Binding mounting point

Discussion in 'Tuning Techniques and Tool Information' started by Skisix, Oct 6, 2019.

  1. Skisix

    Skisix Booting up Skier

    Joined:
    Dec 1, 2018
    Posts:
    21
    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?
     
  2. cantunamunch

    cantunamunch Meh Skier

    Joined:
    Nov 17, 2015
    Posts:
    7,514
    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.
     
  3. Thread Starter
    TS
    Skisix

    Skisix Booting up Skier

    Joined:
    Dec 1, 2018
    Posts:
    21
    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...
     
  4. cantunamunch

    cantunamunch Meh Skier

    Joined:
    Nov 17, 2015
    Posts:
    7,514
    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.
     
  5. Thread Starter
    TS
    Skisix

    Skisix Booting up Skier

    Joined:
    Dec 1, 2018
    Posts:
    21
    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!
     


  6. Noodler

    Noodler My win/win/win for 2020: Ikon/LL/A-Basin Skier

    Joined:
    Oct 4, 2017
    Posts:
    1,060
    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.
     
  7. razie

    razie Sir Shiftsalot Skier

    Joined:
    Jan 18, 2016
    Posts:
    788
    Location:
    Ontario
    BOF over CRS, that's the basic principle for mounting bindings. There's a bunch of details here.
     
    Last edited: Oct 9, 2019
    rocdoc and Jacques like this.
  8. Noodler

    Noodler My win/win/win for 2020: Ikon/LL/A-Basin Skier

    Joined:
    Oct 4, 2017
    Posts:
    1,060
    Location:
    Denver, CO
    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.
     
  9. Doug Briggs

    Doug Briggs Skiing the powder Industry Insider Pugski Ski Tester

    Joined:
    Nov 9, 2015
    Posts:
    3,722
    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.
     
  10. Doug Briggs

    Doug Briggs Skiing the powder Industry Insider Pugski Ski Tester

    Joined:
    Nov 9, 2015
    Posts:
    3,722
    Location:
    Breckenridge, 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? ???

    [​IMG]

    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.
     
  11. razie

    razie Sir Shiftsalot Skier

    Joined:
    Jan 18, 2016
    Posts:
    788
    Location:
    Ontario
    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: Oct 10, 2019 at 6:11 AM
    Jacques likes this.
  12. razie

    razie Sir Shiftsalot Skier

    Joined:
    Jan 18, 2016
    Posts:
    788
    Location:
    Ontario
    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: Oct 10, 2019 at 6:03 AM
    Jacques likes this.
  13. Noodler

    Noodler My win/win/win for 2020: Ikon/LL/A-Basin Skier

    Joined:
    Oct 4, 2017
    Posts:
    1,060
    Location:
    Denver, CO
    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 ? ;)
     
  14. Noodler

    Noodler My win/win/win for 2020: Ikon/LL/A-Basin Skier

    Joined:
    Oct 4, 2017
    Posts:
    1,060
    Location:
    Denver, CO
    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. ;)
     
    Jacques and LiquidFeet like this.
  15. razie

    razie Sir Shiftsalot Skier

    Joined:
    Jan 18, 2016
    Posts:
    788
    Location:
    Ontario
    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-mou...-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: Oct 10, 2019 at 12:56 PM
    Jacques likes this.
  16. NE1

    NE1 Putting on skis Skier

    Joined:
    Aug 22, 2016
    Posts:
    85
    Location:
    Central Mass
    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.
     
  17. Noodler

    Noodler My win/win/win for 2020: Ikon/LL/A-Basin Skier

    Joined:
    Oct 4, 2017
    Posts:
    1,060
    Location:
    Denver, CO
    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. ;)
     
    Jacques and LiquidFeet like this.
  18. Noodler

    Noodler My win/win/win for 2020: Ikon/LL/A-Basin Skier

    Joined:
    Oct 4, 2017
    Posts:
    1,060
    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.
     
    Jacques likes this.
  19. crgildart

    crgildart Gravity Slave Skier

    Joined:
    Nov 12, 2015
    Posts:
    6,289
    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.
     
  20. Uncle-A

    Uncle-A In the words of Paul Simon "You can call me Al" Skier

    Joined:
    Dec 22, 2015
    Posts:
    2,731
    Location:
    NJ
    Why not post a close up photo of the binding it may help those who have worked on bindings before.
     
    Doug Briggs likes this.

Share This Page


  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice