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Do I understand BOF?

post #1 of 16
Thread Starter 
Just kinda curious, 'cause I see some phrases being tossed around that don't make sense to me.

I see some phrases where people talk about things like mounting the bindings at "at +2cm which is 0.5 behind BOF" (just one example I found in a thread, but I've seen this kind of language before).

What does that mean? What's is actually "behind" the BOF in that case? Is the implication that the CRS (center of running surface) is .5cm behind the BOF? I just get confused when people talk about mounting in front of or behind the BOF... since BOF isn't on the ski, you move the mount and the BOF moves.

Here's what I understand:
You can either use the midsole boot mark and align that with the mark on the skis, and then go forward or backward from there, but the boot midsole and the mark(s) on the ski is the reference point.

or

You can use the BOF method, and align the BOF with the CRS, and completely ignore the boot sole/ski marking for the purpose of finding the right spot.

However, when people talk about mounting a binding 2cm back (say for a twin tip being used for all-mountain), I assume that's a reference to the boot sole mark and the ski mark? Normally not talking about mounting the binding so that BOF is 2cm behind the CRS, unless explicitly stated, correct?

Do I understand this, and people are just using confusing terminology, or do I have no clue what I'm talking about? Thanks!
post #2 of 16
Quote:
Originally Posted by jaobrien6 View Post

You can use the BOF method, and align the BOF with the CRS, and completely ignore the boot sole/ski marking for the purpose of finding the right spot.

However, when people talk about mounting a binding 2cm back (say for a twin tip being used for all-mountain), I assume that's a reference to the boot sole mark and the ski mark? Normally not talking about mounting the binding so that BOF is 2cm behind the CRS, unless explicitly stated, correct?
That is how I understand the descriptions on this forum as well.
post #3 of 16
Quote:
Originally Posted by jaobrien6 View Post
Just kinda curious, 'cause I see some phrases being tossed around that don't make sense to me.

I see some phrases where people talk about things like mounting the bindings at "at +2cm which is 0.5 behind BOF" (just one example I found in a thread, but I've seen this kind of language before).
That's easy, mounting the binding so the boot center lines up at 2 cm in front of the manufacturers mark, which measures out to .5 cm behind where it would have mounted using ball of foot to CRS method.


Quote:
Here's what I understand:
You can either use the midsole boot mark and align that with the mark on the skis, and then go forward or backward from there, but the boot midsole and the mark(s) on the ski is the reference point.

or

You can use the BOF method, and align the BOF with the CRS, and completely ignore the boot sole/ski marking for the purpose of finding the right spot.
Yes, or you can compare where the two methods puts your foot, and if they're not the same spot, choose one of the two, or go for something in between. Which is what they were doing in your example.

Quote:
Do I understand this, and people are just using confusing terminology, or do I have no clue what I'm talking about? Thanks!
Yes, no, yes.

BTW, I always advocated using the manufacturers mark, until I mounted a pair of twintips that had only one mark, and found it was only marked for rail, (some twintips have three marks for rail-park-all mountain), The ski tails washed out and they were quick turning but not stable through the turn. I mounted them to BOF, which put them -4 (4 cm behind the mark), and love them now.
post #4 of 16
Thread Starter 
Quote:
Originally Posted by 2-turn View Post
That's easy, mounting the binding so the boot center lines up at 2 cm in front of the manufacturers mark, which measures out to .5 cm behind where it would have mounted using ball of foot to CRS method.
Perfect. Thanks!!
post #5 of 16
by the way. Regarding recommendations to mount at manufacturer recommended spot. Remember it is simply a spot picked by a group of ski testers and has no relation to what you may like.
post #6 of 16
Quote:
Originally Posted by race510 View Post
by the way. Regarding recommendations to mount at manufacturer recommended spot. Remember it is simply a spot picked by a group of ski testers and has no relation to what you may like.
Gee, and to think some people think a bunch of ski designers would know better than the general public.:
post #7 of 16
Ski testers, ski designers. Gee I wonder if there is any difference. Unlikely despite different titles, huh. Some people just like to use extra words. I wonder if they all agree. Probably, they all have the same title after all. Probably could get just as good a result if they only used one tester.
post #8 of 16
Quote:
Originally Posted by 2-turn View Post
Gee, and to think some people think a bunch of ski designers would know better than the general public.:
The main issue is that they use a midsole mark, and this located for an "average" boot sole length (whatever that may be). For boot sizes that differ dramatically from this average, the mark won't be right.

I have an older pair of Olins in the garage, and they actually have a range of midsole marks for different boot sole lengths. This is a great way to do it, as opposed to one average mark. The only remaining variable is where the BOF lies in relation to the midsole mark and the ski sidecut center -- there is still an assumption there.
post #9 of 16
Quote:
Originally Posted by skier219 View Post
The main issue is that they use a midsole mark, and this located for an "average" boot sole length (whatever that may be). For boot sizes that differ dramatically from this average, the mark won't be right.

I have an older pair of Olins in the garage, and they actually have a range of midsole marks for different boot sole lengths. This is a great way to do it, as opposed to one average mark. The only remaining variable is where the BOF lies in relation to the midsole mark and the ski sidecut center -- there is still an assumption there.
Actually, before that, Olin just had a mark for the toe(as did Volkl and others), then went to the scale that you mention (which worked out the same). I always thought the toe mark would have been more accurate and wondered why they all adopted to the mid-sole.
post #10 of 16
The toe mark is no more accurate, just different. It has never been a goal in mounting to get the boot toe in any particular position, although we used to use it (toe of boot/mid chord length) as a quick way to approximate BOF/CRS. It is more accurate than what we do now, but still an approximation of the accepted BOF/CRS.

What we do now is complete rubbish and doesn't serve anyone accept ski techs who now have a faster way to mount. And the ski companies that now have consistency in the way their skis are mounted. Of course those are good things, but they don't help us get skis that work as well as possible for us.
post #11 of 16
race510, well put -- I agree completely! It would be nice if the boot manufacturers made an attempt to mark the BOF location on the boot shell (they could probably get within 1 cm of the true BOF on the "foot" since there is only so much variability there for a correct boot/foot fit) and have the ski makers mark CRS. That would likely be better than the trial&error involved when I try to determine BOF and CRS.
post #12 of 16
Quote:
Originally Posted by skier219 View Post
The main issue is that they use a midsole mark, and this located for an "average" boot sole length (whatever that may be).
Usually a 27 shell from the manufacturer.
post #13 of 16
27 is a typical guys size, but 26 is probably average. Either way, not certain that it matters what the average boot sole length is when it comes to where the midsole mark is.

Mark is consistently placed with respect to running surface on all length skis in a given model.
post #14 of 16
Quote:
Originally Posted by race510 View Post
27 is a typical guys size, but 26 is probably average. Either way, not certain that it matters what the average boot sole length is when it comes to where the midsole mark is.

Mark is consistently placed with respect to running surface on all length skis in a given model.
I was mounting my own skis that only had a rail mark, so I asked the owner where I should mount them, and he didn't hesitate when he said, IIRC, "mark it xxcm behind the CRS." considering he was a ski rep, a pedorthist 30 years in the industry and has a mind like a steel trap, I'm betting that must be the industry standard for mid-sole marks. 2xx is probably the distance from average midsole to average ball of foot. Next time I see him, I'll ask again.
post #15 of 16
FWIW, though for teles, this is a good description of locating BOF & CRS from Telemarktips.com.
post #16 of 16

mid-sole mark

2-turn
Something is clearly lost in translation. "There is no standard for location of mid-sole mark." This from discussions with chief of design for Atomic, Stockli, Goode, Vist and others. You can also prove it to yourself by simply reaching into your quiver and measuring some different skis with respect to location of mid-sole mark vs CRS.

Once more "There is no standard" The position is determined by ski testing skis once they are designed.
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