What Is The BobTail Design?
A Flawed Axiom: Symmetrical Ski Design
Ski design has changed little from the crude boards that early skiers tied to their feet. Although today’s skis are made from advanced materials, the shape of nearly all alpine and telemark skis are relatively simple and symmetrical. That’s great for skiing straight lines but this design axiom becomes more flawed as the skis edge and turn.
Skis are the instrument of interaction between skier, slope, and snow. It’s an ever-changing equation of weight and force to manipulate the edges, both inside and outside of the ski to affect control. The control dynamics of most skis is anything but symmetrical once they’re on the feet of a turning skier.
Think of a center point for a circle with the skier carving the two lines of the radius with the skis. The circle made from the inside ski will be smaller than the one made by the outside ski. The tighter the turn, the more significant the difference will be in the two tracks. This is the inherent problem with using the same inside/outside length in traditional skis – they’re always going to be mismatched.
To make matters worse, the weighting of the skis adds additional control problems for the inside edge in a turn. Symmetrical skis have more surface area to distribute the skier’s weight on the inside edge when considerably less surface area is actually needed in a turn. That makes it even more difficult for the skier to use the inside edge.
As a ski instructor, Scotty Bob thought a lot about these fundamental flaws inherent to symmetrical ski design and how it made turning more difficult for alpine and telemark skiers of all skill levels. Using a hack saw to modify traditional skis, he began experimenting in the late 90’s with different lengths and side cuts on each side of the ski to improve outside edging and weighting. The results were immediately apparent in creating a pair of skis that were dynamically balanced and turned effortlessly.
The Revolutionary BobTail Design
The BobTail ski design by Scott Robert Carlson (ScottyBob) is a ski with inside and outside edges of unequal lengths. You’ll also notice that the apex of the side cut curve on the shorter edge is forward of the apex of the longer edge. This innovative design was first implemented in our line of ScottyBob telemark skis.
Telemark skiers have two very distinct foot positions. The downhill foot position is with the sole of the boot flat on the ski applying pressure near boot center. The uphill foot position is at toe center and pressures the skis much further forward. Ideally, the two edges of a ski should be designed for these two different points and where control pressure will be applied. That’s exactly how ScottyBob skis are designed and why they truly maximize skier control and turning ability.
Scotty Bob’s innovative design is like wearing two pairs of skis, on a turn you have a shorter ski for the insider edge and longer ski for the outside edge. It’s no gimmick. The result is absolutely amazing. Now there is a ski that greatly increases your leverage with full use of both inside and outside edges. Skiers of all skill levels will immediately experience significant improvement in both control and turning ability.
Problems with Mounting Symmetrical Skis
In a symmetrical ski the boot center is for both edges. Mounted the skis on the boot center mark and the downhill ski works the way it was designed. Unfortunately the uphill ski is weighted considerably farther up from boot center. This problem is even more accentuated for telemark skiers.
First, the apex of the side cut is at boot center and you are pressuring the ski forward of that point. Second, boot center is generally located 55% back from the running length of the edge. When you pressure the toe of the boot, the edge is now being pressured approximately 45% back from the running edge. The result is one ski always working the way it was designed but the other having inefficiencies because it’s mounted in the wrong place.
Another common mounting technique for symmetrical skis is use of cord center. This entails moving the bindings back to compensate for the normal weighting of the uphill ski. The use of cord center will always result in the downhill ski being weighted behind boot center. The uphill ski works a little better, but it’s still not located in the right spot. The downhill ski is now even further out from the proper mounting point so both skis are setup wrong.
In the BobTail design, the uphill ski edge is designed to address this common mounting problem. The apex of the side cut is also shifted forward so it’s under the toe area of the boot. The length of the uphill edge is shorter, so when you pressure that area of the ski you’re 55% back on that running edge – exactly where you need to be.
Another benefit of a shorter uphill edge is the weight distribution between both skis. The downhill ski will get more of the skier’s weight because of bio-mechanics. It’s just harder to pressure a uphill ski. With a shorter edge length on the uphill ski it takes less force to exert pressure because the surface area and edge length is decreased.
In summary, with symmetrically shaped skis, one or both of the skis will always be mounted improperly. With the BobTail design, both skis are always mounted correctly. That makes a huge difference in your skiing. If you haven’t skied a pair of ScottyBob’s then you’ve never experienced the thrill of having both skis mounted properly and working together effortlessly with silky smooth transitions between every turn.
Alpine BobTail vs. Telemark BobTail
If you’re an alpine skier you want a pair of ScottyBob alpine skis. They’re specifically designed for alpine bindings, mounting and skiing. Although we started as a telemark ski company, from the very beginning alpine skiers begged us to translate the BobTail design into a ski they could use for better control and ease of turning. We introduced alpine models in the spring of 2006.
Initially we’d tested our telemark skis with alpine bindings and they received good reviews, but we knew that an alpine ski would require different design characteristics.
When the uphill foot position shifts on a telemark ski, the center of weight moves forward approximately 14 centimeters. That affects the tail delta for a telemark ski considerably and it ends up being about 28 centimeters. Even expert alpine skiers found themselves in the “back seat” of our telemark models because alpine bindings and mounting made it too easy to apply pressure to the rear of the ski. The tail delta on ScottyBob telemark skis is too excessive for alpine mountings with the uphill ski tending to veer uphill when the skier gets into the back seat.
An alpine skier’s uphill ski tends to pressure forward, but not nearly to the extent of a telemark skier. After a lot of alpine R&D we came up with a design based on about half of the forward shift of a telemark ski. This also requires a significant reduction of the tail delta to give alpine skiers the control they need in the back seat. They’ll still fell a bit of a penalty for being there, just enough to encourage them to move their weight forward, without getting spanked in the process.
The design modifications we introduced for ScottyBob alpine models have received rave reviews. Our alpine skis carve better, the uphill ski has a stronger hold (because of the shorter edge) and transitions are quick and smooth. Alpine skiers have found our design really helps them stay centered over the skis. That translates to better skiing with less effort.
Don’t take our word for it. Read through actual reviews of our alpine and telemark skis by skiers of all skill levels. The reviews are here on our website and they’ll give you an idea of how exhilarating it can be to ski a pair of hand-made ScottyBob skis.
Just remember, if you’re an alpine skier make sure your ski is specifically designed for alpine skiing. While ScottyBob telemark and alpine skis may look alike there are considerable differences in the two designs based on the type of mounting as explained above. Don’t buy a telemark ski for alpine skiing or you’ll compromise control and performance potential.
This is for people who want to go beyond customizing their topsheet graphics. And delve into the science of designing their own personal ski shape, it may not be for everyone. But for the some who always wanted to say “this is my ski and I designed it!”.
At ScottyBob’s SkiWorks we try to make the process as simple as possible, for the client to get their dream ski made. Unlike other companies that make you fill out forms for hours. Asking you questions from “What do you like to have for breakfast?” to “what color is your underwear?”. Or companies that make you fill out spreadsheets that could make your head spin, with a lot of numbers that keep on changing every time you put in a new one.
At ScottyBob’s we keep to the old engineering saying “Keep It Simple Stupid” or KISS. Here there is only six things you have to decide on to get your own ski designed and then we do the rest of the work!
Step One: Telemark or Alpine?
Do you want a Telemark Ski or an Alpine Ski?
This is very important, as discussed in the design page of this website. The Bobtail design is very dependent on what ski discipline you are going to use it for.
Step Two: Ski length
What length of ski do you want? This is a question that only you should be comfortable in answering. We get a lot of people asking us about the size of the ski they should get. To be honest, we haven’t skied with you. All we can do is talk to you about how you feel about different lengths that you skied. Some worry about the Bobtail design is going to feel longer or shorter than a symmetrical ski. Don’t worry about it, if you ski a 177cm ski now a 177 BobTail is going to feel the same lenght.
So the first step is to pick the length of the ski in centimeters.
Step Three: Picking Two of Three Dimensions
There are three dimensions we use when designing a ski they are: Sidecut Radius, Waist Width, and Tip Width.
Sidecut Radius – Is the theoretical circle when the ski is put on edge. The smaller the number the smaller the circle, like wise the larger the number the larger the circle. For example, a 14 meter ski is very quick turning and always wants to be on edge. Where a 30 meter ski is for long turns and doesn’t mind if you run them flat.
Waist Width – Is the narrowest part of the ski. You have to ask your self what you are looking for in a ski here. A ski with a 77 mm waist is going to be quick edge to edge, but it will have little float in powder. Where as a 110 mm waisted ski will be hard to get on edge, but will have a lot of float in powder.
Tip Width – Is the largest width of the tip. A large tip width can help the ski in powder to ride up on the snow and be more stable in busting through the crude.
In step three, your job here is to pick ONLY TWO of the THREE dimensions. Why you ask? Because one will have to remain a variable and will be calculated by our state of the art program. So if you pick a ski with a 16 meter sidecut and a 96 mm waist the tip dimension will be calculated. Or if you want to pick the waist of the ski to be 78 mm and the tip to be 125 mm the sidecut radius will be calculated.
At this point, your are done designing your ski. You don’t have to be a rocket scientist to get a ski that you have been dreaming of , that’s why we use the KISS system.
This year we are going a couple of steps further than we have done in the past, we added steps four and five into the equation. Now you can pick out the shape of the tips and tails of the skis.
Step 4: Tip Shape
(Free on custom dimension skis, $50 on standard skis)
We are offering four different tip shapes for custom dimensions this season and here we will discuss the pros and cons of each.
Pros – looks really cool and chicks dig them.
1.When skiing, if the uphill ski gets on the downhill tip. It’s a flat surface and the uphill ski will just remain at rest on that surface, so you will have to concentrate on removing the uphill ski for the down hill ski your self.
2.Because of the sharpe angles in the tip shape, we have to use a three piece edge to make the shape. There fore the corners of the tips do not have any edge protection.
Pros – Again looks really cool and chicks dig them :-).
1.Pointed tip helps the uphill ski slide of the downhill tip easily
1.Looks a little geeky
Classic tip –
Pros : nothing really, Just our Classic tip
Round Tip –
Pros : A lot of surface area to help climb out of the powder
Cons : Same as the flat tip, the uphill ski can get caught up on the downhill ski.
Step 5: Tail Shape
(Free on custom dimension skis, $50 on standard skis)
1.The skis can stand up with less chance of falling over
2. Metal edge is inserted to prevent base peel up when sticking the skis into the snow
3.Easier to attach skins on the skis
1.The inside of of the tail kicks can ride up on each other during skinning and turning
1. The skis can stand up with less chance of falling over
2.Metal edge is inserted to prevent base peel up when sticking the skis into the snow
3. Easier to attach skins on the skis
4.With the cut on the tails there is less chance of the tail kicks to ride up on each other
1.It depends if you like the looks or not
1.Classic round tail shape
1.Skis tend to fall over when stood up on end(Might kill your cat)
2.Hard to attach skins on skis
3.No metal edge to protect ski base when sticking into the snow
So here are the five steps to design you own custom dimensioned ski.
Step 1 : Is it an Alpine or Telemark Ski?
Step 2 : What is the length of the ski you want?
Step 3 : Pick TWO of THREE dimensions(Sidecut Radius, Waist Width, Tip Width)
Step 4 : Pick Tip Shape
Step 5 : Pick Tail Shape
And now you are done and the rest of the work is up to us to bring your dream ski into existence!