where are you putting your boot centre line?

For discussions related to ski/snowboard construction/design methods and techniques.

Moderators: Head Monkey, kelvin, bigKam, skidesmond, chrismp

Post Reply
jonno
Posts: 11
Joined: Mon Jan 18, 2010 12:58 pm
Location: Chamonix

where are you putting your boot centre line?

Post by jonno »

so my question is are people mounting there boot centre on the centre of the skis turn radius or are you using some other point like say matching the ball of the foot to the center of the turn radius. I came up with a ski mid winter and after mounting some rental binding on it and testing different center mounting positions i discovered that for me the sweet spot was that the ball of my foot line up with the radius center on the ski.

Any thoughts? what have you guys being doing and have many of you tried different mounting positions? with what result. Is there a rule of thumb for mounting?

Input on this would be appreciated im interested so that i can incorporate it into the design of the ski from the begining and eliminate as much testing and guesswork as possible.

Any relationship or trends you have discovered in mounting lengh from the tip, relative to total lengh of your ski, expressed as a percentage? just a thought. could such a rule exist to govern say powder skis or carvers?

cool i await your responses eagerly. out.
skidesmond
Posts: 2337
Joined: Tue Apr 07, 2009 3:26 pm
Location: Western Mass, USA
Contact:

Post by skidesmond »

There's lots of discussion in the forum on that topic. Here's a recent discussion:
viewtopic.php?t=2395

Use the search function and you'll find many more.
jono
Posts: 121
Joined: Wed Oct 17, 2007 9:26 am
Location: denver

Post by jono »

I put my narrow point/radius center 55% from the front of the running surface. This is also the boot center point and the thickest point on the core. I don't ski backwards so I like this more traditional ratio.
I've noticed that I can shift the boot center from the radius center a little bit to change how the ski feels (forward helps make the ski lively and back deadens the ski but floats the tip). If the boot center is mounted too far away from the narrow point the skis can become really hard to ski with.
Finding the right spot to put the radius center and orienting the boot center can be tricky but when everything is aligned you can feel it.
jonno
Posts: 11
Joined: Mon Jan 18, 2010 12:58 pm
Location: Chamonix

Post by jonno »

thanks jono for that il give the 55 percent a try and check the previous forum discussions, sorry just being a bit lazy. cheers guys.
User avatar
Dr. Delam
Posts: 423
Joined: Thu Feb 01, 2007 10:07 am
Location: Truckee

Post by Dr. Delam »

I agree with Jono. I usually do my boot center and ski radius center at the same spot. This makes the most sense to me to have the narrowest part under my arch.

I also make this point at 55% from the tip for everyday skis. For a specialized pow ski I'll go 1% back for tip float.

Mounting a demo binding is not a bad idea to get a feel for the ski before mounting the real deal. You can dramatically change the way a ski feels by moving the mounting position. Usually two mounts is no problem as long as you space the holes accordingly.
jonno
Posts: 11
Joined: Mon Jan 18, 2010 12:58 pm
Location: Chamonix

Post by jonno »

ok 55 percent of running length sounds good on a traditional ski and even a bit further (56percent in DR delams case for a powder ski) but what about the relationship to overall length of the ski ?
My ski is 183 long with a running length of 130, which is short i know and a huge tip. so with the design at the moment i have boot center at 50 percent of running length because with the size of the tip it still makes for boot center at 56 percent of total length of the ski. if i go for 55 percent of running length and then add our huge tip(38cm by the way) i get boot center at more like 60 percent of total length which seems too far back , considering that with this huge tip and gradual rocker i should be able to mount a little further forward than a traditional ski so as to make it more maneuverable and agile and still maintain floatability.

Any thoughts? its kinda interesting. wish i had a small factory i could just punch out skis fast and test and tweek to my hearts content.

kinda feels like with rocker a lot of the rules kinda get tossed out the box and you just gotta see what feels right.
skidesmond
Posts: 2337
Joined: Tue Apr 07, 2009 3:26 pm
Location: Western Mass, USA
Contact:

Post by skidesmond »

freeloader wrote:.... wish i had a small factory i could just punch out skis fast and test and tweek to my hearts content.

kinda feels like with rocker a lot of the rules kinda get tossed out the box and you just gotta see what feels right.
We all wish that :) . Some else made the same comment about rocker skis... (Endre maybe?) But I think generally 55% is a good rule of thumb and a demo binding is a good idea so it will allow you to slide the binding to find the best spot.

I haven't built a rocker ski yet. But IMO I think you want the boot center to be at the narrowest part of the ski. So if the narrowest is at 50% that's you're boot center, 55%? that's your boot center. And using a demo binding as suggested can help you tune for the sweet spot.

There's lot's of opinions/discussions on the topic. But really, it boils down to, just do it.... test it... tweak it... do it again.

That's the fun of ski building!
Post Reply