Alpine Nordic Telemark (ANT) Binding: Progress Report 1 21 Jan 97 ======================================================= Goals ----- I'm posting a series of progress reports on this newsgroup (rec.skiing. backcountry) to get feedback over the course of evolving several prototype ski bindings with the goal of achieving high performance in the following three modes using a 75mm boot. (If you chose to grind the front of your boot down for use with the Rainey Superloop, your boot will also work.) 1) Alpine: Locked heel downhill. 2) Nordic: Free pivot at the toe as well as bending at the ball of the foot for touring. 3) Telemark: Locked pivot at the toe with bending at the ball of foot for free heel downhill. A ski pole tip is used to change between the above modes. For simplicity, the exit/entry will not be pole-actuated, but will use a standard heel lever with slots for a strap around the boot (similar to the Riva 2). A unique feature of the ANT will be its telemark feel. The amount of return force from the heel to the ski will be adjustable from very weak (as with normal 3-pin bindings) to very strong (stronger than any cable binding). This adjustment will be difficult to change while skiing, and thus it should be chosen to optimize telemark performance with touring freedom coming from the toe pivot. A Brief "Why" ------------- When I proposed such a binding two years ago, there was some feedback on this newsgroup to the effect of "why bother, I'm happy with my current (AT or tele) gear" or "a multi-purpose system ends up being good at nothing." I'll give my response once more. I believe that the telemark turn (with the ball of the foot firmly on the ski) is easier and more fun in certain conditions than the parallel turn. However, the opposite is true in other conditions. A binding that will let you do both is thus desirable. It is also my opinion that a free toe pivot is more efficient for touring than a normal cable binding and that flexing at the ball of the foot is a more comfortable touring motion than having a rigid lower foot in an AT binding. In addition, motion at the ball of the foot improves blood circulation leading to warmer feet. Platform Choice --------------- In order to accomplish these goals as quickly as possible and to have the flexibility of using the same ski for alpine touring when a 75mm boot is not desirable, the first ANT bindings will be a modification of the Ramer Classic platform. For those unfamiliar with this platform, it is a somewhat unique alpine touring binding that pivots at an ergo-dynamic position just under the toe of the boot and releases well (with DIN settings) even when the heels are not locked. The ANT should weigh less than a Classic (1.3 kg), but will probably still be heavier than the lightest alpine touring binding (Dynafit - .74 kg). I hope it will be no more expensive than the Classic (around $225 US). (Weights and prices are from Couloir.) Why not use a Voile platform? ----------------------------- I would have liked to develop a Voile-compatible binding if for no other reason than they currently dominate the release telemark market. The release on my Voile (2 years old) has been functional, and I haven't had any mechanical problems so far. However, there are some problems in designing the ANT to be Voile-compatible. First of all, there is no toe pivot for a touring mode. This is not a problem with most 75mm bindings since they do not have the ability to inhibit forward motion to the degree that the ANT will have. Secondly, there is no dependable release during a hard forward fall in telemark mode. In fact I ripped out two Voile screws (the two front screws of the plastic piece which holds down the back edge of the release plate) during a hard forward fall. I was using Superloops and T2 boots; the ANT could be set to be even more punishing to the Voile, and I'd like to avoid the problem of screws ripping out. On the other hand, the Ramer has a pivot built into the release function so no pivot has to be added. The Ramer can also be easily modified to release during a forward fall in telemark mode. Some Technical Details on the Modification ------------------------------------------ (This section might not be of interest if you are unfamiliar with the Ramer platform.) The Ramer Classic toe piece (the part with 6 screw holes) is used with the ANT and is placed in the normal location on the ski (i.e., the toe piece is roughly centered over mid-chord; if you mount the Ramer Classic using mid-boot marks, you might vary from this point a cm or two). The same Ramer side-arm bars are also used, but the remaining parts are different. To use the ANT, the Classic heel piece (the part with 4 screw holes) must be removed and different hardware screwed into the ski. The ANT requires a 4 mm thick middle piece to be mounted between the Ramer toe and heel pieces. To swap the ANT and the Classic bindings, you will probably want to install screw inserts on your skis for all screws except those of the toe piece. I've been experimenting with some inserts from the hardware store, but haven't found the perfect ones yet. If you already have Ramer Classics mounted on your skis, you should be able to remove the heel piece and install inserts because the inserts are wider than normal screw holes. I've thought about how to integrate ski brakes into the Ramer platform and it seems difficult. I'm working on a possibility that would work for any binding that does not normally take brakes (Dynafit, Silvretta SL, Ramer, etc.), but I haven't gotten very far yet. Please email me if you know if such a product in exists already.) The Ramer Classic has ski crampons available, but I've never tried them. I'm not sure if they will integrate into my design or if I will have to modify them. It should be easy to install ski mounted crampons, but most people prefer the type mounted to the binding. Ok, now the progress part ------------------------- I have experimented with the position of the 75mm boot relative to the Ramer pivot and have settled on a location that is roughly pin holes over pivot. It would have been nice to have this location user-selectable, but I think this would add too much complexity and weight to the design. My first prototype only handled the nordic mode and had an adjustable toe pivot point location. I used an older Rainey side-throw Superloop mounted to a Classic with the normal Classic plate inverted and cut in half. The next prototype to be fabricated soon will be able to test nordic and telemark modes (the alpine mode will come later) and should function fully in these modes (though switching between these two modes will require releasing the binding). For those who aren't interested in a heel lock, this prototype could evolve into an NT binding which would not need a heel piece screwed into the ski and would be lighter than the full ANT implementation. Contact Info ------------ Not everyone will agree with my reasoning, but if some of what I've said interests you, I hope you will consider the ANT binding when it is ready. Don't hesitate to send me any feedback, and if you are in my area and would like to ski a prototype, I'd be more than happy to meet you. If you're interested in the Ramer Classic now, some recent reviews include: Rock and Ice #64 p. 119 and Couloir Vol. IX, No. 2, p. 50. Ramer Equipment can be reached at: 1803 S. Foothills Hwy. / Boulder, CO 80303 USA / Phone: 303-499-4466 / Fax: 303-499-0259. Dara Parsavand (the author) can be reached at: 735 Pine St. / Boulder, CO 80302 USA / Phone: 303-417-1445 #2 / parsavan@prony.colorado.edu ANT Binding Progress Report 2 (Final) 22 Sep 97 ===================================== I prototyped a few versions of the binding I discussed in January (a modification of a Ramer Classic) but have given up on the project due to a lack of interest at Ramer Products and a shift in my own interest away from the 75mm interface (I plan on raising issues related to alternative interfaces in a separate post). For those of you who read my post in January, here is wrap-up. If you have not read this post, the following may not make much sense; I can mail you a copy if you are interested. I came up with some shapes for a one piece bent stainless steel plate that would replace the aluminum U-channel bar (which holds the Ramer side-arms together) as well as form the 75mm wedge to hold a standard 75mm toe (or one slightly cut down). It turned out to be rather expensive to get this piece fabricated, so I ended up modifying an old Rainey Superloop which I could attach to a normal Ramer U-channel that was cut in half. I was able to move the Superloop back and forth relative to the Ramer touring pivot. At first I tried to use slots for this purpose so that I could have a continuous adjustment, but it was not secure enough, so I ended up going with 4 positions (each using 4 holes to hold the back 4 holes of the Superloop plate). This corresponded to the boot pin holes being -2, 5, 12, and 19 mm behind the touring pivot. The outside 2 positions did not seem to tour well - with the boot very far back, it felt like a Silvretta, which to me is very tiring. With the boot all the way forward, the touring pivot was actuated so easily that you could not bend the ball of the foot while touring (one of the points of the prototype was to be able to achieve an NNN-BC like touring motion). The middle two positions seemed reasonable. I removed the cable and guides from the old Superloop and bolted a bail across the top of the toe which is similar to the one used in the current Superloop, except the height could be adjusted (this was suggested by Tom Turiano in a Couloir binding review (IX-2, p.20). To replace the cable, I used an underfoot tension member with a compression spring similar to the Pitbull, except that the cable pivot point was adjustable and the compression spring was underneath the heel. (I needed the area in front of the boot to have enough clearance for touring motion.) The cable pivot points were discrete and not that easy to change. They were located at 25, 42, and 59 mm behind the boot's pin holes. The middle position acted pretty much like a Pitbull, the front position was very similar to the freedom of a 3 Pin binding, and the rear pivot was too far back for my foot size to be useful. Since I had planned to achieve touring freedom by using the Ramer pivot, I wasn't interested in the front position, but I now realize if you could come up with a pole-actuated change in the cable pivot point, you could dispense with the touring pivot and use a different release mechanism (or none if you feel lucky). When I showed the prototype to Paul Ramer, he wasn't the least bit interested. He thought a] the market was too small b] the production costs were too high, and c] the price people are willing to pay would not match this cost. I'm not confident enough in the design I have now to push it further on my own, but if I could have gotten Paul interested, I was hoping he'd have some good ideas and it could evolve into a product that he could manufacture and sell. Since this isn't possible, I'm going to forget the Ramer platform and work on other interfaces. If anyone else is hacking on the Ramer platform and has any questions, I'll try to answer them. - dara Dara Parsavand | 735 Pine Street | Boulder CO 80302 USA parsavan@prony.colorado.edu (use this address if different from header)