BOOT BOARD (ZEPPA) RAMP ANGLE VS. BOOT SIZE


It is becoming clear, the angle the boot board (zeppa) establishes for the skier’s foot relative to the ground, is vitally important to the ability to balance and function on skis. Therefore, knowing boot board angle (ramp angle) and skier preferences should become part of every boot setup and purchase. Yet there appears to be a fundamental error in the understanding of ramp angle in boots. This is evident when someone states, for example: “The head Raptor has a ramp angle of 4.5 degrees”. The statement may only true if the angle is linked to the boot size.

There are production controls applied to boots just as controls and standards are applied to all other things mass produced. In boots, it means the first prototypes are designed to a specific size (generally Mondo 26). All other sizes are scaled up or down from it. Each Mondo size is a change of one centimeter. Zeppas are fixed in both rear foot and forefoot height in the prototype standard. Only the zeppa length changes as boot size changes.

It means; if the prototype size is twenty six, the zeppa of a twenty three is three centimeters shorter with the same toe and heel heights. Therefore, the ramp angle of the zeppa of a twenty three is steeper than the ramp angle of the zeppa of a twenty six. Since many women’s boots are scaled from the twenty-six Mondo standard, boot set-up problems can be more difficult to solve for women than for men. This is the reason women are more adversely affected by boot configuration than men. The graphic below compares the boot board (zeppa) ramp angles of larger and smaller boots to the standard Mondo 26 boot.

Zeppas Mondo 26

 

Bindings obviously confer the same effect, since with most models heel height is greater than toe height. As the heel and toe change distances from each other according to boot size, binding angle (delta) changes and its angle is additive with the boot ramp angle to determine gross equipment angle as shown in the graphic below. Binding delta has a double effect, since as delta increases boot cuff angle relative the ground also increases.

Zeppas Mondo 26 bindings

When talking about boot boad ramp, we should include the boot size or always use the ramp of the Mondo 26 as a known reference.


Lou Rosenfeld has an MSc. in Mechanical Engineering with Specialization in Biomechanics earned at the University of Calgary Human Performance Laboratory. His research was titled, “Are Foot Orthotic Caused Gait Changes Permanent”.

While at HPL, he assisted with research on the effects of binding position for Atomic, and later conducted research for Nordica that compared Campbell Balancer established binding position to the Nordica factory recommended binding position.

Lou is one of the invited boot-fitters on the EpicSki forum “Ask the Boot Guys” and has authored articles on boot fit, balance, alignment and binding position for Ski Canada, Ski Press, Super G, Calgary Herald, and Ski Racing, USA. He is a CSIA Level 2 instructor and CSCF Level 1 coach. He currently resides in Calgary where he owns and operates Lou’s Performance Centre. A selection of his articles may be found at www.Lous.ca.

One comment

  1. Excellent presentation on boot length and the binding’s effect on net ramp. Anyone that is going to experiment with lowering their ramp angle needs to be aware that they will have to do something about the restriction on ‘ankle glide path,’ the ability to flex their ankles within the ski boot or they may end up with a false conclusion. Again, I didn’t have the smarts to start with the fact that the ski boot locks up the ankle and also ‘race fit’ etc. restricts all normal foot function. So my approach to not being able to flex my ankles enough to get out of the back seat was to raise the ramp angle because it does 2 things; first it ‘artificially’ gives the skier more forward lean without using up the limited ankle flex available thus getting them out of the back seat and second, from that position I found I could ‘drop’ into the tongue of the boot using body weight rather than the tiny muscles in the front of the shin that aren’t designed for bending rigid plastic ski boots. As I removed the obstacles to foot function, first by trial and a lot of error on my own and then with the help of this blog in regard to ankle glide path, allowing toe spread, and removing arch impediments I have greatly reduced my ramp down to a third of what it was at its’ literal zenith. The trouble with starting within a boot with too much ramp in the zeppa, one has to really tighten the boot cuff to prevent falling forward out of the boot. This is what David addresses before the skier steps into the bindings and those experimenting with ramp angle must do so also. I originally improved my fore/aft ‘balance’ by increasing the ramp angle but it kept my feet locked up or even increased that issue. Everything has to be fixed where the problem is to get the optimum results; adding oil to the car’s engine won’t help if the gas tank is empty.

    I’ve been playing with body position while running this summer. Due to my knee issue the only way I can run without stressing the knee is to land on the ball of my foot; forefoot strike. Going down hills this has been fine but I started playing with the position of my COM due to a discussion with a friend. I discovered that I was running downhill very much like walking down steps until I lowered my COM and that really smoothed out the foot strikes. What I realized is that in a sense I’m stepping down as if my foot is ramped but adjust it according to the slope and needs. Thus I can see why there needs to be some ramp in the ski equipment for going downhill but the industry has gone way overboard with net ramp and forward lean because someone decided to not bother with allowing natural ankle movement in ski boots. I tried to find my last pair of leather boots to see what was underfoot in them, but unfortunately had no luck. I have noticed for years from seeing old pictures of skiers in leather boots, how they flex normally like other sports. That still didn’t make me figure out that we should do likewise in ‘modern’ plastic ski boots because I believed they were made and fitted by experts that knew what they were doing. Thanks David for helping me get over that misconception!!

Comments are closed.