OB4: Please help with tension data

[Than_Bogan]

I am working with OB4 to see if we can establish a simpler method of accurately setting the tension screw. To aid that effort, I am asking for every OB4 user to respond to this thread with the following:

 

The letter setting you believe you are using.

Your weight in pounds.

A caliper measurement of how much each tension screw extends beyond the housing. (Round to hundredths or leave that to me.)

Any comments about your skiiing style or how sure you are that your tension setting is ideal for you.

 

I'll start:

 

K

170

0.37" front and rear

I'm a shortline guy but not especially aggressive. I was very confident in my settings last season but have had some trouble getting back to the right spot this year, which is part of why I'm working on this!

[ALPJr]

@Than_Bogan hopefully I'll be able to gain some insight from you and other OB4 skiers. I hope to have a package coming my way soon.

[Than_Bogan]

@jdk99 @JJVDMZN @BlueSki @Deanoski @desmonipoux

 

Anybody? :smile: I really think this could be enormously helpful, but I need to get some data!

[jdk99]

@Than …didn't have my calipers with me last few sets. WIll get you my data this week.

[BlueSki]

Same here. Should have a chance over the next week.

[MattP]

.275 155lbs -35@36mph. Front system only. I am not usually still on my ski through the exit of the turn.

[Deanoski]

Than you are over thinking this!!! every spring is different the only way to make sure your tension is correct is to do a dry land release test just like you would do for a reflex system.

 

I test my front in a OTF then test the rear Out the back

my rear spring tention is set lower than my front binding.

 

 

 

 

[Than_Bogan]

@Deanoski I disagree on all counts. But perhaps you can convince me. How can you tell that the setting is correct based on such a test? I've attempted that and can barely feel the difference between dramatically different release settings. And Mike Mosley has told me he doesn't use manual release as a metric at all, and may not even be able to release from his that way.

[gginco]

I just ordered this system and expect it to arrive this week. This thread isn't giving me any warm and fuzzies that I should trust it. Is this system still in heavy R&D stage?

[Than_Bogan]

@gginco No I wouldn't say that. @mmosley899 has been using it for years. This discussion is more like fin settings for a ski.

[MattP]

I'm kinda with @Deanoski I would say my spring has undergone a lot of use and that my cam has been replaced a few times. I think there are a lot of variables involved when setting release tension with OB4 and with other systems. What works or one skier might not work for another. Does @Than_Bogan think too much into stuff? you betcha. Is it usually for a good reason? Sure. It's a lot like sharing fin settings between people and different calipers. It gets you close but at the end of the day it is what works best for you and your style.

 

@gginco defiantly not in R&D. Tested for a long time.

[Than_Bogan]

Well said @MattP, although I am still optimistic that this measurement will be "fairly comparable" from system to system.

 

Btw, a big part of my personal problem is that I am complete novice at setting a release tension period. I've been in rubber for decades, and I never became expert enough with snow skis to do anything but accept whatever the shop did.

 

And I absolutely did outsmart myself when I first got these, but my goal with this current effort is actually to simplify for everyone. Overthinkers need simple instructions even more than idiots do!

[mmosley899]

The springs we use are very precision built to specific specifications. Than is researching whether we can use these measurements as a way to determine settings. I use a torque wrench to determine settings for each system built. The setting that each skier uses is dependent on a variety of factors and can be adjusted according to our chart and skier input. I have used the same springs in my releases for years with no deterioration of pressure.

[JJVDMZN]

Will send my info @Than_Bogan

 

[JJVDMZN]

@Than_Bogan , @mmosley899

If you want more accurate adjustments, I suggest that the adjustment screw must be flanged / locked at the lowest setting (H) so that it cannot screw in deeper and the using shims to set the other 7settings (I-O).

This way the adjustment screw cannot unscrew and change the tension.

[JJVDMZN]

JJ: Male

Letter: K

Weight: 171lbs, 5'11"

Front: 0.324, Rear: 0.348

Not aggressive, still learning at 46km/h (28mph)

 

Aidan: Male

Letter: L

Weight: 163lbs, 6'1"

Front: 0.301, Rear: 0.307

Aggressive at 58km/h (36mph)

 

Monica: Female

Letter: H-I

Weight: 158lbs, 5'11"

Front: 0.409, Rear: RTP

Not aggressive, still learning at 46km/h (28mph), she wants the boot to release easily.

[Than_Bogan]

Great info!! Am I correct that was the setting Aidan was on in that epic crash video where they released perfectly?

He has the same build I do, so that's a great data point for me personally.

Finally, have any of those been double checked with a torque wrench or just relative to where it came (K)?

[JJVDMZN]

Yes that's correct @Than_Bogan

I do not have a torque wrench, Aidan just wanted a higher setting, so I turned it in 1/2 a turn, when I turn it back 1/2 turn I get 0.340, the same as my rear setting

[jdk99]

@Than. Current settings:

 

185lbs

 

.75 turn cw from factory both front and rear. Presumed L/M (60 ft/lbs). Torque not tested.

 

Front: 0.262

Back: 0:292

 

Again, I'm either type b or c so still a little conservative

 

NB. The factory mark on the rear doesn't quite line up cleanly w the mark on the housing so not sure it's accurate. Might explain length discrepancy

 

[Bookm_dano]

Hey @Than_Bogan ...finally got a chance to measure my tension screws today:

180 Lbs

30 mph novice

32 to 34 mph open water

Front - .361

Rear - .359

Could go a bit tighter but still shy from an ankle injury last year (which inspired me to buy the OB4s).

[BlueSki]

Finally got this done.

178 lbs

L on the OB4 chart

.33 rear and .38 front

 

Not sure why the difference is so great, I checked the marks from where Mike set if for me at 56 lbs when he changed the cams last year. The back had actually crept out a bit but I tightened it up before this measurement. Average intensity skier, deep 32 off.

 

[JJVDMZN]

Had an OTF with the ski twisting at 52km/h, both boots released but felt a slight pain in my left ankle (which didn't last long) from the ski's twist.

 

To be safe I'm turning the tension screw out a 1/4 turn on the front (left) foot, this should put it closer to the rear setting of 0.348.

 

My old settings

JJ: Male

Letter: K

Weight: 171lbs, 5'11"

Front: 0.324, Rear: 0.348

Not aggressive, still learning at 46km/h (28mph)

 

New Front: 0.340

 

 

[ccogan]

Just got my new OB4 System in the mail this week, so I can’t claim that I have any setup locked in at this point relative to what tension data is correct for my height, body weight, riding style (5’-10”, 165lbs, aggressive and mostly open water skier – 32mph). That said, just finished calibrating the tension springs with torque wrench and dry land release tests. You can see in the attached pictures that to calibrate the tension release, we bolted up a steel plate for testing to avoid any damage to the aluminum binding plates. Then welded a bolt to the plate to apply force with a torque wrench. Tried to position our testing point similar to what Mike Mosley demonstrates on the OB4 website.

 

Found that the system as mailed to me was setup significantly tighter than setting K. The tension screw was screwed in almost completely and tested with our setup at +80 ft-lbs of torque to release. With some testing we found that 55 ft-lbs of tension correspond to approximately ~.21” of exposed tension screw (measured from the spring housing to the lip closest to the spring housing). You can see my crude measuring in the attached pictures, I will update when I have something more accurate to verify with.

 

A note about comparing “calibrated release forces”. Unless I’m thinking about this wrong I believe that the point of the force application on the plate will have a dramatic effect on the measured tension setting (apply a rotational force as we did with a torque wrench, applying the force closer to the spring = higher tension release readings. Vice versa, apply the force closer to the pivot point/wedge = lower tension release readings).

 

I’ll try to update when I’ve got more experience with finding the correct tension settings for me.

 

[gregy]

Good idea. Need to get a measurement from OB4 for attachment point on plate or you will not get the same readings. Also one on the concern I had was that the curve of the ski will cause a increase in spring compression. Test needs to be with plate on ski.

[Than_Bogan]

That tension screw in the second picture is extremely loose (unless something is fundamentally different about your setup vs. mine). I would definitely not ski with it that loose!

[Than_Bogan]

You appear to be measuring the same thing I suggested, but that should measure between 0.5" and 0.7". At 165 lbs that would be prerelease city. I don't know why your torque measurement isn't the same as Mike's, but I very seriously recommend against skiing with it at that position until you have figured out what is going on. Somewhere around 0.35" should be right for you.

[ccogan]

@Than_Bogan I'm confused by your last post. Are we measuring from/to the same points? Currently both screws on my setup measure ~.21" from the back of the spring housing to the first edge of the groove in the tension screw. BTW I haven't visited PreRelease City yet (it doesn't sound like a nice place), but i also haven't skied on it due to the 20 mph breeze here today.

 

Side note - Are others dry land testing the release? With your current setups can you/how easily pull free from the ski?

[Than_Bogan]

The measurement I intend (and that i believe everyone in this thread is using), is from the base of the housing to the TOP of the screw.

 

I am glad you saw my post.

 

Now that i have fixed my setting (with help from this thread!), I can JUST BARELY force a shore release if I put almost my entire body weight against it. Since you are not doing shortline slalom (yet!), you could be a little looser. But the setting in your picture is waay too loose.

[mmosley899]

@ccogan I agree with @Than_Bogan the screw is too far out. I cannot verify that your test is the same as what we have done in our settings during build. I think that we need to develop a standard testing procedure for everyone to do their own testing, that is what this thread is about. I have never used a shore release by standing on the ski and trying to release/pull out the boot as a test of the system. Than's measurement is from the end of the screw to the housing. Mine is currently at .340 on front and .360 on rear. Somewhere between .350 and .375 should work for most skiers. You should just be able to see the first indicator ring out side of the housing as in my photo. There are two other indicator rings that can be viewed through the site window. You can see that the second ring is just visible in the window, and there is also a tiny puch mark indicating the position where we tested the tension.

 

[ccogan]

Thanks @mmosley899 and @Than_Bogan for the quick advice, I will definitely be adjusting before the morning. I am a little puzzled at the moment over the difference in testing results. After drawing up a quick force diagram of the situation I no longer believe that the torque wrench application point should alter the release tension.

[gregy]

@ccogan after I got to thinking about I not sure myself. Try flipping you adapter plate around see what it does to you reading.

[Than_Bogan]

THANKS EVERYONE!

 

I've gathered enough data to make a probably-useful first pass. This can be found in my "guide" under "Setting the Release." Please read the whole section (as opposed to just looking at the chart).

 

https://docs.google.com/document/d/1M3z1wtYSyhHVQGdpaH_UOD2dEW0jhYlMHtD0eoizspg

 

 

[Than_Bogan]

I've also taken my own recommendation, and my own data is now:

 

M

170

0.302" front and 0.305" rear

There's a slight chance I'll loosen (increase) these a little someday, but the famous Aidan Crash Video, at almost exactly these settings, strongly suggests it will release as desired. And I believe I'm firmly out of prerelease territory now.

 

Aside: If only I had actually listened to @mmosley899 in the first place! I recently found a part of an email chain from 2014 where he explicitly warned me that what I was doing (going all the way to "J") could lead to a prerelease. GAWD I AM STUPID. But at least I am capable of learning...

[JayG80]

Thanks @Than_Bogan here are my wife's settings.

J setting

122 lbs , 5.5 ft

0.35" front and rear

W5 skier coming back from Rotator and Bicep surgery. Ski 15/22/28 at 32 mph. Will return to 34 mph as she builds strength and confidence. Not especially aggressive, type B.

 

No releases yet.

 

65" HO A2 with EXO boots on OB4 double boot plate.

 

Mike set her release at 45 ft#. He started at 50 ft# and set it back a 1/2 turn. Based on the chart, we may increase it to .375".

[JayG80]

Update, First release on OB4 setup. At 2 ball (offside) and 28' off, it was a decent fall and I saw the whole ski in the air. My wife's OB4s still had the J setting. Front boot released and the rear did not. One in, one out is bad. Think I will decrease the back boot tension. No injury.

[Than_Bogan]

@JayG80 No injury is most important! And thanks for continuing to share your data.

 

Did you already go to 0.375" as you hinted you might, or did this release occur at 0.35"? IF the information I've gathered is to be believed (which is still a huge if), then 0.35" is actually between K and L, which does seem a bit tight for somebody at 122 lbs.

 

To my way of thinking, 1-in/1-out is not a problem unto itself -- we're just trained to think it is because with almost any other system, it's dangerous because the ski is now a large lever arm acting in ways that most systems can't release. But the OB4 system CAN.

 

I would consider it a huge problem if the other one should have released, but didn't. But if there's never any significant torque acting on that foot, then a release is not required.

 

Full disclosure: I have theorized a few ways that the "other" foot could be automatically released whenever one is. I haven't been able to prototype anything yet, but technology always evolves and everything can be made incrementally better.

[JayG80]

Still at .35

 

Since the front released Ok, I am leaving the front tension at .35 and turning the rear release 1/2 turn ccw.

 

While, we are at it. For those in double ob4 and not using dual loc mounting like Than. Are you using screws in every location on the base plate? Seems like I can leave a couple out on the front boot around mid point.

[Than_Bogan]

@JayG80 Makes sense to me. There may even be a general justification to having the front one a little tighter than the rear one, since a pre-release from the rear is nearly impossible, which moves the center point that lies between "dangerously loose" and "dangerously tight."

 

Obviously, I can't directly answer your mounting question, but I can say that my Dual Lock results make it pretty obvious that a lot of force is concentrated near the three plate-connection points (housing, middle piece, housing), and therefore I strongly suspect that only a few screws are needed anywhere else.

[Greg Lukin]

Better late than never - After a pre-release I have now screwed in the spring a half turn.

 

think/hope I'm on setting M

Weight - 230 but coming down - aiming for 210 in 6 weeks or so

22 off skiing at 34 atm

0.2755 - front binding only

 

I'm hoping as I lose weight my skiing will progress and hence will be able to stay on the same setting.

 

 

 

 

[BlueSki]

@JayG80, I am only using 6 screws plus the the 3M auto trim tape under the housings. In conversation with Seth Stisher about the system he suggested using only six to better allow the ski to flex vs using a screw in every available spot.

[Than_Bogan]

Greg -- that's awesome. I've been hoping for some data from somebody over 200. It seems like my linear assumptions are roughly on target for your size. Just to be absolutely sure, the 0.28ish number is where you moved to, not where you pre-released, correct?

 

Meanwhile, as I suggested that I might back on 7/18, I've gone a little looser, with both screws now at 0.34". This was precipitated because yesterday I actually had two "interesting" falls, so I got some useful data out of that. The first fall was a ski-stop situation, what some call "stuffing the tip." Even at 0.30" I ejected immediately with no trauma. TOTAL WIN! But in the second one I lost it at full speed right off the ball, and bounced, spun, and twisted into the wakes. I did not release in this one, and while the result was at most a "minor tweak" (I could ski again today), I think I generally do want it to release in that situation. And I'm still very far from the 0.41" region where I pre-released.

 

So while I think at 0.30" I was safer than I'd be on any other system, my guess is I will be even safer at 0.34".

 

P.S. I'll be at the Nationals site all day tomorrow (Friday), most likely wearing my blue floppy "Nationals 2000" hat. Feel free to come say hi!

[thager]

@Than_Bogan Not to throw a monkey wrench in this but are you assuming that all springs are the same nonloaded tension? There's a reason the snow ski industry uses standardized measuring equipment for release.

[Than_Bogan]

@thager I wouldn't call that a monkey wrench -- that's more like a fundamental question! My chart has no choice but to assume that, but I personally do not. At least not yet. I have some reasons to believe that the OB4 springs are very consistent, but that is not yet proven.

 

One goal of this thread is to try to figure out if sharing extent measurement has value. So far I think it does, but there may be tuning required by individuals thereafter.

 

But also, I strongly believe that these springs will maintain their tension characteristics for many years, and so even if the extent method doesn't perfectly translate from system to system, it's at least a good way of measuring your own system reliably and consistently.

[Greg Lukin]

@Than_Bogan - yes thats correct...

 

[JayG80]

@Than_Bogan Update to my Aug 12 post on this thread. Offside 2 ball 22/32, in choppy water. Bad fall with no release or injury. Front foot half way out of hardshell EXO boot. Moved tension spring cap from .375 to .390.