How to Shorten the Silvretta Pure Backcountry Skiing Binding
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| Silvretta Pure is an excellent binding for average to smaller size, less aggressive skiers. Thus, it’s frequently looked at for folks with smaller feet. The size small Pure goes down to a fairly tiny boot, and the Pure Kidz model goes small as well. But what if you need a shorter binding and have a longer version of the Pure that’s already in your possession? They’re easy to shorten. Here’s how. |
1. Figure out how much you’ll shorten. Adjust binding length to middle of length range, then place your shorty boot in the binding with the boot toe inserted in the toe wings. Measure the distance from boot heel to binding heel unit, and that’s how much you’ll cut. (When doing this, measure back from the boot heel to the point where the heel touches the binding when being inserted.)
2. Look at the front end of the binding and memorize how recessed the ends of the rails are, so you can replicate later (not critical, just get it close).
3. Carefully drive out the roll pins holding the rails. The roll pins are re-usable if you’re careful. If you mess one up, roll pins are available at hardware stores, but it might be hard to match exact size. Best tool for this would be exact size punch that won’t end up inside the hollow pin. We don’t have that size punch so we began with a small punch on the edge of the pin, and once it started moving we used the butt end of the largest drill bit possible. (Whack the bit with a brass hammer or something equally forgiving, as hitting a drill bit with a hardened steel hammer can be a disaster.)
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| Punching out the roll pin. |
4. Cut the rails. If you happen to have a Pure with aluminum rails, just mark with care and whack them off with a hacksaw. In the case of carbon fiber you’ll need more. Mark with care, then using your hacksaw cut a shallow cut all the way around the rail — before you cut all the way through. Then finish your cut. The idea here is to prevent a “run,” meaning a strand of carbon fiber ends up getting pulled back from the cut as you finish it.
4. Drill the rails — step one. Using the chunks you cut from the rails as a sample, pick a drill bit that’s as close to the hole size as possible, but no larger. In other words, the bit should be easy to push into the existing holes. Insert the rails back in the binding toe unit to the point where they have the proper inset from the front (see step two).
Set the heel and toe down on a flat surface as if mounted on a ski, so the hole locations will be perfectly aligned. Using the existing holes in the toe units as a guide, lightly drill on the rails to mark them. DO ONLY THE TOP FIRST. Remove rails from toe unit, swap drill bits to a smaller (sharp) size, and drill a pilot hole using the mark your larger drill just made. ONLY DRILL HALF WAY. Swap back to your larger bit, and drill out the pilot hole, again only half way through the rail.
If the bit you are using is slightly small compared to the original holes, lightly ream the hole by slightly angling the drill and moving it in a circular motion for a split second. The idea here is to make a hole that you can re-insert the roll pin in under a small amount of compression, but a hole that’s not too big.
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| Marking drill position, remove rails from binding toe unit to finish drilling. |
5. Drill the rails — step two. Now you’ve got a hole on one side of the rails that the roll pin will press-fit in. Insert the rails in the binding toe yet again, and line up the holes you drilled with those in the binding. Insert a roll pin to index the rail position; insert it very lightly so it’s easy to remove in a moment. Flip the binding over, repeat step 4 (remember to remove the rails from the binding while drilling, otherwise you run the risk of accidentally enlarging the holes in the binding), then run your bit all the way through the rail. The idea is you now have a hole that’s perfectly aligned with the existing holes in the binding.
If you do mess up, know that you could easily shorten the bindings a bit more and re-drill the holes. The main thing is to remove the rails when doing any drilling other than marking, so you don’t run the risk of enlarging the roll pin holes in the binding toe unit. Also, note that the holes in the rails and in the binding toe unit must be nearly equal in diameter, otherwise the roll pin will not engage both parts equally and you’ll get wear from movement in that area as the binding is used. Epoxy helps with this issue.
6. Put ‘em back together. Mix up some 1-hour epoxy and smear a small amount inside the sockets where you’ll be inserting the rails. Insert the rails, smear a small amount of epoxy in the roll pin holes, then tap in the roll pins. The idea here is the epoxy makes up for small variations from factory spec. (To reverse, heat up the binding with a heat gun to soften the epoxy.) If the roll pins are shorter than the full distance of the hole, finish by tapping with a punch so they’re inset equally on both ends.
7. Mount using our WildSnow instructions and template, which are not dependent on length of binding.
That’s it, now you’ve got shorty bindings!
Comments
25 Responses to “How to Shorten the Silvretta Pure Backcountry Skiing Binding”
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Hey Lou…
nice tutorial on how to do this job right! Just wanted to mention that another good way to prevent a “run” when cutting carbon fiber is to wrap the place where you want to cut with masking tape (pref. 3M blue) and cut through it like you do when cutting a rope.
Happy Holidays!
Josh
Thanks Josh, good tip!
A similar procedure is rumoured to work with the NAXO bindings as well
Lou – thanks for the how to. I’ll let you know how it goes.
Cheers
Dave
Awesome instructions! Could not find a ski center to mount the pures, and I needed to shorten them also. Came out perfect with a set of ’06 bindings!!!! Thanks so much.
Anyone have any experience with the Silvretta Kidz? They don’t even show them on Garmont’s site. Are they still available? Will they work w/ my daughter’s 234mm soled size 19.5 alpine boots? Anyone know how to create a waxless pattern in the bases of some beater junior alpine skis?
Thx,
=L=
Lou – it worked great. Thanks for the beta
Cheers
Dave
Thanks for checking in Dave, glad it worked!
Lou,
Is it possible to do this mod with Fritschi Bindings?
Thanks.
Gray, it would be complex but could be done.
hey lou, know anyone who would do the shortening…I am a hack with tools.
Roger, I don’t know of anyone offhand.
Works great. Thanks a bunch
I used a 1/8″ Dasco Pro Pin Punch to remove the pins. It fits perfect and removes the pins cleanly.
7/64″ Split Point Titanium drill bit to prep the pin holes and a 1/8″ to finish.
Anyone have a manual for Silvretta X-Mtn bindings that they could scan and email to me?
There were no instructions in the box when I bought them a month or so ago and I need to check DINs etc. since the first time I used them the boots were sliding back in up hill mode and almost popping out of the binding?
Lou, I have been searching for a ski brake to fit an older pair of Silvretta 500 AT bindings. Do you have any available? Can you recomend where to go in the valley? I have been to SC and Gear X, no luck.
Thanks!
Bob
Bob, none here and I don’t know where you’d get them… sorry. Lou
How practical/possible is it to slow down an off-the-shelf pair of waxless cross country skis with kick wax (on the glide portion of the base)?
Lou,
I understand it would be difficult to shorten Fritschi bindings. What would it entail, and how difficult would it be.
Thanks
Gray
Here’s how to do it:
http://tinyurl.com/yetvlva
Good mod. I never got inspired with the Fritschi because as the guy says, the easy shortening method he does can only shorten it a bit due to the slot milled into the tube. Same problem with the front.
I got into shortening the Pures because they work best for lighter/smaller people anyway, so they’re the perfect binding for kids, tiny women, tiny guys, mice, folks like that (grin).
Thanks for the help Lou & others! I just shortened some Pure Kidz to fit my almost-5 year old son’s tiny boots (Mondo 18.5 – BSL 227mm). Easy to deal with, and they look like they’ll work great.
Sweet!
Lou,
I’m in the same boat as Ian Hunt above, I bought a pair for skis second hand with these bindings, and am looking for a procedure to adjust the sole length and DIN settings. Do you have a copy of the manual, or can you provide the nutshell version?
Thanks!
Adam,
Adjust toe jaw height first, with same technique as used with Fritschi or Marker.
Adjusting DIN should be obvious. Lateral release is the front screw on the heel-jaw unit (the “slide” that moves along the dual rails of the frame-plate, and holds your boot heel down). Lateral release indicator is on the underside of the “slide.”
Vertical release is the top screw on the “slide.”
Sole length adjustment is accomplished by rotating the screw at the rear of the binding frame/plate, which moves the heel-jaw unit (the “slide”) along the two rails. Adjust length so your boot heel drops in without jamming, but can still step down and cause the jaw to close on the boot heel.
After doing above, forward pressure (exact adjustment for sole length) is the only tricky part.
According to the manual, “the forward pressure is correct when the forward pressure indicator aligns with the rear wall of the slide.”
Look at the rear wall of the “slide” and you’ll see a small metal collar sleeve that the length adjustment screw passes through. This is the “forward pressure indicator.” Rotate the length adjustment screw till the “forward pressure indicator” is flush with the rear wall of the slide. Recheck that your boot exits and enters the heel unit without binding.
After forward pressure is adjusted, recheck lateral release value by looking at indicator with boot in binding. Adjust if necessary.
Remember that DIN/ISO standard allows a variation of indicated release value of plus or minus 15% !!! That means one full line up or down from what’s indicated on the binding by the numbers. In other words, take care with how high you initially set the release value (true for any binding).
Know that the Pure lateral release is accomplished by the “slide” moving back as the toe of the boot rotates against the fixed and immobile toe jaws. I’ve never been impressed by this system, as the slightest additional friction in the toe area will dramatically increase the lateral release value, as will any slight change in the forward pressure (due to change in adjustment, ice on boot, whatever). Keep your boots clean, and perhaps spray the toe jaw with some silicon once in a while.
Get after it. If you fool around the above should be very obvious.
Lou
RE: An alternative method to shortening the Silvretta, without drilling and sawing.
Hi Lou, hi folks out there,
thanks for your suggestions on how to shorten the Silvretta Pure Kidz. I spent quite some time wondering how to get touring skis for my son.
I was all set up to do it, when my 8-year old asked me what I was going to do. When I had explained the binding, he suggested to use the long screw in the back, which is used for adjusting to boot length, to adjust it to his boot length. I said: “Well, I can’t adjust it to your boot, because the screw is too short.” And he jumped on it saying: “Well then use a longer screw.” Bingo.
What you need to do:
1. dismount the screw which is used for adjusting the boot length. This is an M5x75 mm screw. It’s held in place with an M5 nut. Additionally, there is a washer and a little sleeve that serves as a bearing. Make sure you keep those.
2. Get a longer screw, for example M5x100 mm, same or similar head shape. I recommend to stick with a standard zinc plated screw. Using stainless steel will get you into trouble because of the galvanic corrosion caused on the other parts, especially the sleeve like bearing. Finding this screw is probably the most difficult part. Go to a good hardware store or a large distributor.
3. Install your new screw in the same way as the old one was installed. Use Loctite to fasten the nut to the screw.
4. That’s it. Now you have shifted the length range from the standard 265 -305 mm to the new range of 240 – 280 mm, simply by the 25 mm that you have added to the screw. The nice thing is that you can go back by switching to the original screw.
Pros: no drilling or sawing, no permanent change to the binding
Cons: The binding stays as long as it is, which is quite long for short skis.
The Silvretta binding seems quite loose in lateral direction, and it looks like this will never retain the boot properly. When skiing however, it really doesn’t seem to move much. Works better than you would expect. Still, I understand that Silvretta is out of business…
Thanks again for your great description. First ski tour was a great success. Tiemo loved it. Can’t wait for more powder.
Cheers,
Simon