Skisix

Booting up
Skier
Joined
Dec 1, 2018
Posts
34
I've always been a nervous about mounting my own bindings w/o proper gear (template/jig etc), but I just picked up a set of used skis for use as rock skis this season and want to re-mount the existing bindings myself to keep costs minimal. The problem is, the skis are crappy Head BYS rental system skis that don't provide a recommended mount point. My current plan is to measure tip-to-tip, and pick a point a few cm back from center. My powder skis have the mount line 2.5 cm back from center...any thoughts on whether this is a reasonable target?
 

cantunamunch

Meh
Skier
Joined
Nov 17, 2015
Posts
8,391
Head BYS - are they flat (no bindings)? Have they been drilled already?

Taking the mount point of one ski and carrying it over to a different design, make, model is a good way to get in trouble fast.

If the Heads have any previous drilling, I'd use that as a rough guide. Otherwise, I'd use the sidecut.
 
Thread Starter
TS
S

Skisix

Booting up
Skier
Joined
Dec 1, 2018
Posts
34
Bindings are mounted already, but they were set up for HUGE boots (like size 35 or something enormous) so I don't know how well that will translate :(

In terms of sidecut, is it typical for the boot midsole to be exactly aligned with the min width? I just used a caliper on my powder skis and that seems to be the case for one data point...
 

cantunamunch

Meh
Skier
Joined
Nov 17, 2015
Posts
8,391
Bindings are mounted already, but they were set up for HUGE boots (like size 35 or something enormous) so I don't know how well that will translate :(
Click the binding shut (as in in-use) and find the approximate midpoint - drop that to the ski. Compare that to the waist-midpoint you find by measuring sidecut.

Mounted for big boots is good - the error in measurement will be averaged over a larger quantity. Boot center should be on the same place.
 
Thread Starter
TS
S

Skisix

Booting up
Skier
Joined
Dec 1, 2018
Posts
34
Ah, got it. A quick measurement puts the boot center about 2 cm behind the minimum waist. So, I assume it makes sense to keep the boot center point the same after the remount?

Thanks for the help!
 

Noodler

Back in the game! :)
Skier
Joined
Oct 4, 2017
Posts
1,827
Location
Denver, CO
My current thinking/approach on this is to match the boot midsole mark to the narrowest point of the sidecut of the ski (minimum waist width). This typically is also the point where the ski is the thickest in its side profile.

With today's rockered designs, this seems to be the only truly reliable way to find a good starting point. Using a binding with fore/aft adjustability will provide some fine tuning if necessary.
 

Noodler

Back in the game! :)
Skier
Joined
Oct 4, 2017
Posts
1,827
Location
Denver, CO
BOF over CRS, that's the basic principle for mounting bindings. There's a bunch of details here.
But absolutely does not work for any ski with any degree of rocker/rise in its profile. BoF over CRS is relegated to race skis only at this point.
 

Doug Briggs

Skiing the powder
Industry Insider
Pugski Ski Tester
Joined
Nov 9, 2015
Posts
4,233
Location
Breckenridge, CO
Set the existing binding to your boot, put the boot into the binding and then mark the ski where your boot's center mark is. easy peasy.

Edit: I'm assuming the crappy rental system includes rental bindings.
 

Doug Briggs

Skiing the powder
Industry Insider
Pugski Ski Tester
Joined
Nov 9, 2015
Posts
4,233
Location
Breckenridge, CO
I'm curious. @razie provided a link to determine how to arrive at BOF over CRS. In it it says:

determine the BOF
  • place your foot in boots
  • bang on the sides with a screwdriver until you determine where the BOF is and mark it on the side of the boots.
Please define where on my foot where the BOF is. Is it the widest part? Is it where my 5th metatarsal meets the phalanges proximales? ???



Here is a definition I found:

ball of foot

n.
The padded portion of the sole of the human foot between the toes and the arch, on which the weight of the body rests when the heel is raised.
I don't think I'm not going to feel that padded portion on the sole of my foot by tapping with a screwdriver handle.
 

razie

Sir Shiftsalot
Skier
Joined
Jan 18, 2016
Posts
925
Location
Ontario
But absolutely does not work for any ski with any degree of rocker/rise in its profile. BoF over CRS is relegated to race skis only at this point.
Why not? When you determine the CRS you're using the contact points, so looking at just the cambered portion, which is a good approximation of how the ski will feel. Of course, different rocker profiles will engage differently in soft snow and it also depends how you ski it - higher angles engage more of the ski, so it's not an exact science - it's just a starting point... but you bring a good point: type of ski and where you ski it influences the decision... how?
 
Last edited:

razie

Sir Shiftsalot
Skier
Joined
Jan 18, 2016
Posts
925
Location
Ontario
I'm curious. @razie provided a link to determine how to arrive at BOF over CRS. In it it says:



Please define where on my foot where the BOF is. Is it the widest part? Is it where my 5th metatarsal meets the phalanges proximales? ???



Here is a definition I found:


I don't think I'm not going to feel that padded portion on the sole of my foot by tapping with a screwdriver handle.
Your foot is weirdly colored... :eek: but it's a very good point: where is the BOF... and yes, it's an approximation within say +/- 5mm or so...

Yes, where the 4-5th metatarsals meet the phalanges proximales is a good approximation. That's where I'd put most weight when lifting the heels.

For me, it took a lot of banging on the side around the first metatarsal (4) and on the sole around 4-5, then trying to line up my foot outside the boot with the different features of the boot (medial maleolus and the end of the first metatarsal) and then deciding on an average between the two...

It is a starting point... I generally use plates on all skis and use multiple sets of holes to be able to move the bindings back and forth until I like them. Many plate and binding combinations have positions like +1, 0, -1 which allow sliding the binding 1cm back and forth etc.
 
Last edited:

Noodler

Back in the game! :)
Skier
Joined
Oct 4, 2017
Posts
1,827
Location
Denver, CO
Why not? When you determine the CRS you're using the contact points, so looking at just the cambered portion, which is a good approximation of how the ski will feel. Of course, different rocker profiles will engage differently in soft snow and it also depends how you ski it - higher angles engage more of the ski, so it's not an exact science - it's just a starting point... but you bring a good point: type of ski and where you ski it influences the decision... how?
BoF over CRS was ALWAYS done by de-cambering the ski. When you de-camber any ski with some degree of early rise or rocker, the contact points will pull back to points that are "oddly" positioned to use the BoF over CRS position. I've done this lots and lots over the years with many of the modern ski designs. How many rockered skis do you actually own @razie ? ;)
 

Noodler

Back in the game! :)
Skier
Joined
Oct 4, 2017
Posts
1,827
Location
Denver, CO
I'm curious. @razie provided a link to determine how to arrive at BOF over CRS. In it it says:



Please define where on my foot where the BOF is. Is it the widest part? Is it where my 5th metatarsal meets the phalanges proximales? ???



Here is a definition I found:


I don't think I'm not going to feel that padded portion on the sole of my foot by tapping with a screwdriver handle.
These are the times when I really lament the loss of all that EpicSki content. I posted this info many times on Epic, but I guess it will need reposting now on PugSki.

The tried and true method I developed to find the exact point of your BoF is this:
  1. Grab a standard business card or other fairly thin card stock material.
  2. Stand on a hard floor surface with your bare feet.
  3. Stand up on you tip-toes so that the rear of your foot is fully elevated.
  4. Slide the business card in from the rear along the floor until it just contacts the ball of your foot where it's touching the floor. It's important to keep the card's long edge perpendicular to the long center axis of your foot.
  5. Put your foot back down onto the floor slowly so that you do not shift the card.
  6. Where the card was touching your foot when lifted is the point you want to mark on your foot. This is the precise position of the BoF that we use for ski binding mount location determination.
What I typically would do from this is then also mark the midpoint of my foot and then measure the distance from the BoF mark to the midpoint mark on my foot. This is the "BoF to midpoint" adjustment measurement.

If you have a great shell fit in your boots, you don't need to tap the boot to figure out where your BoF lands. A tight boot should land your midfoot position darn close to the boot's midsole mark. So all that's needed is to measure along the boot from the midsole mark to the BoF point in the boot by using your measurement of the BoF-to-MP adjustment.

Now you can take that BoF position marked on the boot and mount the bindings to CRS point on the ski. That is, IF it's a ski without any rocker/rise. ;)
 

razie

Sir Shiftsalot
Skier
Joined
Jan 18, 2016
Posts
925
Location
Ontario
BoF over CRS was ALWAYS done by de-cambering the ski. When you de-camber any ski with some degree of early rise or rocker, the contact points will pull back to points that are "oddly" positioned to use the BoF over CRS position. I've done this lots and lots over the years with many of the modern ski designs. How many rockered skis do you actually own @razie ? ;)
I think I own at least 1 or maybe 2 :roflmao: but all my skis have tips and tails that point up !!!

Why would you decamber the ski to find the crs? Here's a simple process similar with what I would use - see link below (this or just put them on the floor and mark the contact points) - so it depends how "firmly" you hold the skis, I guess - too firmly you'd decamber them:

Step 1: Find the running surface.

  • Hold skis firmly together, base to base.
  • Slide the card down between the tips until it stops. Keep the bottom edge of the card horizontal or you will get inconsistent results.
  • Mark the sidewall of the ski there.
  • Slide the card up between the tails until it stops.
  • Mark the sidewall there.
  • I recommend repeating this for both edges of the ski, and measuring several times until you get a consistent, repeatable result.
http://www.gnolls.org/756/howto-mount-alpine-skis-using-the-ball-of-foot-at-center-of-running-surface-method/

If you de-camber the ski when measuring the CRS, it don't think it says anything about how it skis at different angles and different types of snow... although it may give an indication of how it flexes... I don't think you'd get an accurate running surface indication: how much would you decamber? What are the support points for tips and tail that you'd be decambering against etc...

so, in my mind:
1. decamber to measure CRS gives no indication of how it skis in soft OR hard snow
2. measure cambered section (touch points) gives a rough indication of where/how it skis on hard snow
3. the rockers muddy the waters, the more the rocker, the more muddy

I guess it would be interesting to do some experiments on a few skis and see how different the CRS comes out when decambering vs not decambering...

cheers
 
Last edited:

NE1

Putting on skis
Skier
Joined
Aug 22, 2016
Posts
115
Location
Central Mass
Why would you decamber the ski to find the crs? .....
If you de-camber the ski when measuring the CRS, it don't think it says anything about how it skis at different angles and different types of snow... although it may give an indication of how it flexes... I don't think you'd get an accurate running surface indication: how much would you decamber? What are the support points for tips and tail that you'd be decambering against etc...
I think he means to decamber them against a perfectly flat surface, and/or with the skis base to base as you suggest, I believe, not as if over-flexing in a shop.
 

Noodler

Back in the game! :)
Skier
Joined
Oct 4, 2017
Posts
1,827
Location
Denver, CO
I think I own at least 1 or maybe 2 :roflmao: but all my skis have tips and tails that point up !!!

Why would you decamber the ski to find the crs? Here's a simple process similar with what I would use - see link below (this or just put them on the floor and mark the contact points) - so it depends how "firmly" you hold the skis, I guess - too firmly you'd decamber them:

Step 1: Find the running surface.

  • Hold skis firmly together, base to base.
  • Slide the card down between the tips until it stops. Keep the bottom edge of the card horizontal or you will get inconsistent results.
  • Mark the sidewall of the ski there.
  • Slide the card up between the tails until it stops.
  • Mark the sidewall there.
  • I recommend repeating this for both edges of the ski, and measuring several times until you get a consistent, repeatable result.
http://www.gnolls.org/756/howto-mount-alpine-skis-using-the-ball-of-foot-at-center-of-running-surface-method/

If you de-camber the ski when measuring the CRS, it don't think it says anything about how it skis at different angles and different types of snow... although it may give an indication of how it flexes... I don't think you'd get an accurate running surface indication: how much would you decamber? What are the support points for tips and tail that you'd be decambering against etc...

so, in my mind:
1. decamber to measure CRS gives no indication of how it skis in soft OR hard snow
2. measure cambered section (touch points) gives a rough indication of where/how it skis on hard snow
3. the rockers muddy the waters, the more the rocker, the more muddy

I guess it would be interesting to do some experiments on a few skis and see how different the CRS comes out when decambering vs not decambering...

cheers
Too bad you weren't around years ago during the EpicSki era when we debated this stuff for entire ski seasons. :roflmao:

You posted the answer yourself in that process. "Hold skis firmly together, base to base" That means that the skis are fully de-cambered. That's really the only way to do it with a high degree of accuracy. If you don't de-camber it fully flat, then there's no telling exactly what you'll end up with as skis vary a bit in the amount of camber they posses. Also consider that the measurement methods used would also bring into play unwanted variables due to how much unintentional force (whether from gravity or other means) may create inconsistency in the measurements. It's always been part of the process to measure the contact points when fully de-cambered.

I've been doing this binding mounting position stuff for over 15 years now. Those who have been around a long time (back into the early EpicSki years), know I have a bit of a "reputation" when it comes to binding mount position and the methodology involved. I made a thread there called "Binding Mount Position for the 21st Century" (which is referenced in this TGR thread and discussed there). Too bad that it's now long gone, but in summary I had developed a method that moves beyond BoF over CRS to what I called BoF over CEE (Center of Effective Edge). The basic idea is that instead of using the running surface length, you find the Effective Edge length and use the center of that instead for modern shape skis. It yielded much better results for me and others for many years. However, recently (and based on discussions with HH), I moved away from using that and entirely to allowing the ski design to mostly dictate my mount position by placing the boot shell midsole directly aligned with the narrowest point of the ski sidecut. That has been working the best for me with all types of skis. YMMV :)

BTW - I learned the hard way (many times) that BoF over CRS does NOT work with modern skis with more complex geometries and rocker profiles. You can trust me that it doesn't work or learn the hard way too. ;)
 

Noodler

Back in the game! :)
Skier
Joined
Oct 4, 2017
Posts
1,827
Location
Denver, CO
Here's an interesting read on the binding mount position from a long defunct message board where I used to participate. This was quite "late in the game" for me, after my thoughts on the subject had reached full evolution through many years of experimentation.

Note that this board had "died" and was brought back to life in a migration that made all the posts look like they were coming from the same author. The imported posts within the thread do provide indication of who actually posted the original message.
 

crgildart

Gravity Slave
Skier
Joined
Nov 12, 2015
Posts
7,123
Location
The Bull City
If you're measuring. might want to go by running surface end to end, especially if the skis have turned up tails or rocker. If only rockered one side all bets are off. And. there's no guarantee that they were mounted correctly to start with so using the old mount point might actually be worse than eyeballing it and just making sure both are done the same place.
 

Uncle-A

In the words of Paul Simon "You can call me Al"
Skier
Joined
Dec 22, 2015
Posts
3,091
Location
NJ
Why not post a close up photo of the binding it may help those who have worked on bindings before.
 

Staff online

  • Dwight
    Practitioner of skiing, solid and liquid
  • Andy Mink
    I am a half fast skier.
  • dbostedo
    Asst. Gathermeister-- Jackson Hole 2020
Top