In general, you mount the bindings in a different position on the ski depending on whether the ski is a striding oriented xc type of ski or a downhill oriented telemark type of ski. For most backcountry skis in between, you need to decide on a compromise between the 2 extremes, such as pins on chord center.
There are 3 basic mounting positions to consider:
Once you have established your pin line, you can have a qualified ski technician mount the bindings. Or, if you can live the consequences of your own decisions and mistakes, you mount them as described in the essay on mounting bindings.
If you come from an alpine skiing background, you will find that this mounting position looks wrong because it puts your boot sole further back than the common location for alpine boots.
Of all of the mounting positions, this is the easiest to determine. You can find the balance point by placing the base of the ski on a screw driver blade or a ruler’s edge and moving it until you find the exact location where the is balanced.
I will typically do this for both skis in a pair and compare the balance marks. If there is any variation between the 2 skis, I typically split the difference.
Once the balance point has been found, mark the top sheet of the ski with a felt tip pen.
This position will make the ski balanced enough to keep the tips down when striding. It also puts more ski out in front of the bindings compared to a mid-sole style mount, which will allow the ski tips to rise up better when powder skiing. However, this mounting position may not give the best hardpack performance.
Opinions differ on how to locate cord center. Most people do it this way: Attach a tape measure to the tail of the ski and pull it tight directly to the ski tip, creating a “chord”. Done correctly, the tape measure will form a low-angle ramp from the tail straight to the very tip of the ski. NOTE: The tape will be above the ski and will NOT go around the curve of the ski at the tip. This is the chord length.
Now, divide the chord length by 2 and measure that distance from the tail of the ski flat on the top of the ski. Mark this location as the chord center.
Skis have a sweet spot and on alpine skis, there is usually a marking on the top deck or side wall that marks the spot where the center of the alpine boot should be located.
Locating the correct sweet spot is more problematic for telemark skiers because their weight is applied by their boot center on the front foot, while it's applied by the ball of the foot on the rear ski. This means at least one foot is not pressing on the ski in the optimal position.
This is further complicated by the fact that binding position can affect the turning performance of a ski. A more forward position puts more pressure on the ski tips, making the ski initiate turns more quickly. More rearward, and the ski becomes more stable but less responsive. Hence we get the general rule that one should move the binding slightly forward for hardpack and slightly rearward for powder or cruising.
Finally, a person's build can have an effect. People (like me) with really large feet have a bigger difference between their ball of foot position and their mid sole position. As a result, it is common to move the bindings slightly forward to compensate. Similarly, people who carry more weight in their hips have a center of gravity that is slightly to the rear compared to folks who are more top heavy. As a result, it is not uncommon for women to benefit from a slightly forward position.
So, what does all of this mean? Well, it means a few things. First, it means that for better, more alpine style performance, you need to identify the mid-sole location where the center of the boot is aligned with the boot center mark on the top of the ski. This is especially true for hardpack telemark skiers who typically carry more weight on their lead foot.
Second, it means that because we are talking about telemark, not alpine, you must also take into account where the ball of your foot is.
Third, it means that you must balance and compromise between the mid-sole and the ball of foot positions according to your preferences.
The Telemark Tips web site has some good advice for finding the right binding position for downhill oriented tele skis. Try looking on their Dr. Telemark page.
As an alternative, Dana Dorsett posted the following advice on the skivt-l mailing list:
OK, now for the head-scratchy part; where to mount 'em...
- Press the bases flat against one another and mark the sidewall where the bases first separate at both the tip and the tail.
- Measure the distance between the two lines (the "running length") and make a line on the topskin equidistant between the tip & tail marks you just made.
- Measure the distance on the sole of your boot between the center pin-hole and the back of the heel. ("sole length" measurement.) Then mark the edge of the sole at the midpoint of your sole length.
- Mark on the outside of the boot exactly where you think/feel the center of the joint just behind your big toe is (the ball of your foot).
- Align your Ball of Foot mark with your running-length mid-point line and compare your "mid sole" mark to the alpine mid-sole (might say "mitte Schuh" or some Teutonic sumpthin' on Volkls) on the ski graphic - it should be pretty close, but probably not exact. Mark a line on the ski where your mid-sole mark on the boot is.
- Hook a tape on the tip of the shovel and measure the distance to the tail. (Chord length) and mark a line on the topskin equidistant from tip & tail (Chord center.)
- Align the boot pin holes on the boot with your Chord center mark, and compare the mid-sole mark to both the measured and the manufacturer's mid-sole mark is. Make a new mark on the ski where your boot's mid-sole mark is.
- Then, take your pick: The forward-most mid-sole mark will be the turniest- mount 'em there! If it's all over the place, go with your first measured mark (based on the running length), which will probably turn out to be the best compromise. The rear-most will be the best for high-speed cruisin'...
Copyright 2004 by David Mann