- Joined
- Aug 24, 2017
- Posts
- 364
There is an interesting review of Renoun 98 mm ski over at Blister gear reviews.
Basically, the (very experienced) skiers found the ski to me very, very stiff, almost impossible to bend into turns for the great majority of potential skiers. That's not the whole story, or the end of the story, but that was a first impression.
I know some of the narrower skis are popular in this community, so I thought I would post some thoughts/questions.
The technology is interesting. I did some quick research about non-Newtonian polymers; there's some good simple information on Wikipedia. Basically, it seems like these substances change viscosity as shear forces increase. If you compress them or stretch them slowly they stay compliant; if you compress them or stretch them very quickly they become more rigid. There also appear to be other substances that do the opposite (become less viscous as shear forces increase). They are actually pretty common, and include everyday substances, like cornstarch and blood, as well as materials used in wide range of industrial and other applications.
In this case, it seems as if the ski has been designed so that, as forces on the ski increase, the shear forces on the polymer increase, and the polymer becomes more resistant to deformation, making the ski more rigid and possibly more damp. That theory appears to be supported by your experience; the ski is lightweight and hand flexes soft to moderate, but, the faster you go, the more resistant it is to deformation, or, more simply, the harder it is to bend, or, even more simply, the harder it is to turn. It sounds like, in the case of the 98 mm skis, it's too hard to turn, at least for the great majority of people who will ever ride this ski.
Here are some questions I had about the technology in general:
What are the actual mechanical properties of this polymer? As you increase shear forces on the polymer, how does the resistance to deformation change? Is the change linear, progressive, regressive, and so forth. In the case of the 98 mm skis, it almost seems like there is an "on" and "off" with the ski, i.e. at slow speeds, or not skiing at all, it remains soft, but then, with even a little speed, it quickly ramps up to very stiff. This could probably be adjusted by changing the composition, amount, and placement, of the polymer, to make it more or less progressive, and so on.
Then there is the whole question of how the polymer interacts with the other materials in the ski, and the ski shape. If the other materials were modified, or if the side cut, tip shape, and rocker profile were changed, would the ski initiate turns more easily?
As i said, the narrower more piste-oriented skis from Renoun seem popular, so some combinations of the right polymer, the right other materials, and the right shape, seem to work well.
One thing is for sure: if these polymers become common in skis, then this will introduce another huge variable to ski design. It's hard enough to understand how traditional materials, side cut, tip and tail shape, and rocker profile effect ski performance, to say nothing of adding different degrees of stiffness at different speeds.
I can't imagine that other manufacturers, especially the large manufacturers, aren't experimenting with this technology.
Any ideas?
Basically, the (very experienced) skiers found the ski to me very, very stiff, almost impossible to bend into turns for the great majority of potential skiers. That's not the whole story, or the end of the story, but that was a first impression.
I know some of the narrower skis are popular in this community, so I thought I would post some thoughts/questions.
The technology is interesting. I did some quick research about non-Newtonian polymers; there's some good simple information on Wikipedia. Basically, it seems like these substances change viscosity as shear forces increase. If you compress them or stretch them slowly they stay compliant; if you compress them or stretch them very quickly they become more rigid. There also appear to be other substances that do the opposite (become less viscous as shear forces increase). They are actually pretty common, and include everyday substances, like cornstarch and blood, as well as materials used in wide range of industrial and other applications.
In this case, it seems as if the ski has been designed so that, as forces on the ski increase, the shear forces on the polymer increase, and the polymer becomes more resistant to deformation, making the ski more rigid and possibly more damp. That theory appears to be supported by your experience; the ski is lightweight and hand flexes soft to moderate, but, the faster you go, the more resistant it is to deformation, or, more simply, the harder it is to bend, or, even more simply, the harder it is to turn. It sounds like, in the case of the 98 mm skis, it's too hard to turn, at least for the great majority of people who will ever ride this ski.
Here are some questions I had about the technology in general:
What are the actual mechanical properties of this polymer? As you increase shear forces on the polymer, how does the resistance to deformation change? Is the change linear, progressive, regressive, and so forth. In the case of the 98 mm skis, it almost seems like there is an "on" and "off" with the ski, i.e. at slow speeds, or not skiing at all, it remains soft, but then, with even a little speed, it quickly ramps up to very stiff. This could probably be adjusted by changing the composition, amount, and placement, of the polymer, to make it more or less progressive, and so on.
Then there is the whole question of how the polymer interacts with the other materials in the ski, and the ski shape. If the other materials were modified, or if the side cut, tip shape, and rocker profile were changed, would the ski initiate turns more easily?
As i said, the narrower more piste-oriented skis from Renoun seem popular, so some combinations of the right polymer, the right other materials, and the right shape, seem to work well.
One thing is for sure: if these polymers become common in skis, then this will introduce another huge variable to ski design. It's hard enough to understand how traditional materials, side cut, tip and tail shape, and rocker profile effect ski performance, to say nothing of adding different degrees of stiffness at different speeds.
I can't imagine that other manufacturers, especially the large manufacturers, aren't experimenting with this technology.
Any ideas?
