Forums Splitboard Talk Forum Reverse sidecut/taper
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  • #790424
    Darrick
    96 Posts

    Could someone suggest a link, or explain to me the theory of reverse sidecut/taper? How does it differ from just having a big nose with long contact points? There seems to be a relationship between a shorter running length and reverse sidecut but it is unclear to me how this works. Are the ends of the sidecut still the widest point tip/tail? Thanks for the clarification.

    #790425
    permnation
    303 Posts

    On the left, a furberg with 18m scr into reverse with taper, on the right, a 9ish scr tapered Elan Wave Rider.

    #790426
    Darrick
    96 Posts

    Thanks for the picture @permnation. So the wide points are at the ends of the effective edge correct? I have seen Furburg specs that show two effective edge lengths. Is one the beginning of the taper and one at the end? The reason this is interesting to me is that I have been making my own boards since last winter and for a few years I have been nerding out on board design. I completely understand the merits of the furburg design, I just want to understand the taper aspect so I can try it out on my own boards. Any other info would be greatly appreciated.

    #790436
    permnation
    303 Posts

    Hopefully some others with more knowledge chime-in to answer your questions.

    #790452
    buell
    533 Posts

    Thanks for the picture @permnation. So the wide points are at the ends of the effective edge correct? I have seen Furburg specs that show two effective edge lengths. Is one the beginning of the taper and one at the end? The reason this is interesting to me is that I have been making my own boards since last winter and for a few years I have been nerding out on board design. I completely understand the merits of the furburg design, I just want to understand the taper aspect so I can try it out on my own boards. Any other info would be greatly appreciated.

    Furberg’s use of the terms ‘reverse sidecut’ and ‘taper’ refer to what might be more accurately called an extended transition at the nose and tail. Many current boards have this design element, but not to the extent that Furberg employs it.

    This long transition helps make a board less hooky. It also creates a board with more float in powder (long nose) and a short effective edge for maneuverability, which is probably an important design parameter on a board with an 18m sidecut that is designed primarily to make slarved turns on firm snow.

    The end of the effective edge is generally a relationship between the wide points of the nose and tail and the rocker design. In the full cambered days where the camber ended at the wide points of the nose and the tail, the effective edge also ended at the wide points of the nose and the tail. In today’s designs, every board is a bit different and the effective edge usually ends varying distances before the wide points of the nose and the tail. This creates smoother riding boards. Generally, a more aggressive board will have a longer effective edge and a more playful board will have a shorter effective edge. Furberg, with its 18m sidecut and short effective edge is striving to be both aggressive and playful.

    I have two measures of effective edge that I use to try to get an idea of how loose a board will feel during transitions and how much effective edge I will have when I put the board on edge. The first one is, where are the contact points when the board is on a flat surface. Generally, the shorter this length, the looser the board will feel (depending on torsional and longitudinal flex) during transitions and the less likely a board is to catch an edge. A short contact length when flat does not mean the board will have a short effective edge when riding. That will in part depend on the rocker / camber profile.

    The other test is with the board slightly on edge on a hard flat surface and the camber pressed out (if there is any). Generally, the longer the edge contact, the more locked in the board will feel when you put the board on edge while riding. A board with gentle rocker can still have a long effective edge.

    The G3 I had was ever so slightly rockered the whole way but because the rocker was so slight, it had full edge contact when I put it slightly on edge and is a fairly aggressive board (it is also very stiff).

    On the Jones Solution, the nose and tail rocker is steep enough that the effective edge ends well before the wide point of the nose and a little in front of the wide point of the tail. It is more playful.

    The Amplid Milligram’s effective edge ends quite a bit closer to the nose and tail wide points than on the Jones Solution when the board is put on edge.

    The Furberg has a fairly short effective edge for its overall length. I have the first generation Furberg and the effective edge ends before the wide points of the nose and tail. On firmer snow, the ‘reverse sidecut’ area is beyond the effective edge and does not contact the snow. The softer the snow, the more nose and tail length beyond the end of the effective edge will contact the snow.

    #790454
    permnation
    303 Posts

    @buell Thanks for your reply. Board design-tech is not my strong-suit.

    #790461
    Darrick
    96 Posts

    Thanks @buell for your thorough explanation. I’m not sure if you remember but we rode together at June Mountain a few seasons back with Tex on a powder day. You were riding your Furburg. Where are you stationed this year? I’m headed up to the East Side today.

    #790463
    buell
    533 Posts

    @darrick, absolutely, that was a fun day surfing banks.

    We were near Mono Lake again, until yesterday. Drove home to Oregon last night. It is raining. ; ) Enjoy the snow up there for me.

    I am looking forward to reading other posters thoughts on this topic.

    #790464
    Taylor
    781 Posts

    This is a 172.

    In both images the key pinpoints where the rocker begins to rise from a flat surface.

    In the shovel, there is roughly 15 cm of edge that is almost straight, nearly neutral sidecut fore of that rise point, before the shovel starts to curve in. The widest point of the shovel is at the “u” in Furberg.

    In the tail the rocker begins to rise from a flat surface in roughly the same place that the tail starts to curve in.

    @sun_rocket

    #790465
    Scooby2
    597 Posts

    Buell & Taylor just did a great job at explaining how rocker plays into to the effect of a sidecut tapering off early as well (on firmer surfaces). I taper off the sidecut a bit in the front of my boards just so that when you are on edge on a firmer surface you have about the the same length of effective edge in front of and behind your feet despite being set back on the entire board. Like a classic winterstick or european swallowtail design.

    Softer flex on the ends of a board or ski can make them grabby and hooky in cut up snow or crossing tracks or on firmer snow, tapering the sidecut away from the snow or reducing surface area on the ends can reduce the grabby effect. The same can be done by stiffening the flex.

    #790466
    Jason4
    442 Posts

    I think “taper” is getting misused a bit in the last couple of posts.

    Taper has traditionally been used to describe the difference in width between the nose and the tail of a snowboard. A common twin tip park board might be somewhere in the neighborhood of 30cm at the widest point at the nose and tail and 25cm wide at the narrowest part of the middle of the board. Since the board is 30cm at the nose and 30cm at the tail there is no taper. A common “pow” board might be something like 31cm wide at the nose and 29cm at the tail with the same 25cm at the waist. This would be a board with 20mm of taper.

    I think the original Burton Fish had ~20mm of taper between the nose and tail, the Option Pintail was ~15mm and the Northshore was ~25mm if I remember correctly. Almost all of the current pow shapes do this. It shifts the center of surface area of the board forward, usually in combination with a long nose, short tail and a set-back stance which shifts the center of stance back. You end up with a board that you can ride with your weight centered on your feet or even biased towards your front foot but still have good float in pow.

    #790467
    buell
    533 Posts

    It is the ‘Furberg’ definition of taper that is being used. It is a bit confusing. I do not see it mentioned on the current site. It looks like he is calling it reverse sidecut now which is better than using a term that already has a definition.

    This is from his first year’s site:
    Taper

    While taper is a big trend on freeride skis, Furberg Snowboards is the first brand to introduce it on snowboards. Taper means that the turning radius ends a distance before the nose and the tail and pass on to a reversed sidecut towards the nose and the tail. On hard packed snow, boards with rocker looses the edge contact where
    the board bends upwards. There rocker boards are extra suitable to combine with taper. Taper makes the transition from turning radius to the nose and the tail very smooth and long. Therefore the board does not cut through the snow in the same way as the pressure is distributed over a larger section of the edge. Taper also makes it easier to turn the board and ride with sliding turns in soft snow. Taper is so great that if we had to choose between rocker and taper, we would have chosen taper.

    I think the original Fish actually had 40mm of taper which was cut back to 30mm of taper the 2nd year (edit: looks like it was the 3rd or 4th year). That is a lot. I called those boards twitch turners. Twitch your back foot and they were going a different direction. Great in the tight trees, not so fun in open powder.

    #790472
    Taylor
    781 Posts

    A quick note on the Furberg, which is now my go-to resort board…

    One thing it does really well, which just baffles me, is rail large radius, high-speed turns–even on steeper, tough-to-stick pitches. It holds highly angulated heel rails, without folding, on a pencil-thin line. For me, that’s typically reserved for longer boards with carving-oriented, or forward-favored geometry. That the relatively short and flimsy Furberg does so is just astonishing, and yet another nod to the virtues of long sidecut radii and even edge pressure.

    @sun_rocket

    #790477
    HansGLudwig
    601 Posts

    Thanks for that clarification @buell.
    Here’s how I understand it. . . And I could be way off.
    The history of the development of snowboard shapes aside, most snowboards today have ‘normal’ side cut. This has become the standard shape and thus the ‘normal’ moniker which refers to the center of the circle where the radius is drawn on the same side of edge the radius cuts.
    Reverse sidecut is another option borrowed form surfboard shapes and refers to the center of the circle on the opposite side of the edge to be cut. Early Wintersticks and Venture’s now discontinued Euphoria from a few years back are good examples of this.

    This design is catch free and really playful (surfy) in soft snow. However, it’s very difficult to ride in firm snow.

    Furberg combines the two shapes like this. . .
    The green line is the edge of that 18 m circle. The red line is the edge of the reverse sidecut circle. The blue is where both circles don’t touch and transition the radii with nominally straight edges.

    This is a rough sketch and I’ve exaggerated the curves but that’s the general idea. It all seems to me to be a really fancy way to describe elongating the widest parts of the tip and tail.

    Buell and @jason4 are spot on with the misuse of “taper.”

    Be sure to bookmark Splitboard.com's Recent Activity page...
    http://splitboard.com/activity-2/

    #790478
    buell
    533 Posts

    Furberg combines the two shapes like this. . .
    The green line is the edge of that 18 m circle. The red line is the edge of the reverse sidecut circle. The blue is where both circles don’t touch and transition the radii with nominally straight edges.

    This is a rough sketch and I’ve exaggerated the curves but that’s the general idea.

    @hansgludwig, I am pretty sure the ‘reverse sidecut’ on the Furberg begins at the widest part of the nose and tail. Otherwise, it is a part of the sidecut curve (although an increasing radius part).

    It all seems to me to be a really fancy way to describe elongating the widest parts of the tip and tail.

    This.

    #790480
    jimw
    1420 Posts

    It is the ‘Furberg’ definition of taper that is being used. It is a bit confusing. I do not see it mentioned on the current site. It looks like he is calling it reverse sidecut now which is better than using a term that already has a definition.

    This is from his first year’s site:
    Taper

    While taper is a big trend on freeride skis, Furberg Snowboards is the first brand to introduce it on snowboards. Taper means that the turning radius ends a distance before the nose and the tail and pass on to a reversed sidecut towards the nose and the tail. On hard packed snow, boards with rocker looses the edge contact where
    the board bends upwards. There rocker boards are extra suitable to combine with taper. Taper makes the transition from turning radius to the nose and the tail very smooth and long. Therefore the board does not cut through the snow in the same way as the pressure is distributed over a larger section of the edge. Taper also makes it easier to turn the board and ride with sliding turns in soft snow. Taper is so great that if we had to choose between rocker and taper, we would have chosen taper.

    I think the original Fish actually had 40mm of taper which was cut back to 30mm of taper the 2nd year. That is a lot. I called those boards twitch turners. Twitch your back foot and they were going a different direction. Great in the tight trees, not so fun in open powder.

    Yeah, that’s confusing. Just use a different term than one that’s already well understood to mean something else FFS!!

    Anyway, about the Fish… never heard of one that had 40mm, but maybe they did. That is a shitload of taper. I had a Fish from one of the first years and it was 30mm. I split it and the very first run I took it on was this chute:

    I think I just about crapped myself up there, that thing was so twitchy. Never really felt comfortable with it and eventually sold it. I guess it worked for Terje though!

    Then I bought a Malolo, with 20mm taper and slightly less setback. Still too directional for me. Still have that board collecting dust if anyone is interested. It did have a cool graphic! 🙂

    #790484
    buell
    533 Posts

    Jim, it is pretty far back in time now. This is the main reference I am finding at the moment. It is from Alpinecarving.com.

    “Burton Fish: For ’05, the 160 cm length had 40mm of taper, which was reduced to 30mm for ’06..”

    That would be a scary chute on the Fish! Glad you’ve moved on to a Spliff! ; )

    #790485
    Taylor
    781 Posts

    I think it’s important to consider taper in proportion to overall board length. 4 cm of taper on a 190 is very different in terms of effect on board performance than 4 cm of taper on a 150.

    I have been riding the ’16 Venture Euphoria inbounds on powder mornings. It has 3.5 cm taper on a 162 or 164 length and virtually no tail, which is a lot of taper and, obviously, a highly directional shape with forward-shifted surface area (a 33.4 cm wide shovel).

    With these sorts of shapes, a lot depends on how you ride it. It rides beautifully weighted forward–very fast, quick to accelerate off of terrain, and super slashy–like how one would ride in the olden days of big-shoveled off-piste snowboards. For pow, it’s a dream–especially in lower angle terrain, like, less than 35 or 40 degrees, where one isn’t having to scrub lots of speed and where that long shovel can get hooky.

    @sun_rocket

    #790499
    Scooby2
    597 Posts

    Taylor, you are making me want to try one on the groomers with the kids.

    ” and yet another nod to the virtues of long sidecut radii and even edge pressure.”

    maybe its not so much spreading the edge pressure even as it is keeping it close to your feet, limiting the flex of the board in a powered up carve by virtue of a larger amount of effective edge between your feet than outside of your feet. Cool. Nice range of stance options on those boards also.

    If pressure=force over area, then a shorter effective edge should dig in deeper/easier to resort snow and hold better right? Stability at speed comes from the nose and tail not contacting much and thus not flapping around or hooking into too tight of a radius, the long radius, and not much edge far away from the feet (as opposed to standing with a tighter stance in the middle of longer and stiffer carving board).

    #790534
    sdmarkus
    407 Posts

    Hot damn, who the fuck said sb.com was dead?! Good to see some lively convo taking place…

    Stay on it Darrick, can’t wait to ride one of your boards

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