Leveling out binding height

[MattP]

@DefectiveDave‌ on one side of the HDPE I did a 6/16 and on the other I did 5/16.

 

@davemac‌ There are cuts on both sides that allow the plate to flex. The square holes just remove weight and allow more flex.

[DefectiveDave]

@MattP,

 

Routing turned out to be more of a pain than expected so I'm going to try it out as is until I can think of a better way to deepen the channels. I ended up about 3/16" above level (as opposed to the 3/8" below where I started) once I added the foam pad underneath the HDPE, so I'll need to do some planing later.

 

It didn't seem too heavy just holding it, but now that it's attached to the ski it feels massive. I doubt I'll notice it on the water, but I can see why you put so much effort into trimming the fat. Right now it looks very similar to your version 1.

 

 

[thager]

Just a thought here, but the HDPE does come in solid black.

[DefectiveDave]

@thager,

 

I kind of like the white myself. Also I had trouble finding the black stuff in small enough sheets at the right thicknesses to be cost effective. I think tap plastics was the only supplier which fit my criterion and I didn't want to worry about the lead time of their cut to size process. From what I could tell that was the only way they sold it.

[davemac]

@DefectiveDave‌... I have almost the exact same binding set up to you and have been watching this topic closely. Just wondering if you gave any consideration to mounting a shorter piece of 3/8" thick HDPE on top of the aluminum plate...then covering the top of it w/ the 3m grit paper? Obviously would require that you obtain 6 longer screws for the rear toe bars since they would have to go through the HDPE.

Anyway, this is my current experimental plan (ordered a piece of black HDPE earlier today). The theory being that it will (hopefully) allow the plate to still flex...since the roughly 11" long piece of HDPE (instead of 14") will be screwed in from the underside of the plate only in the front section, and everything rear of the toe bars will "float". Not sure yet whether I will striate the HDPE w/ those flex cuts (like you and Matt have done)...but will post pix in a week or so after messing around w/ it.

[Wish]

FYI Sam's Club camercial kitchen isles will have rather large sheets of the white. Can get a couple plates out of just one and it's cheap. Know one will know you used a food grade cutting board...

[SkiJay]

@MattP @DefectiveDave‌

When a ski flexes, the top sheet compresses more than the base stretches. The back plate deals with more ski flex than the front plate, and the higher the back plate is elevated above the ski's top sheet, the more compressive force it gets when the ski flexes.

 

It looks like you have the riser/spacer flex nicely sorted, but the plate itself is still rigidly resisting tail flex, only now with more leverage. I'm curious to know if any of these setups have had issues with mounting screws loosening up regularly or even failing. If the back of the plate could be semi-floating, like the back of a Sequence plate, it may restore even more tail flex and take some strain off of the mounting screws.

[davemac]

I was also concerned about the lack of flex in the HDPE. Another idea floating in my head is to use a piece or pieces of rubber that are pliable, but not compressible. Attached is a pic of an RTP I use from parts I had for the Sequence plate kit.

The pebble pad (that sits on top of the plate) was a bit slippery for my tastes, so I flipped it over and put grip tape on it.

My goal is to have both feet on the same plane. I'm using a front reflex with an insole in it, and thus I need to build this current rtp up 3/8". Most rubber I have found is compressible. One item that might work is some rubber workspace floor tiles (18" x18") I found at home depot. They are 3/16" thick, so would use two of them in the same manner as in the rtp photo to creat a new "footbed" to put on top of the aluminum plate and also support the black plastic toe bar on either side, and would not restrict the rear plate from flexing.

homedepot.com/p/Multy-Home-Utility-Charcoal-18-in-x-18-in-Vinyl-Flooring-6-pack-MT1002294/203071085

Hopefully this makes sense? I was going to make reference the show "MacGyver", but not sure Matt is old enough to get the joke.

[MattP]

@davemac my first try was with HD floor foam tile. It compressed over time.

[davemac]

Damn....was it the vinyl one I linked to above ?? It didn't seem like it would compress as it is designed to have washing machines on top of it. There was another option there that didn't seem as durable. This... homedepot.com/p/Multy-Home-Black-16-5-in-x-16-5-in-Activity-Floor-6-Pack-MT1002497/203433570

 

The other variable is whether it (spacer material) is installed above or below the aluminum plate. My thought is if it is riding on top of the plate...it will be less likely to compress...or at least compress more slowly...and also allow the aluminum plate to do its job (flexing)...

[MattP]

@Davemac actually that flooring look different than what I had. Hmm interesting good luck with your project. Let us know how it goes. How will you get it to 11" instead if the standard 14"?

 

@SkiJay‌ I have not had any issue with screws loosening/ failing. I do check all my screws before my sets though.

Hmm interesting to think about allowing the plate to "float". How might one accomplish this?

 

@thager‌ it does come in black but I got a good deal on my white.

 

@DefectiveDave‌ Just use the table saw to make the slots deeper.

[davemac]

@MattP‌ not sure I understand your question. The vinyl flooring tile I'm looking at presumably will cut w/ a razor knife. Since I'm planning on putting it on top of the plate, it doesn't need to be 14" long (the full length of the plate). I'm a size 8.5 shoe. I'm thinking about making a "pad" roughly the same length as the one posted in my picture....with a layer of grip tape on top.

Bummer is the 18"x18"tiles are only sold in packages of 6 for $30....and I only need one. If it works, I'll certainly send you one. Seems HD only stocks them in their larger stores.

[MattP]

@davemac‌ ah I understand now. I was thinking you were going under the plate with it. Well I can ship you some of mine if need be. I live 3 miles from the busiest HD store in the world and 3.5 miles from the cooperate office... It has everything.. Buy some and using it for flooring in front of a work bench or something

[DefectiveDave]

I skied on the elevated RTP today and it really seemed to make the ski come alive. I ran 3 33mph in a row (every time I tried) when generally I only run it ~30% of the time. One of them was really nasty and I had to recover from a totally botched 2 ball. I had no problems recovering and I felt the ski was very fast. Overall I'm feeling this experiment is successful so far, but I'll hold off final judgement for now. I did have issues with my toes butting up against the reflex release mechanism, but I got used to it as I kept skiing.

 

 

@davemac,

I did give consideration to the 3/8" HDPE, but eventually decided on 1/2". At the time my measurements seemed to be indicating the rise was 7/16" and I wanted to mount it a bit high rather than low (now I know with certainty it is very near 3/8"). I also wasn't sure what the total height was going to be once I mounted in on the foam rubber pad and I wanted enough slop that I could plane it later. I didn't think about mounting it above the top plate, but it could be a good idea. Mounting to the top would definitely reduce the amount of material you need and hence reduce the weight. I would worry a little bit about bending the screws if they are only mounted to the front of the plate. Longer screws will experience greater moment which will increase the risk of bending them in a fall. There's also some risk (and I haven't done any analysis) that the bending of the ski could bend the screws and fatigue them over time.

 

Also, with respect to your post about using rubber. I originally looked at foam rubber and regular rubber before settling on the HDPE. Regular rubber in general can be more flexible but is significantly heavier than HDPE (which floats while most rubber does not). Most foam rubbers are soft and will compress immediately or over time per @MattP's experience, but I'm sure there's something out there that could work. I wonder what material Radar uses on their ARTP? @Waternut's has held up very well over time and that foam rubber seems very light. I might even be able to mount a flip flop to the plate if I find the right epoxy, hmmmmmm. Keep us informed about your floor tile experiments, they seem like they have a lot of promise!

 

@SkiJay‌,

I think you're right in that the additional height significantly increases the second moment of area for the rear of the ski. The slots help somewhat, and I know @MattP's version is more flexible, but mine only requires about 30lbs to bend 1" and is 14" long. Any idea what the stiffness of the average ski is near the tail? I will definitely be working on reducing the stiffness going forward. I'm also a bit worried about the screws fatiguing over time, but today they seemed to have held up well. I took it apart to be sure.

 

I actually don't have a sequence plate and I'm not sure how it floats, but it might be a good idea to supplement @davemac 's idea of leaving the back completely free floating. I'm assuming we would use a spring loaded washer of sorts to allow motion up and down while holding it in place? This would definitely decrease the contributing stiffness of the riser, but could fatigue the front attachment. The screws required are just long and thin so I worry about them.

 

@MattP,

I wish I could use the table saw again, but my friend is out of town on vacation. I'll probably be using his planer too when he gets back. *shakes head* I really should get some of my own tools, but skiing takes up all of my toy budget and paying for tool time with beer is so much fun.

 

@davemac, @SkiJay,

After responding to you guys, I'm sure it would be more ideal to mount on top of the plate with something more flexible like foam rubber. Lighter, less stiffness contribution, and more comfy. We just need to find the right material and configuration! I'll start my own independent research in this direction too. In the meantime I'll keep playing with the HDPE prototype because it seems to be working well for me.

[MattP]

@DefectiveDave‌ sounds like you have a good grasp on everything. Keep us in the loop! Yeah I have 2 table saws and a planer among countless other tools in the garage. Perks of living with the owner of a construction company and one of his employees..

 

@SkiJay‌ got my gear out of the car and checked my screws. My rear RTP screws were loose.

[davemac]

I bought a pack of that vinyl flooring this afternoon and just cut a 14" piece in the shape of the aluminum plate. I'll work on it this week, but I think it has promise. You can score it w/ a razor knife then "break" it off. It is not too heavy, very pliable, and wants to lay flat. I also like the fact that it can be drilled...which will be helpful for the 3 screws for each of the toe bars.

 

 

@DefectiveDave‌ ...funny you mention the Radar ARTP (or what some refer to as the "sandal"). It has that very thick ergonomic footbed. In measuring that, it only falls 1/8" thinner than my front Reflex...which could be easily remedied with a plastic shim.

My issue is that I really don't like those bungeed tongue/overlays on the "adjustables" since they flex too much.

My backup plan to all of this is to canabalize that binding (with the help of a razor and dremel) and install a conventional overlay on it ...but I digress.

[Deke]

Just a thought about the compression that @skijay mentioned...

 

Couldn't you make the spacer two blocks, one toward the rear and one toward the front? As long as they don't touch each other they won't contribute to compression problem. Could also save a lot of weight too.

[Waternut]

@davemac My radar artp has strings not bungee. It doesn't budge once set.

[davemac]

@waternut Agreed, and I guess I should clarify. By bungee, I was trying to refer to how the tongue section of the overlay is attached with a stretchy material that allows the tongue to "float" around some. Maybe because my foot is at the smaller end of the "one size fits all"... I just like the more positive feel of a solid, traditional overlay, and don't care for how the ARTP tongue initially stretches forward when kicking in...and seems inconsistent in where it recoils to.

[Waternut]

Gotcha... Everyone has their own feel. Just wanted to make sure you didn't have an incorrect opinion.

[davemac]

 

So I ended up using the 3/16" thick vinyl tiles from HD (they do have large dimples on one side, but don't think that will matter). I initially cut several of them out to match the aluminum base plate (first pic)...which was pretty simple to do w/ a razor knife...tracing around the plate.

Aside from elevating my foot another 3/8", two goals were to minimize weight, and not compromise the plates ability to flex...so I elected to stack two of them on top of the plate, and trim them shorter -to be not much larger than I need. Also drilled (6) holes for the toe bar (second pic).

I covered the top layer with 3M grip tape. Final product is in last picture. (Yes, I realize I don't have a big toenail...but I couldn't afford a foot model, and don't know how to photo shop).

Obviously I needed (6) longer machine screws for the toe bar. Turns out the #8-32 x1-1/4" ones I picked up were a bit too long (and 1" is not long enough)...so I just ordered a pkg of 1-1/8" length on ebay...which I'm now waiting for....for final assembly and test.

Hopefully this info is helpful to someone... or at least interesting.

 

One downside of this was that I had to purchase a 6 pack of the 18"x18" tiles ....so I have extras. Three "spacers" can be cut out of each tile. If anyone wants some, drop me a PM.

[DefectiveDave]

@davemac,

 

Nice work! A few of quick questions, how much does the entire layup weight (my HDPE layup weights about 480g), how compressible does it feel, and how flexible is it? Thanks for keeping us posted.

[davemac]

Well it is hardly compressible at all, but it is very flexible.

I have no means to accurately weigh it here at home (I struggle not to obsess over component weights on my road bike, thus haven't purchased one of those small scales). I can have it weighed in the mail room at work tomorrow. Do you want me to just weigh just the two trimmed tiles...or full 14" length?

 

I should add... if someone is looking for just another 3/16" elevation, I would think one of these could just as easily be placed underneath the plate...with having a neglible effect on flex

[SkiJay]

@MattP‌ @DefectiveDave‌

 

The picture below is of the back of my Sequence plate. The wear marks show how the plate is able to slide back and forth between the ski's top and the bottom of the plate that "secures" the Sequence to the ski (the plate that the screws are counter sunk into). These wear marks only became visible when I had moved the plate forward a hole. The actual travel due to flex is probably no more than 1/32". But I think the higher off the ski your RTP plate is, the more movement there will be (or shear force on the screws there will be if no "floating" movement is allowed).

 

If you clamp the back of the binding plate down with washers, I think it's pretty secure sending all of the force into flexing the screws. But by using this mounting plate across the whole back end of the Sequence plate, I think it spreads the load of the mounting screws out over a wider area, allowing the back of the Sequence to slide back and forth rather than bind. As a side note, this wear was without using the floating spacers that are designed to be part of the Sequence system. I sometimes put oil between the fastening plate and the Sequence plate to let it float easier. And you might need to elongate the holes in the back of your RTP's plate a little to allow this float.

 

[DefectiveDave]

@davemac,

 

I think just the 2 trimmed tiles would be great. Those represent the total weight added by your mod correct (no counting the grip tape and lengthened screws which is probably negligible)? I think with your approach mounting them on top of the plate is definitely the way to go.

 

@SkiJay,

 

I see what you were saying now about the sequence plate float. Rather than simply being impinged when the ski bends, there is extra room around the bolt in the direction of bend for the plate to "slide" along the surface of the sequence plate mounts. I think you are right, it would be pretty simple to elongate the holes of the RTP in the direction of bend to prevent the impingement and subsequent increase in stiffness. As you said, washers could then hold the RTP in place (but not too tight). This could easily be applied to the HDPE concepts and would be very helpful to decrease the stiffness contribution.

 

Here's a related question, are skis designed to take into account the stiffness added by specific binder systems? For example maybe an HO ski is designed for the Apex or Exo systems while a Radar might be designed to account for the stiffness of a Vapor boot system?

 

Maybe we should be trying to match the stiffness of a specific binder system when we level the binding height? I'm curious if it makes a big difference. I'm currently sking on an A3 which seems to have mounting holes for both Apex and Exo binder systems. Given the large metal bar of the Exo system, I must assume they both have drastically different bending stiffness and the design probably wasn't "tuned" for both.

[SkiJay]

@DefectiveDave‌ I suspect that the amount of flex difference introduced by plates and bindings that are at least similar is negligible.

[davemac]

@DefectiveDave‌ I could only weigh those tiles in oz (but converted to grams).

A single 3/16" thick tile matching the 14" long aluminum plate is 8.2oz (232g).

A single tile trimmed down and mounted on top of the plate is 6.5oz (184g).

So looks like the two tiles I utilized added about 13oz (368g)

[DefectiveDave]

It's been 6 months since the last comment in this thread, so now seems like a good time to bring it back. I skied on my raised RTP configuration until about 1 month ago with mixed results. I've since gone back to the original configuration with the rear binder flush with better results for reasons I will soon discuss.

 

I originally thought raising the rear binder height to be more level (in practice 3/16" above my front foot rather than 5/16" below) would make it easier for me to shift weight to my front foot in the turn and really bury the ski. In practice this really does appear to work and I found it easier to shift my weight forward into the turn. However, it was by no means an automatic action and I would say it just took slightly less effort. Yet, what I soon began to notice is that it was actually significantly harder to maintain that weight shift throughout the turn. Furthermore, I found that my ski tip tended to be higher while going cross course.

 

My theory here is that raising the rear binder effectively makes the rear leg longer and thus easier/quicker to load than the front foot if one does not consciously work to maintain a good weight distribution. As the ski begins moving out in front of the skier throughout the turn the front foot is loaded while the rear leg bends somewhat due to the path traveled by a front loaded ski and geometric constraint. At this point, any load on the rear foot appears to work to lift the front of the ski out of the water and mess up the carving action. However, at some point due to limited dorsiflexion of the ankle, the rear foot is going to load and this (for me at least) happens sooner and more rapidly with a raised rear binder. It also puts significantly more stress on my rear ankle which has been giving me issues. Also, traveling across course I found it was much more difficult to get balanced over the ski due to the increased effective length of my rear leg.

 

Since uninstalling my rear RTP lift, my skiing improved and become more consistent. Funny enough, my skiing also improved when I installed the rear lift, but I suspect this simply made up for my technical shortcomings at the time. While my conclusions definitely don't universally apply to everyone, they might be useful to others. I now feel that raising the rear foot is advantageous only in the pre-turn where one can consciously shift there weight under nominal rope load. Since slalom is such a dynamic sport with conflicting requirements during different stages, I'm switching to a more neutral stance to hopefully balance out and improve my skiing. The added benefit is that it's also much easier on my rear ankle.

 

Of course, most of the above is theory, but in practice getting ride of the rear heal lift has been incredibly beneficial as of late. Has anyone else learned anything interesting from their experiences?

[david_ski]

Thanks for the idea of using HDPE. I went from a 10 year old pair of Fluid Motions to Reflex with a R-style rear binding. I went to hard shells after a serious ankle injury from an OTF crash in 2004. After recovery my ankles have limited range of motion, and getting my weight forward puts my rear ankle at its flex limit. The hard shells have allowed me to ski pain free.

 

I have been playing with binding position for the last 2 months with the new Reflex bindings. Adding insoles, foam heal inserts front and rear. Nothing seemed to work until I went back and took a close analysis of the old FM's. I had over 3/4" of high density foam in the rear binding at the heal. That amount of foam in a full boot binding was not a problem. Adding that amount of foam into the new R-style binding felt unstable with the foot being almost dislodged from the binding. That is where the HDPE comes in.

 

I decided that adding a wedge between the plate and the binding was the correct way to add heal lift without compromising real foot stability. The heal lift allows me to get weight forward without pain. Today I tried the fix and I am very happy with the results. I now really like my ski and bindings.

 

 

 

 

[tap]

For those wondering how much the riser plate can change your flex numbers...

I use a reflex front with a standard toe hold for the rear. I added a constant thickness riser plate under the rear toe plate only. Everyone has their own theories and reasons, mine was simply to make getting forward on the ski a natural position instead of a forced position. Regardless of why you would decide to try this, I thought I'd provide some insight into the change in flex of the ski. (I pretty much just wanted an excuse to play with my flex tester).

 

The riser plate I am using is 0.345" thick (constant thickness) with no attempt to make it more flexible, i.e. a solid plate. The plate is a Walmart plastic cutting board.

 

 

 

I removed the front binding to make the testing dependent only on the rear binding setup. I flexed the ski at 22" from the tail, I chose this simply because it was as close as I could get to the center of the rear binding. All measurements were taken at the exact same location.

 

With a blank ski the 22" flex number is 100 lbs. even.

With a standard toe plate the flex number is 104 lbs.

With a 0.345" riser under the rear toe plate the flex number is 115 lbs.

 

That's a 10.6% increase in the flex number from toe plate to toe plate with riser. As I said, this is just a base line to provide some insight. The thicker the plate you use the more it will change the flex number. Also, I don't know if making the riser plate more flexible will make the assembly any more flexible because the aluminum plate from the binding is most likley doing most of the work, the riser plate is acting as a core material. But the thicker the riser, the further the aluminum plate is from the neutral axis of the beam. If I find some more free time I may try putting the riser on top of the plate similar to @davemac 's setup to validate the theory. Or cutting some slits in the riser and seeing if that does anything.

 

I have no idea how much flex needs to change before the skier can notice anything. However, I will say that I did have to make a fin adjustment with the riser plate in place. I have no idea if that's attributed to the change in flex or the change in my natural position on the ski. And for what it's worth, the new setup is working well for me.

 

 

 

 

[Greg Lukin]

great idea!! I'll keep this in mind when I order my OB4 soon. Assuming my broken foot will handle the wakes now after my op. Testing the foot out this weekend - if no pain then OB4 time.

 

[gavski]

bump....anyone still trying this out?

[vtmecheng]

I'm actually going to play with my RTP height this year. I'm running the MOB front and got a plate with EVA to go under the RTP. It will be interesting to see how it feels once we are up and running this year.

[aupatking]

@MattP what did you find with your experiment?

[mmosley899]

@aupatking @MattP I have sheets of HDPE that I can cut to any shape or configuration on the CNC router. FYI Grainger sells sheets of black HDPE.

[mmosley899]

@gavski i recommend trying the thick eva foam pad footbed first. But HDPE spacers work too, especially for a more solid connection feel.

[skialex]

@vtmecheng I have cut HDPE spacers for a friend who has a 2cm shorter back foot, they worked great. If by any chance you are using a thin footbed like Wiley’s, try a thicker one like d3’s or HO’s. Easier mod and would definitely won’t affect skis behavior.

[gavski]

Ok, so I tried a little testing the last couple of days.

 

I have a heavily customised & cutdown reflex supershell front Binding mounted on an aluminium plate, and a similarly customized radar rs-1 boot at the rear.

 

Firstly, I removed my custom footbed from my front boot, which is about 5mm thick. The thickness of the supershell base is about 5mm.

 

I then added a 1.5mm thin cutting/ chopping board material under my rear rs-1 boot - not under the plate. The rear pivot plate has a foam backing which raises the plate up higher than the front plate by about 1mm..

 

The boots now looked fairly level..

 

I could tell the difference immediately..my rear leg had so much more influence - too much. I gave it 3 passes as my front foot started to ache without the footbed...

 

Footbed installed, again, I could feel the difference immediately..this time, it felt much more balanced. Less influence from the Rear foot, but I felt more centered over the ski...

 

it is still early season, but I am already skiing much better than expected for this time of the year..

[vtmecheng]

Bringing back an old thread. I only ever added a thin spacer to my RTP, between the binding and aluminum mounting plate but not sure if it was enough to really make a difference. Looking at some of the pro skier binding setups I notice that some, like Will Asher, use a Reflex/HO style front release with a RTP that looks to have no cushion (just plate with non-skid for the RTP). This got me curious how high off of the ski is the foot with a Reflex/HO style release binding? How much difference between front and rear does the non-skid only RTP result in?

[whitem71]

Andy Mapple used to ski with both feet (rubber front, RTP rear) pretty much flat against the ski. Said he could feel the ski more and adjust / react quicker etc. I think he even took all the insole padding out of his front rubber boot. I appreciate that both feet should ideally be level ( to create a balanced stance) but raising them any further above the water surely has to reduce the skiers input to what the ski is doing.

[swbca]

I would be concerned about having screws that are 1" above the top of the ski. With ski flex they could be putting a lot of unusual force on the inserts. I would have a plate on the ski with the spacers above the plate.

This is theoretical, maybe others have experience with this mounting variable.

[BraceMaker]

@swbca perhaps yes. But with a RTP I don't think you're going to leverage the plate off the ski that easily. I would think if you absolutely needed the spacer your best bet would be to use counter sunk screws from below the plastic into an acorn nut on top, then use counter sunk screws in the plate below to attach the unit to the ski.

[S1Pitts]

I used a 3/4 inch spacer under my Strada front boot with longer screws for over 2 seasons with no bolt failures. I used stainless steel machine screws.

[dchristman]

@vtmecheng Nobody answered your question. The sole of a Reflex boot is 1/4" thick. That is roughly the difference depending on the thickness of the plate material of the front and rear plates and any underpad. Don't forget to take your leg length difference into consideration. I recommend not winter mode over-anal-izing this. I did and it set me back 2 months this year.

[vtmecheng]

Thank you @dchristman. I was just curious how much of a difference in height some of the pros ski on with great success. Sounds like a 1/4” or so difference may not be much of a thing.

[vtmecheng]

Has anyone on a MOB actually found that raising the rear up has provided a meaningful benefit? I'm questioning if my current RTP shims, totaling 0.12", are even worth it. My front binding is about 1/4" higher with the shims on my RTP. (Edited heights after measuring)