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Help!!!: Boot + Binding = Balance Problems???

post #1 of 12
Thread Starter 

My Mom is an older solid upper intermediate to lower advanced skier with decent skills but limited angulation and flex ranges. She's currently in a Lange Comp 90 (I believe) that was fitted and adjusted last year by a reputable fitter (Rob @ Sun and Snow in Ann Arbor) to address arch/instep issues and control problems.

 

For several years she was skiing strong and balanced on 150 cm Volkl P60 SL World Cup Juniors with Marker 14.0 Piston Control bindings mounted on a demo track. Then, two (maybe 3?) years ago she purchased a pair of 163 cm Volkl Auras mounted with Marker Griffon bindings and has been skiing them constantly ever since, consistently getting faster, more aggressive, and more adventuresome. Friday, however, we had really icy conditions and she chose to go back to the P60s for the night, only to have her tips wander and chatter to an annoying and confidence busting degree. She stayed on the blues for the night and found she could mostly get the tips under control but she had to really drive forward aggressively and concentrate on maintaining tip pressure through each and every turn. To say she was a bit frustrated would be an understatement.

 

I know; 1) it could have just been the conditions, and 2) it's hard to tell without video and pictures of the equipment set up, but my gut reaction to this whole situation is that the heel lifts in her boots that keep her balanced on the Auras with the zero delta Griffon are causing an over-ramped situation on the SLs with the Piston binding.

 

Is this a very real possibility or am I just grasping at straws??? If I'm off track, can you suggest other possibilities?

 

If over-ramping really is the case, is it likely that a gas pedal can be put under the toe mounting area of the Piston demo plate to correct this?

post #2 of 12

it's certainly possible that this could happen. I'd expect that the Griffons are damn close to truly flat maybe 1mm down at the toe. The pistons are probably 5mm down, and I do think that you can shim that binding/plate (is it the one with the on/off switch for the piston?). Anyway, it is inexpensive to experiment with delta, so go for it and let us know what happens.

post #3 of 12

or have her take out the heel lifts and see what happens...

post #4 of 12

Take the heel lifts out.

no reputable boot fitter would put them in, if your guy did, find someone else.

post #5 of 12
Quote:
Originally Posted by trees View Post

Take the heel lifts out.

no reputable boot fitter would put them in, if your guy did, find someone else.


Wouldn't agree with that, don't drink the Kool-aid just because you read a few posts here that say don't use them.  

OP said mom was doing great with them on the other skis.

 

 

post #6 of 12

The ramp/balance thing can be tested empirically very easily and at almost no cost. Temporary gas pedal is an easy and inexpensive test to play with and of course removing the heel lifts is also a good experiment. Naturally, if the ankle range is very low, then the lifts should probably stay put.

 

JOOC.....have the skis (P-60's) been tuned recently?

 

SJ

post #7 of 12

Agree with Sierra Jim above.

 

Could be the conditions but it I suspect the difference in delta angle created by the stand height differential may be the culprit.  As Jim suggested you can easily slip a couple 3mm shims between boot and AFD on toe piece and see if that solves the issue!

 

Please understand that the heel lift inside the boot has a whole different purpose and affect than changing the external delta angle.  Changing the ramp angle inside the boot does not change the angle of the lower leg and where the knee plumbs over the ski, while changing the delta angle does not affect the net forward lean angle between the foot and leg it does affect where the knee plumbs over the ski.

 

If she has limited dorsiflexion, I would keep the heel lift (internal) and decrease the delta angle (external) by gas pedaling the boot (shimming under the toe piece or screwing a lifter plate to boot sole and routering the toe lug back to specs.

 

Bottom line you want to find the optimum delta angle if that is the issue and recreate that angle on the other skis by shimming under the toe piece if possible.

post #8 of 12
Thread Starter 

Thanks for the replies, guys.

 

I'd guess that she probably does have limited dorsiflexion, both from being "mature" and from numerous sprains while doing gymnastics, so I don't see the heel lifts going away.

 

Since I do lots of things myself (including recently tuning and waxing both sets of said skis wink.gif), and likely have some usable stock left over from my old cant strips, is there a big problem with attempting to install a gas pedal myself or should I take them to the local shop? Are we thinking around 4-5 mm?

 

@epic: Nope, no switch on this one. It's got the piston in front of the toe piece.

post #9 of 12
Quote:
Originally Posted by volklgirl View Post

Are we thinking around 4-5 mm?


Get a caliper and measure both sets of skis to see how much delta they have. I just measure between the AFD and the base of the ski, then the brake pad or wherever the heel makes contact to the base of the ski and subtract. Do that for both sets of skis and then you know how much shim to add.

post #10 of 12
Thread Starter 

Awesome, thanks!!

post #11 of 12

The reason that I asked about tuning was that the symptom you described can sometimes be traced to a ski that is too flat or has stone grinder or belt structure in the edges from a machine tune. If all you did was a little file work on the side edge then that's probably not a concern. OTH, if they have been on a machine since she last skied 'em well....then that might be at least a pale red (uhhhh......pink?) flag.

 

SJ

post #12 of 12
Thread Starter 

Nope, no machine tuning, just side edge work and a wax job.

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