screws, e.g., BD O1 pullouts. Plastic tele boots = crowbar cycling w/ each tele turn. Dynafit in tour mode = low friction pivot = virtually no pullout force; Dynafit in ski mode = virtually no levering. To be safe I helicoil my shimmed tech toes, no problems. ETA: I and others have opined on another thread that tech binding pullouts usually result from loose binding screws.

[Spyderjon]

......Playing around with a Beast 16 in the kitchen at the moment, and the ramp measures out to about 5.9mm (kind of hard to estimate where the center of the elliptical pins is, I am measuring to the Torx screw that holds the climbing riser on).

Dynafit tech manual says 6mm delta on the Beasts when using their One/Mercury/Vulcan boots which is what mine measure out at.

[coldfeet]

Have you actually experienced the interface "go to pieces" with shimmed tech toes?

Definitely not (I haven't shimmed a tech toe) and I agree with the rest of what you said about the forces being generally different/worse on tele bindings. I would expect the worst forces on Dynafit toe screws to be from kick turns and the like. Maybe knee falls in tour mode also.

The forces on tele bindings screws are very different -- way way way higher pullout forces, especially on the rear screws, e.g., BD O1 pullouts. Plastic tele boots = crowbar cycling w/ each tele turn. Dynafit in tour mode = low friction pivot = virtually no pullout force; Dynafit in ski mode = virtually no levering. To be safe I helicoil my shimmed tech toes, no problems. ETA: I and others have opined on another thread that tech binding pullouts usually result from loose binding screws.

Yeah, my point is just that there was some prior cases where if there was going to be a problem, it would be worse with through mounted shims. I also suspect that pull outs are most likely from screws that get a little loose, presumably chewing up the threads. (including the telemark case)

[gregL]

Dynafit tech manual says 6mm delta on the Beasts when using their One/Mercury/Vulcan boots which is what mine measure out at.

Yeah, guess I should round up . . .

[Driver]

To be safe I helicoil my shimmed tech toes, no problems. ETA: I and others have opined on another thread that tech binding pullouts usually result from loose binding screws.

Steve- interesting. have heard of people doing inserts for swap ability. But you are saying the inserts will resist the additional leverage created by a longer screw and thus limit potential for loosening?

[PNWbrit]

Steve- interesting. have heard of people doing inserts for swap ability. But you are saying the inserts will resist the additional leverage created by a longer screw and thus limit potential for loosening?

He said helicoil not inserts.

[Driver]

Helicoil inserts no? http://www.helicoil.com.sg

In any case, this is the response I received from Dynafit. Emailed and asked why the ramp angle and what the office line is on shims. Props for the super fast and clear response:


"We design our bindings in an attempt to appease the widest number of consumers. Many consumers (especially in Europe) like to ski in more of a forward position. Personally I would rather be more up right so thankfully there is the shimming option.

Using the shims should not negatively effect the integrity of the binding and I do it in my personal set up."

[GeezerSteve]

Common mag usage: "insert" = Binding Freedom, etc.; "helicoil" = Helicoil ski inserts

I helicoil my touring skis for several reasons. Per my crude wholly unscientific pullout tests, screw/helicoil interface (bigger cross section) is way stronger than screw/ski core interface. But the latter holds up fine for 99+% of mounts so it's more about peace of mind. I also helicoil touring mounts to know I'll have a good interface if I need remove and replace a binding in the field.