A Complete Idiots Guide to OB4 Systems Bindings

Than Bogan

August 2014: Created

September 2014: Improved information about release settings

July 2015: New release setting info

July 2015: Main guide now refers to OB4 shell.  Soft shell info moved to Appendix.

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A Quick Review

I believe the OB4 Systems release is the overall safest binding system that exists today.  No binding can prevent all waterski-related injury, but being able to release in every possible direction independently can prevent a wide variety of binding-related injuries.  And pretty much any hard or soft shell boot can be mounted to the system.

Yes, they are expensive.  When I asked myself “How much is a season worth?” they suddenly seemed a lot cheaper.

I don’t recommend the P80 soft shell, but I love the OB4 “low cuff” shell with the Intuition liners.  This gives me the perfect combination of comfort, ease of use, strong foot control, and the ability to leverage without rolling the ski over into an inefficient position.

However, the OB4 Systems binding is a bit of a bleeding edge product, and so if you pick up a set, your ski partner probably won’t be able to help you much with setup, etc.  I am hoping this totally unauthorized “manual” can help fill that gap.

This is sort of in chronological order, but I still suggest reading this whole thing before you start.

Take ‘em Apart

I highly recommend disassembling the plates from the boots, paying close attention to how they are set up.  When you put them back together, take the time to figure out where the degrees of freedom are in the setup.  The slots in the aluminum allow you to rotate the boot (or in theory move it left or right if you really want).  Fine adjustment front and back can be achieved with a slotted hole in the bottom of the boot -- see below.  As of this writing, you’ll have to do the slotting yourself.

If you wish to cant the boots (i.e. rotate them around the ski’s long axis), then you’ll need to insert some small wedges before you tighten up the bolts connecting the boot and plate.  I have not done this, but I suspect the “usual” method of inserting dimes can get you where you want.  The rule of thumb seems to be that the stiffer the shell you use, the more you need to cant them so that they sit in a natural position.  I have not found this necessary with the OB4 shells, perhaps because they have a lower cuff.

Drilling & Slotting

In my case, I asked OB4 to send me the shells “as is” and I set them up myself.  I drilled them with a 5/16” bit, making sure that the spacing between my holes matched that of the plates that I wanted to use.  I suggest that the front boot should be near the back of its plate, for two reasons: 1) Allows proper spacing (see below) without getting in the way of the release, 2) Helps get the right balance of force between releasing from the rear and the front.

Drilling the shell is straight-forward, but since I am uncoordinated and anal, I drilled small pilot holes first.  In this picture, the front hole has been drilled and the rear hole has only been piloted:

20150703_083134.jpg

I prefer to make a slotted hole to facilitate front-back movement.  This is especially useful on the rear boot to adjust the spacing; to move the front boot you could choose to move the entire plate system.  I slotted by using the simple method of drilling two pilot holes about ¼” apart, then drilling through each with the 5/16” bit, and then rattling it back and forth to clear it into a slot:20150703_095927.jpg

This is also an easy way to change a single hole into a slot: Make a pilot hole just beyond the hole and then drill it with the 5/16” bit.

Get the Spacing Right

Especially with a dual-boot setup, but really in all cases, it’s critical to get the space right between your front and rear ankles.  I can’t imagine any total beginner using OB4s, so that means you already have some binding system, with a spacing that works for you.  To be successful with your OB4s, you must get that same spacing.

The first aspect of that is positioning the boots relative to their plates.  Don’t forget that you can change the spacing by moving either the front or rear boot OR BOTH.  Some positions may be easier to set because of the spacing of the slots or other aspects,  so take advantage of being able to move “the other boot” if one of them doesn’t seem tight and stable in a given spot.

If using dual boot, you’ll almost certainly have to cut the toe off your rear boot to achieve the desired spacing.

Cut off the rear toe

Cutting the OB4 shell is very easy with a standard hacksaw.  If you happen to have one, a mini-hacksaw is a nice way to start with the track you want, and then switch to the regular hacksaw.  Of course, make sure you remove the liner AND any plastic pieces or anything else that is removable before you start the chopping.

You may also need to cut some sole insert or something – ordinary scissors should be able to handle that.

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If you have an odd-sized foot (as I do with an 11), one option is to use the smaller sized shell (10 in my case) and cut the toe off the FRONT boot as well.  With my foot being narrow, I think I would swim in the 12, but the 10 was pressing on my big toe, so I removed that part!  (I did that after the picture on the railing.)

Mount boots to plates

The hardware that comes with the OB4 shells is good, but I personally recommend inserting a ¾” diameter rubber washer, such that the “stack” is as follows:

Stainless T-nut

¼” or 5/16” rubber (aka neoprene) washer, ¾” diameter.  (Larger is OK but may curl up a little.)

(bottom of boot)

(OB4 plate)

stainless steel hex head bolt 20-thread ¼” diameter (length of bolt depends on shell details)

If you need any extra bolts, including of different lengths, I highly recommend BoltDepot.com.  (If you have older Phillips bolts, I recommend replacing them with hex-head bolts.)  Note that the “mushroom” head bolts actually work quite well on both the “new” style of plates (with a flat recessed slot on the plate) and the “old” style (with a beveled slot).

Then crank this down TIGHT.  Thanks to the rubber washer, it’s pretty easy to get everything to have enough friction that you can crank it down.  This combination should hold with no further maintenance (except maybe after a big crash).

ob4boots.jpg

When you’ve got them where you want relative to the plates, use a metallic Sharpie to place various pairs of marks on the boot and plate so that you can easily check if they are in the correct place.  At least one pair of marks in the front, back, and side are needed to lock down all of the degrees of freedom.  I suggest a technically-redundant pair of marks on both sides, since that can make it easier to find a mark you can see while tightening.

Any time you release, re-examine all the marks you made. The force of a release may cause something to move.  If so, loosen up the screws, reset the boot to the marks, and then crank ‘em down again.

Base Plate Installation

If you have a brand of ski with inserts that match both the main pattern and the extended area where the pins are, then this may be pretty trivial.  I would strongly consider a Mikro-Just or similar in this case, so that you have an easy way to lockdown the front-back position of the base plate.

Some manufacturers or pro shops are happy to add inserts for you.  That may be the easiest solution when practical.

Since I am on Goode, I ended up mounting the base plate using Dual-Lock.  I’m not absolutely sure this would hold well enough for a heavier skier, but at 165 lbs it seems to work great.  The ski side should be 250 black Dual-Lock and the plate side should be 400 Dual-Lock.  No other combination is strong enough – this is NOT optional!

The patterns I used can be seen in this picture:

HOWEVER, I made a mistake and you really want to use black Dual-Lock on both sides.  I discovered this the hard way (well at least I saw the adhesive peeling as opposed to a huge crash!), but found that the only critical place for it is the last 6” or so in the back.  The clear is more convenient  in many ways, especially when it comes time to replace it, but the clear adhesive is not strong enough to handle the fact that the forces are concentrated in just 3 places.

Also, don’t forget that Dual-Lock adhesive takes 72 hours to fully cure.  I wouldn’t even consider snapping the two sides together until 24 hours have passed, and be warned that if you release inside that 72 hour curing period, you will probably pull up some adhesive and have to start again.

Once it’s all set up, the Dual-Lock is a pretty nice way to go.

Boot Position Notes

The OB4 manual states that you should consider setting your plate back a little from where you had it with rubber boots.  However, the back of the OB4 shell relative to the ankle boot isn’t the same distance as a rubber binding.  I found these to exactly cancel each other out, and the most comfortable spot for me was where the measurement to the back of the boot remained the same.

I found with the hard shells that I prefered a little extra rotation of my back boot.  It was pretty obvious that I needed this because I could feel my heel pressing against the boot trying to get to that position.

 

Setting the Release

NOTE:  Do not set the tension screws too loose.  It’s tempting to think that going looser increases your safety by allowing you to release more easily, but any settable system can dangerously release at maximum speed if it is set too loose.  The correct setting may “seem” very tight -- you may or may not be able to release it manually on the platform.  Don’t make the mistake that I and several others made of thinking you know better and loosening it.

The release ships from the factory set at “K”, which corresponds to a specific force to release a plate.  Each half turn (180 degrees) of the screws on the pins moves you tighter or looser by one letter.  The chart on OB4’s web site is fairly accurate, but I am working on a simpler way to get to the right spot and be able to easily verify that you are at the correct spot.  This method uses a measurement of how much of the screw is visible beyond the housing.  It can be measured to better than 0.01” accuracy with a standard caliper, for example as follows:

bindingscrewmeasure.jpg

Keep a record of these measurements so that you can get back to the same spot reliably after any maintenance.

The setting “K” corresponds to about 0.38” on most systems.  If yours is significantly different, then you’ll have to offset my recommended measurements below accordingly.

To set the tension, I have developed a formula that is based on the official chart plus data that I have collected from users.  This is still evolving and is NOT officially endorsed by OB4.  However, I believe this can be used to get a very good starting point, and that most tournament skiers won’t need to move from this setting.  If you are never above 28 mph, you might go as far as a full turn looser, and if you are a crazed maniac who never lets go of anything (e.g. Brian Detrick) then you might go as far as a full turn tighter.

The formula is (370-weight)/650, where weight is in lbs and the result is in inches.  But if you don’t feel like using a calculator, here’s a table:

100

0.42"

110

0.40"

120

0.38"

130

0.37"

140

0.35"

150

0.34"

160

0.32"

170

0.31"

180

0.29"

190

0.28"

200

0.26"

210

0.25"

220

0.23"

230

0.22"

240

0.20"

250

0.18"

260

0.17"

270

0.15"

Please understand that there is a range of settings that will work fine.  You do NOT need to be within 0.01” of some magic setting to be safe.  But by being precise in the above table, it makes it very likely that that setting will be within the ideal range for you.

Secure the Tension Screw

I strongly suggest putting a little blue loctite onto the threads of the tension screw.  It’s easy enough to break that if you change your mind, but you can rest easy that it won’t back out on its own.  Otherwise all that flexing and vibrating can sometimes cause the screws (especially the front one) to move considerably.

Base Rubber Piece

The modern OB4 system uses a hard rubber gasket-like piece under each boot plate.  I suggest quickly sanding both sides.  This prevents the bottom side from sticking to the aluminum base at the bottom.  And on the top side, where it is glued to the boot plate, it provides a better surface for the adhesive to bond with.

E6000 is by far the best glue I’ve found to mount the rubber to the aluminum, but you must follow the direction very carefully -- it doesn’t work the same as most other adhesives.

Buckle Notes

You’ll most likely want the toe buckle fairly tight, the middle buckle snug, and the top buckle rather loose.  With OB4 shells, I haven’t noted much difference in performance with small changes in buckle settings, but I still find myself counting clicks on the toe and middle buckles to make sure they are the same each time.

Hopefully by the time you are reading this, the OB4 shells will ship with better buckles.  But in any case, if you want to replace buckles, AggressiveMall.com is the place to get them.  You can break any rivets with a drill bit that is a little bigger than the rivet hole, and then using a regular head screwdriver to force them off them:

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Getting Back in the Boat

One of the best tips I got directly from founder Mike Mosley is to use the levers in the front and back to release the tension and pop the boots off the ski when done with your set.  Dealing with buckles under the water is a little frustrating – and completely unnecessary!  Just pop ‘em off and deal with them in the boat.

My boot/plate combinations float, but only if the liner stays in, so pay a little attention when taking them off!

Liner Care

Always remove the liners and put them somewhere they can dry.  That seems to be pretty much all you need to do (even with the relatively cheap liners that come with the P80 rollerblade style boots).

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I did not do any special molding, but found that after a few sets the comfort increased slightly.

Do the Maintenance!

Make sure you follow the maintenance guidelines for the pins, notably hitting them with WD40 after every couple of sets.  If they jam, the safety of the system just went completely out the window!


APPENDIX: OB4 soft shells

I do not recommend the soft shells.  I used them for almost a season, and they performed acceptably, taking me to within a few buoys of my best.  However, they are too loose around the ball of the foot to achieve optimal performance -- especially if you are used to a rubber boot because those are very tight near the toes.  They are also not as comfortable, more complicated to setup up and use, and lower quality than the OB4 shells (which rock!).

But in case there is any value in my old soft shell setup information, I’ve moved that here.

Setup:  The P80 shells have oversized holes, so there is plenty (too much actually) of freedom to position them relative to the plate slots.

Cut off and seal the rear toe

If you have a suitable table saw or access to a machine shop, this may be a trivial task for you.  For the rest of us, a really nice way to get it done is with an Oscillating Tool.  A cheap ($40) one of these will do the job, and is a really cool tool that you’ll probably use again.  The “flush cutting” blade seems to work best, but be warned that if you hit one of the rivets, that blade is toast and you’ll have to go get another one!

Of course, make sure you remove the liner AND any plastic pieces or anything else that is removable before you start the chopping.  And seriously do wear hard gardening gloves and eye protection.

You may also need to cut some sole insert or something – ordinary scissors should be able to handle that.

After cutting it the way you want, you’ll need to apply a thin layer of Epoxy all around where you cut it.  This is needed to prevent any cloth portions from unravelling.  If your boot is 100% plastic, this is probably not necessary.  As far as I can tell, pretty much any variant of Epoxy works fine.  One good tip is to buy the absolute cheapest small paint brush you can find (should be under $2) and plan to just throw it away when you’re done.

Depending on how much you need to move your boots to get the spacing right, you may also need to increase the size of the flat section cut into the plastic on the bottom, so that they still cinch up tight to the plate.  The perfect tool for this is … the flush cutting blade on an Oscillating Tool!

Mount boots to plates

One thing that I struggled with quite a lot was getting the boot to stay where I put it (relative to the plate).  Those degrees of freedom that were so useful when setting up, become a liability when you’ve got it where you want and don’t want it to move!

But I’ve found a solution I really like.  Firstly, you need to remove any non-stainless components, such as the “sombrero” shaped washer that comes with a Rollerblade boot.  In the back, you need to remove this by slipping it out the back:

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Inserting new washers can be done similarly, and rubber washers can be folded in.  Here’s the “stack” that I settled on after many mediocre-to-failed experiments:

Stainless T-nut (came with it)

¼” rubber (aka neoprene) washer, ¾” diameter.  (I have only found 1 ¼” diameter so far, which is fine but curls up a little.)

5/16” stainless steel washer, 1 ¼” diameter

¼” rubber washer, 1 ¼” diameter

(bottom of boot)

(OB4 plate)

stainless steel hex head bolt ¾” 20-thread

Without the boot and plate, these components look like:

20140826_193954.jpg

Skip this paragraph if you don’t care why this combination works, but for the curious:  The rubber washer on top compresses enough that the T-nut locks and doesn’t spin.  The stainless washer holds the overall structure.  The rubber washer on the bottom both compresses to match the contour of the boot and has much higher friction than steel.  With all these pieces in place, the hex head can be used to apply some serious torque without fear of stripping.

Then crank this down TIGHT.  This holds much, much better than the hardware that came with it, and it also removes the pieces that would eventually rust out.

This combination has held with zero maintenance for nearly a year.

When you’ve get them where you want relative to the plates, use a metallic Sharpie to place various pairs of marks on the boot and plate so that you can easily check if they are in the correct place.  At least one pair of marks in the front, back, and side are needed to lock down all of the degrees of freedom.  I suggest a technically-redundant pair of marks on both sides, since that can make it easier to find a mark you can see while tightening.

Any time you release, re-examine all the marks you made. The force of a release may cause something to move.  If so, loosen up the screws, reset the boot to the marks, and then crank ‘em down again.

If you do all of that, the boots should never slip while skiing, except possibly in a major crash & release.

Putting them On

I suggest, at least as a starting point, that you run the low part of the boot (whether that is buckles or laces or whatever) snug but not tight.  If you crank the bottom down it’s easy to make your foot cramp.  A properly set boot is comfortable for a long stay in the water.

The most important element of putting on the boot is the tightness of the top buckle.  If you’re coming from rubber, as I was, you’ll want this to be surprisingly loose.  But actually I think nearly all skiers will want it relatively loose.  Counter-intuitively, it is hard to get good leverage when the top buckles are tight.

I suggest using a variety of colored Sharpies to mark the teeth, so that you can experiment and then be able to set the top buckle exactly the same after you figure out what works best for you.  This is a critically important tuning parameter.  I have found that even one tooth is a perceptible difference in ski performance – maybe almost as much as a .01” change of fin length.

<picture of my setting showing the teeth colors>>

The best way to actually get into the boot is not yet clear to me.  When the liner is wet, it seems to be easier to put the liner on your foot and then the foot/liner combo into the shell.  But sometimes that doesn’t quite feel right – almost like there is some lump somewhere that doesn’t go away no matter how I wiggle it around.  I’ve found myself reinstalling the liners with my hands, smoothing everything using my fingers to check it, and then putting my foot into the fully assembled boot.  It requires some struggle when it’s wet, but ultimately has felt more comfortable to me (so far).

I’ve considered putting the boots completely on in the boat, and then stepping to the platform and snapping them in.  But I have a fear that I might snap them in wrong and not be able to see it!