Ski Builders Forum

Hi All,

I need to build boards this year for my final year mech eng project, I'm doing a study on customised torsional vibrations and stiffness in snowboards.

To do this I'm basically going to build a reference board out of basic materials (base, edges, glass, core, glass, topsheet, epoxy) and then build a few more boards with different properties in the layup (carbon stringers, kevlar and whatnot) and compare them both on the snow and in the lab. The boards will be dimensionally identical, and the core/base etc will remain the same.

I'm new to the whole building process and haven't got a good design of my own nailed, so I was going to very closely copy a board that's already had plenty of testing done - the Rome Anthem. The reason for the choice is simply because Rome has more data on the shape of their boards than other manufacturers. Designing a board from scratch will take too long and is beyond the scope of the project, and the boards I build will never be sold.

I may sell boards on a small scale under my own company name in the future, and the research I do may have direct or indirect benefits, however I will never use their shape. Whatever I use will simply be from the improvements in torsional stiffness and dampening that I find.

I'm not sure on the ethics of doing this though, should I contact Rome and obtain permission? Since it is for university research purposes, there are different laws and ethics applicable, however I'm really not sure if I'm violating any of them.

The properties I'll be using are camber height, sidewall radius, length, stance setback, effective edge, tip and tail height.

Rome is definitely a good source for consistent dimensions.

Keep in mind I believe all their overall lengths are "flat length", or un-bent material length.

Rome i doubt would go after, nor even find out about one person doing one school project using their numbers, they might even be flattered.

To get my 2011 models started off, I honestly pulled them right off their site, then i checked numbers off other companies, did comparisons, and then made changes where I thought we'd benefit, so are my boards a copy of romes? no. But yes their data is an excellent source and a good benchmarking tool.

by the way, we get proforms for rome, and ride lots of different rome boards every year. When not riding a blak sheep board, I was riding a Rome Postermania this season, what an amazing board, as good as mine! hahaha

and Ive mentioned this in other topics I believe, because I had a serious issue with it. But keep in mind the "effective edge" vs "running length" and pay special attention to it in your design.

You will notice on the Rome site that on EVERY board they make, the effective edge is always 5cm longer than their running length.

That allows for a tip/tail bend to start 2.5cm before the end of the effective edge (contact point apex) 2.5cm being "about one inch" I suppose.

This is critical to get correct. at least err on the side of it being bent before the end of the sidecut/beginning of nose curve. Some like putting them in the exact spot or closer than rome would, all I know is if you get it wrong the board ends up super grabby and you will not enjoy the ride.

Keep in mind, if you use snocad to create your board. The "running length" in their program is the end of the sidecut arc, and the beginning of the tip/tail arc. Not only is this point not tangent, but it is also what I would consider not the true running length, and not the true effective edge.

Effective edge, I would consider that being in the simplest terms, the point where the tips are widest. Even if its on the nose curve, concavity being curved back in, way past the end of the sidecut curve.

Running length, is not going to really be determined by snocad, its going to be wherever you design your mold to start curving up. If you have a cambered mold it's going to be that inflection point where the line switches from camber to nose/tail curve, its going to be fudged 1-2cm based on how much camber/rocker you have, how aggressive or mellow your tip/tail radius is, etc.

This is something that probably takes hundreds of test boards to get nailed, but for the purposes of building one board, Bend your tips a little bit BEFORE the end of your effective edge, or the point where your board is widest @ the tips = catch free tips and a nice easy ride. Make them equal, you MIGHT have something with a little more edge hold due to more contact point pressure, get it wrong you have a board that does this push/pull effect while you go down the hill on your edge, and you'll be hating life.

Thanks for the tips Doug, much appreciated. Like I said, my priority is to get a board shape that's rideable so I can do comparisons.

May have to go down to the local board shop and check out an actual Anthem before I start anything that can't be reversed.

knightsofnii wrote:and Ive mentioned this in other topics I believe, because I had a serious issue with it. But keep in mind the "effective edge" vs "running length" and pay special attention to it in your design.

You will notice on the Rome site that on EVERY board they make, the effective edge is always 5cm longer than their running length.

That allows for a tip/tail bend to start 2.5cm before the end of the effective edge (contact point apex) 2.5cm being "about one inch" I suppose.

This is critical to get correct. at least err on the side of it being bent before the end of the sidecut/beginning of nose curve. Some like putting them in the exact spot or closer than rome would, all I know is if you get it wrong the board ends up super grabby and you will not enjoy the ride.

Keep in mind, if you use snocad to create your board. The "running length" in their program is the end of the sidecut arc, and the beginning of the tip/tail arc. Not only is this point not tangent, but it is also what I would consider not the true running length, and not the true effective edge.

Effective edge, I would consider that being in the simplest terms, the point where the tips are widest. Even if its on the nose curve, concavity being curved back in, way past the end of the sidecut curve.

Running length, is not going to really be determined by snocad, its going to be wherever you design your mold to start curving up. If you have a cambered mold it's going to be that inflection point where the line switches from camber to nose/tail curve, its going to be fudged 1-2cm based on how much camber/rocker you have, how aggressive or mellow your tip/tail radius is, etc.

This is something that probably takes hundreds of test boards to get nailed, but for the purposes of building one board, Bend your tips a little bit BEFORE the end of your effective edge, or the point where your board is widest @ the tips = catch free tips and a nice easy ride. Make them equal, you MIGHT have something with a little more edge hold due to more contact point pressure, get it wrong you have a board that does this push/pull effect while you go down the hill on your edge, and you'll be hating life.

I didn't know that Rome was doing that. I don't like the terminology they are using, as it is not accurate. If any of the sidecut is in the shovel, it is not effective in a carve, and shouldn't be counted as effective edge. Weird.

So Doug, how visible is this area just a little mini rocker, or is it the same radius as the entire shovel?

doughboy I'm not sure what you mean, I'm assuming by "shovel" you mean the upcurve of the tips.

What happened to me was i built a couple boards, and put them in a mold that I did not design, and the running length of that mold was a bit longer than the design running length for my board. So the nose/tail were not bent until a cm or two beyond the widest part of the tips, made HUGE contact points.

I have since (after looking at the rome 5cm spec) started this tip bend before the widest part of nose/tail. I honestly dont know what rome means by "effective edge", I just assumed it was what they were considering the length of edge that is part of the sidecut, or everything inbetween the widest parts of the board, which is not necessarily the sidecut and can include the nose/tail flat shape curve. ie the inflection point would be before that.

I'm assuming for good edge hold you'd want these two values, the "running length" and "effective edge" as close as possible without the running length going beyond the effective edge, if you want to have the best edge hold. All i know is that we started bending them shorter, and it eliminated the ridiculous grabby problem.

When you say "is it a little mini rocker", are you referring to the couple cm of bend before the end of the effective edge? No I think it's part of the "shovel" or the nose/tail upcurve radius.

Best way to check it, is to take a board, lay it flat on flat surface, notice where the edge starts coming off the floor, might want to put weight on it to take out the camber, then take board, and slowly roll it onto the edge, if the part making contact with the floor is now beyond the part where it's lifting, then I would assume the RL is shorter than the EE. In our first boards this was backwards, and that's what I meant, which contributed to a super squirly, almost uncontrollable ride on ice and hardpack, picture magnetraction with the only contact points being @ the tips, you get this insane push pull effect, you initiate a turn and it jamms in so you go to the tail and the tail grabs and tries to straighten you out so your weight then goes forward again, repeat, its a mess.

I understand what you're getting at now.

You definitely don't ever want your shovel (tip rise) to start after the end of the sidecut. that would be hard to ride.

What I am getting at is that if the side cut extends in to the shovel, then even in a weighted out turn that bit of edge will probably not be doing much. The board will be a little bit looser, but maybe with a little sacrifice of edge stability? IDK. A lot of the alpine builders are rockering a little section before the shovel to reduce the grabbiness of their boards without sacrificing edge stability.

The difference between shovel and rocker, being that the amount of rocker can be slight, while the shovel is usually a pretty drastic radius.

I would suggest that you put the start of your shovel at the exact end of your side cut, but incorporating 5-10 cm of minor rocker before that point. This will loosen up your contact points, while increasing edge stability and reducing swing weight.

they're pretty loose now, but yea those are some good ideas

On the topic of this thread, I ended up contacting Rome to find out their position, and have been given written permission to use the dimensions as long as it's for educational purposes.

Some good off topic info here though guys cheers.

cool man, some of the guys at rome are pretty cool, a friend of mine from my home town worked for them for years as team manager, photographer, marketing, website, all kinds of stuff. Even designed a board or two such as the original Artifact I believe.

Yea like I said, I wouldn't just blatantly take their shapes and do the exact same thing, but their boards are really good so it makes a good start, and for benchmarking purposes. But I wonder how close can you be dimensionally before its really just a ripoff? Who knows, plus boards are all way more similar than not, i wouldn't be surprised if there's a K2 board out there with nearly the exact dimensions as a Rome, Burton, etc.

But yea just to make one, shit I have one off boards with Apocalypse graphics on them circa 1995, but never would I sell one.

I don't see the issue in taking their dimensions then changing them and selling the board, it's essentially a new board shape by then anyway. Especially if there's something about how the board rides that you really like, if you can find out what makes it that way then use it for your own purposes it's fine. These companies all do that to each other anyway.

Going off a catalog does give you the basic specs, however a lot of times the specs are fudged a bit, rounded up or down as well. I know I change the specs from actual CAD specs. Plus, it's pretty hard to figure out the sidecut radius since they are usually made up of multiple radii. Tracing an existing board to use as a template for the base will make the board 4mm wider anyways. Plus after finishing, the edge is thinner...might be quite a bit on the Rome board if it's from Elan...they seem to always hammer the hell out of the edges.
Effective Edge is the widest point of the board and raised above the contact/running length so it's part of the nose/tail. There is a radius that blends the nose/tail or shovel into the sidecut. This area is called either the blendzone or transition zone. You can have a 2.5cm difference from the effective edge to the contact point but only have a 1.5cm transition length from effective edge to the sidecut or you can make it 2.5...just depends on what type of ride.

For what it's worth in my first ski designs I have ended the side cut 4cm beyond where the tip and tail rocker should leave the snow. I saw some specs where the sidecut length was exactly equal to the running length (ie. widest point would be exactly at the conatct points with the snow). This worried me a bit that it would make a 'grabby' ski. I ended up fudging with the 4cm margin as I am also a bit concerned about tip relaxation. Hopefully with a bit of relaxation in the rocker the widest part of the ski is still just off the surface of the snow. I haven't really looked at my commercial skis to see if their sidecut ends somewhere in the shovel or not, but to do this seems to make sense to me.