Hey crew,
Been pondering on how to convert effective edge data to running length and vise versa.
The way I thought it should work is running length is basically the length of the segment of the circle used to derive the sidecut. In which case we get the sidecut radius and the running length, estimate the angle of the segment, and then calculate the length of the sidecut, which is effective edge.
Say "x" is running length, R is sidecut radius. Then sin (a) = (x/2)/R is the sine of 1/2 the angle of the segment. 2 x arcsin (a) will give us the angle. Then 2 x arcsin (a) / 360 is the sidecut proportion of the circle. Multiply that by 2 x pi x R, and we get the effective edge from running length.
The problem is that my calculations do not agree with any data supplied by manufacturers. Anyone knows how they calculate it in the industry?
Running length vs effective edge - conversion
Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp
conversion factors
anticipating some conversion factor discussion, there are a few floating around. such as 0.88 for skis and 0.96 for snowboards. However, I found these rules of thumb to be very unreliable...
OK cool. I'm definitely no mathematician, but I'm gonna guess and say that it can't be so easy to come up a simple formula if you want to be exact, since I am 99% sure that lots of skis sidecuts' are actually not just simple circular arcs, despite the fact that you often see stuff like "16m radius" sidecut.
Just to complicate things...
The discussion above attempts to define 'effective edge' in geometric terms, which is certainly useful in many ways. But, in a more practical sense, effective edge can be defined as the length of edge that is 'engaged' in the snow mass when the ski is rotated up on it's edge in a turn. Under this definition, the length of the effective edge is variable, depending upon the snow conditions. A ski that is placed on edge on very firm snow (or ice) is going to have a different effective edge length than the same ski placed on edge in 2 inches of softened corn, because in softer snow, portions of the tip and tail curve are effectively engaged in the snow mass. As ski design moves more and more into the realm of early rise tips, the length of the tip and the shape of the tip curve can greatly effect how much of the ski edge is engaged in the snow in a turn. All of this, in turn, significantly effects the optimum location for the binding mount.
my .02 cents worth,
G-man
The discussion above attempts to define 'effective edge' in geometric terms, which is certainly useful in many ways. But, in a more practical sense, effective edge can be defined as the length of edge that is 'engaged' in the snow mass when the ski is rotated up on it's edge in a turn. Under this definition, the length of the effective edge is variable, depending upon the snow conditions. A ski that is placed on edge on very firm snow (or ice) is going to have a different effective edge length than the same ski placed on edge in 2 inches of softened corn, because in softer snow, portions of the tip and tail curve are effectively engaged in the snow mass. As ski design moves more and more into the realm of early rise tips, the length of the tip and the shape of the tip curve can greatly effect how much of the ski edge is engaged in the snow in a turn. All of this, in turn, significantly effects the optimum location for the binding mount.
my .02 cents worth,
G-man
-
doughboyshredder
- Posts: 1354
- Joined: Mon Sep 17, 2007 7:37 pm
-
MontuckyMadman
- Posts: 2395
- Joined: Fri Jun 20, 2008 9:41 pm
I disagree. If you assume the average rider is in fact an average skier riding blue groomer runs at a resort that has like a 25 degree slope than thats where progressive sidecuts, splines and combined arcs make all the difference. A better skier can slide on whatever side cut or not.CFO wrote:hey webboy... I am just looking for a simple circular symmetrical sidecut formula. From my experience, all these progressive sidecuts and stuff dont make much difference for an average rider.
For instance these new progressive side-cuts with early taper make all the difference for my girlfriend to be able to ride pow and groomers with the same sticks, and has helped to greatly accelerate her learning curve.
I think the same could be said for most riders entering the sport. The learning time has been shortened greatly by these new shapes, not just the old symmetrical radial sidecut.
At least that's what I see.
-
doughboyshredder
- Posts: 1354
- Joined: Mon Sep 17, 2007 7:37 pm
From eternal snow:
aha, and here may be the answer, thanks to snowboardworld.info http://snowboardworld.info/snowboarding ... -Edge.html:
Effective Edge
Effective Edge - The length of metal edge on the snowboard which touches the snow; it is the effective part which is used to make a turn. Therefore, it does not include the edge of the tip and tail. The effective edge is in contact with the snow when the board is in a carved turn. A longer effective edge makes for a more stable, controlled ride; a shorter effective edge makes for a looser, easier turning board.
I just don't see how these two things are different, at all. Unless you are riding on something with tbt, but then your effective edge would be shorter than the running length.Running length - The range of the bottom of the snowboard that comes in contact with the snow.
aha, and here may be the answer, thanks to snowboardworld.info http://snowboardworld.info/snowboarding ... -Edge.html:
Effective Edge
this last explanation makes the most sense to me, and if that's what you're thinking then there would be a formula, but it would be dependent on the type and radius of the sidecut.The effective edge measures the length of edge between the nose and tail of the board that is in contact with the snow. It is similar to running length, but measured along the curved edge rather than in a straight line, making it a slightly higher number.
-
doughboyshredder
- Posts: 1354
- Joined: Mon Sep 17, 2007 7:37 pm
Irrelevant to the question or not,MontuckyMadman wrote:I disagree. If you assume the average rider is in fact an average skier riding blue groomer runs at a resort that has like a 25 degree slope than thats where progressive sidecuts, splines and combined arcs make all the difference. A better skier can slide on whatever side cut or not.CFO wrote:hey webboy... I am just looking for a simple circular symmetrical sidecut formula. From my experience, all these progressive sidecuts and stuff dont make much difference for an average rider.
For instance these new progressive side-cuts with early taper make all the difference for my girlfriend to be able to ride pow and groomers with the same sticks, and has helped to greatly accelerate her learning curve.
I think the same could be said for most riders entering the sport. The learning time has been shortened greatly by these new shapes, not just the old symmetrical radial sidecut.
At least that's what I see.
I agree completely. Especially magnetraction and rocker type stuff. It helps beginners more than anything.