School me on axle spacing

[bobdea]

Been playing around with a boiler plate.

been using the widest axle spacing. 

Whats the general consensus on the pros/cons of different spacing?

my previous plate was a home made job, it worked... sort of, this thing rides like my loaded vanguard (bouncy, playful) as compared to the one I built out of a set of hangls and an old prior that rides nice at speed but was sorta scary when trying to stop or at really low speed. 

[bobdea]

Ohh, and FYI, the thing works really well with softboots too! 

[SunSurfer]

Getting an understanding of what the BBP plate and mechanism does is the key. 

From the point of view of the board underneath, all the forces applied to it come through the baseplates of the mechanism and they do not constrain the ability of the board to bend along it's length. 

Depending upon the torsional rigidity of the plate and the interaxle distance the plate increases the torsional rigidity of the board, and changes the length of the board edge over which that increase is available. Whether that's a desirable thing depends on your point of view and desired performance characteristics. Me, I value torsional rigidity, others value the ability to twist the board edge along the length.

Your own stance distance plays a part. If you make the interaxle distance too short then you will start applying edge pressure fore and aft of the axles. A bouncing on a diving board effect results. Most people don't like this. 

Just as with standard bindings people ride with varying amounts of setback, but now with an extra layer of variability in that the plate can be mounted in a range of positions, as well as the bindings on the plate.

Finally there is actually a choice to make about whether the sliding axle is at the front or rear. When these were in fashion for racers the vast majority, if not all, rode with the slide at the front. Remember that the plate axles allow the whole snowboard to bend, depending upon the snow contour and the forces applied through the baseplates. So from a function point of view the axle position shouldn't make a difference. Many riders using BBP and similar plates complain of a loss of snow feel. Part of that may well be the axle sliding around under the front foot.

So I, and I know I am an outlier here, have my fixed axle at the front and positioned under the line of my metatarsal heads (think between the ball of the foot and the first bone of each toe). The rear binding is set at my normal stance distance and an equal distance from the rear axle as the front binding is from the front axle. The axles are set at the setback of my choice, and I ride centred.

You asked for the consensus. I'm not sure one exists. I've not come across a reasoned explanation anywhere of why one might set up a plate in any particular way. The why is important to me. I recently was provided with a copy of instructions for setting up a JJA plate. It was a series of "do this" but no explanation of why, and some of Jasey's comments made me seriously think he's a legendary rider who doesn' t understand what he's riding. That will seem arrogant to some. In my defence I've been designing, building and riding sliding axle plates for the last 8 years.

So at the end of all this, think about what you want the plate to achieve for you. If you want to "pedal" soften the plate and shorten the axle distance, the opposite if you want super edge hold. What sort of feel do you want underfoot? The fixed axle under the ball of my front foot gives me a very solid feel there.

Experiment, be an observant rider, and make up your own mind.

[bobdea]

Ahh! See this is the type of talk I was looking for. 

Conditions just haven’t been hard enough for me to be totally sure what I should change if I do.

my thought was that if I shortened the distance I’d stiffen the plate BUT also I’d be moving contact points on the board closer together which would maybe make the board feel softer. (Ever narrow up your stance too much and have the nose start bucking like the board is too soft?) 

 

one thing that was for sure, I was turning bigger and it was really hard to learn to trust the board in the soft snow, thing was, not once did I get close to falling. 

[yamifumi]

12 hours ago, SunSurfer said:

So I, and I know I am an outlier here, have my fixed axle at the front and positioned under the line of my metatarsal heads (think between the ball of the foot and the first bone of each toe). The rear binding is set at my normal stance distance and an equal distance from the rear axle as the front binding is from the front axle. The axles are set at the setback of my choice, and I ride centred.

Do you have any picture of this? I am more visual person and would love to see your set up.

Thank you.

[SunSurfer]

Yamifumi, busy over the next day or so but will post explanatory photos when I get time.

[yamifumi]

5 minutes ago, SunSurfer said:

Yamifumi, busy over the next day or so but will post explanatory photos when I get time.

That would be great! Thank you in advance.... I was always curious.... !!

[daveo]

15 hours ago, SunSurfer said:

some of Jasey's comments made me seriously think he's a legendary rider who doesn' t understand what he's riding.

Interesting. After just the first few indepth chats with JJ, I had the complete opposite perception of him regarding his understanding of what he's riding.

[SunSurfer]

@Daveo, thanks for that comment. I have not met him, and can only form an impression from how he has expressed himself in the instructions I read. 

Are you able to explain his thinking behind offsetting the right and left axles in his design of the sliding axle concept? Running through the consequences of this in my own mind I can see no real advantage beyond creating a point of product distinction, and a number of disadvantages.

Edited April 19, 2018 by SunSurfer

[Corey]

My best guess at the logic of the independent pivots based on visualizing what must happen when the board flexes: 

By moving the pivots out of line, the plate and/or board bend with the other, and/or along their length.  This reduces the isolation to some degree.  At it's ultimate with a large difference in positions, the plate will be similar to VIST in that it flexes heavily with the board.  This likely induces more board 'feel', while also stiffening the board flex between the feet.  This probably also induces enormous forces into the board and plate, which makes me nervous.  

What this feels like to the rider, or how the board twists at the micro level, or if either is significant, are beyond my skill set.  The recent pictures of the AllFlex plate bending heavily with the board have changed how I think about plates.  Maybe a flexible plate really is the best of both worlds?  

[SunSurfer]

Corey, the other issue here, recently addressed in another thread, is the difference in between freecarving and racing. 

As I alluded to above, the recent trend in racing isolation plates is for designs that limit the ability of the board to bend, rather than allowing the board to bend freely. The Allflex plate, as you've noted, bends significantly in racing use. But the Allflex is also a design with "axles" at the end, essentially maximising any torsional stiffening that design may provide.

I don't have a handle on how constraining board flex in the midsection is beneficial, but doing it in a way that gives the ability to control the degree of constraint would seem desirable.

I share your concerns about the forces generated by axle offset in the JJA design. The offset would also induce a twist in the board which I think is undesirable. The degree and amount of constraint generated would also seem unpredictable. It's for those reasons I am of the opinion Jasey doesn't understand what he is riding.

[lowrider]

 If  the offset were to position the axles asymmetrically  under ones bindings toe and heel i can see a substantial benefit . I think the desire to eventually limit the board flex is an attempt to trick your mind into thinking you have gained control  of a  variabley  unstable sensation.  Once the board bottoms out your brain has an easier time balancing your body.  At some time during your carve the board will reach it's maximum deflection based on weight g's etc. a full isolation plate will not  illicit the same feel as a plate that has constraints. 

[Corey]

1 hour ago, SunSurfer said:

It's for those reasons I am of the opinion Jasey doesn't understand what he is riding.

Ahh, but do you need to understand the physics/properties/whatever of something to take advantage of it? It's clearly working well for him. 

Plus, in an industry where you can advertise an advantage, perceived or real, you can increase your sales. See skiing. 

[SunSurfer]

As I said, JJA is a legendary rider. But in making attempts to make the most of any piece of equipment, or to solve a particular problem, understanding, or at least an hypothesis, makes the iterations directed rather than random.

Think of F1 car racing. It's not enough just to be a superb driver, the very best can provide useful interaction with the team engineers to tweak the car.

Edited April 19, 2018 by SunSurfer

[Corey]

Understood, but what makes you think JJA's developments are random? 

I'm not a fanboi or something, just curious why you think that he doesn't understand what he's doing. Sometimes letting go of theory is a good way to come up with new solutions. Sometimes it leads to a Hangboard.

[SunSurfer]

At work at present, and don't have immediate access to the plate installation instructions that led me to that point of view. Will post the 2 docs and my comments over the weekend. 

[SunSurfer]

@yamifumi photo below shows the front axle of the only isolation plate I have mounted on a board at present.

The red line bisects each hex head of the axle head and nut. It also shows the line running either side of the parts of the foot that you balance on when you stand ever so slightly on your toes by taking the weight off your heels. It's the dynamic  position we naturally regain balance in. Try balancing while standing only on your heels for a contrast.

You won't recognise the plate design. It's my own design and construction sliding axle isolation (isocline) plate on a Hot Blast slalom board.

Edited April 22, 2018 by SunSurfer

[SunSurfer]

@Corey Attached below are the 2 files from JJA snowboards.

Let me say at the outset that Jasey Jay is a Canadian icon, hero, and amazing athlete, especially given that he's still competing. I'm not here to critique his athleticism or his personality. I'm here to make a critique of the information he has provided, in English, not French, about how to best use the equipment he builds and sells.

When I am teaching and assessing the trainee anesthesiologists I supervise, I know they understand a particular concept or principle when –
they can give me a concise and coherent explanation of the relationship between the body systems and drugs involved
and they can tell me how if I change one, or more, of the variables how this affects the outcome.
It's not enough to say "Intravenous adrenaline (UK)/epinephrine (USA) makes the heart beat faster." to show understanding. It's a correct statement, a fact, but it doesn't tell you WHY.

I was sent these sheets by Kevin Ostlund, an ex national level Canadian snowboard racer, after a heated discussion about what an isolation plate does on the Alpine Snowboard Trader Facebook group. Kevin had just invested in his first isolation plate, a JJA plate. And he'd managed to get some advice from JJA in person about how to tweak it. Kevin was supremely confident he "understood" how his new plate worked.

So to begin with, before I present any critique of it, read the two sheets "Board Setup" and "Interface Guidelines" for yourself. Form your own opinion about how much they help you to understand the "WHY" of how JJA advises the equipment to be setup. Contrast JJA's comments in items 2 through 6 in the Interface Guidelines with my description of what a sliding axle isolation plate does in my initial reply to @bobdea

Board-Setup.pdf

Interface-Guidelines..pdf

[SunSurfer]

Just back from walking the dog in the autumn sunshine here. Great time to think. Realised I need to revise my analysis above of plates & aspects that favour pedalling. Detail follows.

[SunSurfer]

Pedalling on a plate.

Pedalling is deliberately twisting the snowboard edge for performance benefit. Some here are believers, others are not convinced of the benefits.

Either way, with an isolation plate on top a snowboard is more difficult to pedal, compared with just snowboard alone, because the torsional resistance of the plate and snowboard add together. Twisting motion is strongly coupled between plate and board, whereas the aim of a sliding axle isolation plate is to decouple snowboard flex from the plate above it.

Take a childrens 12"/30cm ruler. Hold it at the ends and apply a twisting force along its' length. Now try and achieve the same degree of twist by holding it nearer the middle. It will require much greater force to achieve the same degree of twist when the points where the twist is applied are close together.

The same applies to the snowboard below a plate. If you want to pedal it, choose a flexible/soft plate, but have the axles as far as possible apart as is functional. The soft plate will allow you to pedal the plate. The axles far apart allow you to most efficiently apply that force to the board beneath you. Above I wrote to bring axles closer together. The illustration with the ruler clearly demonstrates that to be incorrect analysis.

However, axles far apart on a soft plate will potentially magnify the "bounce" in the plate. The amount any isolation plate flexes in use depends on rider weight, plate rigidity/flex, but crucially where in relation to the axles the rider applies their weight. The axles act as fulcrums, the plate as a lever, the riders weight as the downforce.
If the riders weight is applied outside the axles, between the board tips and the plate axles, the "diving board" effect occurs. 
If the riders weight is applied well inside the axles, the degree of plate flex for any degree of stiffness will be increased.
If the riders weight is applied over the axles then no matter how stiff or flexible the plate, the degree of plate flex will be minimised. This is because the leverage the rider can exert to flex the plate is minimised because the down force is applied so close to the fulcrums(axles).

The "right" relationship between plate axles and bindings depends upon what performance feature you want to accentuate, over and above allowing the board to flex freely below the plate. That distance relationship will change to achieve a similar effect with plates of different stiffness/flex.

 

Edited April 22, 2018 by SunSurfer
typo correction

[Corey]

Ok, so having a variable resistance to the plate hinge points deviating from the board does what? Ignoring the additional stress in the hinges and boards, I'm not 100% sure of the effect. 

Why ignore extra stresses? Racers need the board and plate to last for one race. I don't think it'll actually wear out that fast, but treat it like F1 tires - you don't care about wearing them out if you win. I don't think wear is that bad, but it's a logical thought experiment to go to an extreme. 

The AllFlex center linkage also limits how far the plate and board can deviate, so they both force the plate to bend with the board.  JJA's would be more progressive, having some effect as soon as anything deflects. 

Either way, I'd like to try both to see for myself.

[SunSurfer]

I have never handled a JJA or an AllFlex plate in the flesh. I'd love to try riding one as much as you would. What follows is a dog-walk thought experiment.

AllFlex type plates are winning races, but what factor in their design is the winning factor? Axles at the end maximising the torsion resistance effects, or is constraint of board flex some or all of the performance gain. But the axles are placed square across the board, they are not offset, and the centre of board constraint levers are set straight across the board, not offset.

The axles act as fulcrums, particularly when constraint occurs, as significant leverage is then generated by the tips of the board. To help visualise what happens to the edge shape when constraint of board flex occurs, because of the offset axles on the JJA design, think of folding a piece of paper in half and watch the edge alignment.

First fold the paper along a line at 90 degrees to the edge you're checking the edge shape of. When folded both edges are perfectly aligned.

New piece of paper, fold along a line where the fold line angles across the paper so that the points where the fold line intersects the edge are 3cm offset. When folded the edges are now substantially offset. That suggests to me that the JJA design will cause unwanted distortion of the board edge, and the effect will be different on toe and heelside relative to the snow.

Perhaps a better way of achieving controllable constraint which is able to be precisely tuned would be to create a design where the travel of the sliding axle is limited in its' slot. On the BBP that could be achieved either by changing the size of the Delrin square bushing to a rectangular section (a very strong design) or by a worm screw adjustable wall for the slot (weaker but more easily tunable).

 

[crote123]

@SunSurfer Not sure if you've seen the whole JJA interface system or not but here's a dumb video I made for someone to show him the components.  Also note that he offers (and suggests) to use another type of brackets for the front (instead of stainless/alu, the're made of UHMWPE and also slide.  It's also thinner). I'd say the front bracket has about a little less than one cm play (I don't have my equipment with me, can't confirm).  BTW, the documents you refer to are about 4 years old. Some things IMHO aren't valid anymore.  I'm not sure JJA even sends it out anymore.  But some suggestions are valid as far I'm concerned (like 2-6).  But item 9 is definitely not valid anymore unless have you an early plate of his.  Furthermore, I know the he also has many designs for his plates (take a quick look at the "Olympic Dreams" video FIS Snowboarding shot with him after his victory this winter, the plate is unlike anything I've seen from him).

 

 

[SunSurfer]

@crote123 Thanks for the updated information. The sliding slot in the interface is the design feature where it's all at. Detailed photos are always appreciated by everyone here who wants to understand how stuff they haven't got their hands on works. If anyone has access to information that JJA puts out currently that will add valuable information to this thread.

Isolation plate development has not stopped. So change will be ongoing and that's good for our sport. The FES development of the AllFlex remains a technical mystery at present.

Edited April 22, 2018 by SunSurfer

[crote123]

@SunSurfer Here's a close-up of the brackets I'm using for my plate.  The ones on the left are the front brackets and you can see the amount of slide they allow.  Also note that there are two pin placements.  My guess is if the pin holes on the outside are used it may allow a little more flex of the plate and having a choice of pin placement may also  help locate the axle in a particular postion under/respect to the binding.  I use the pin setup that's in the picture (no particular reasons, it just works for me there and I'm not sure that I'd see much a difference if I changed it).