I have posted this numerous times over then years, but seems like this is time to interject this into this thread!
So here goes!
From Vermont Safety Research
Q#5: If my bindings are releasing inadvertently, how much should I crank them up?
Subject: Separating Hardware from Software Problems
Answer: STOP!! Put away the screwdriver and study the following:
- Most retention problems are not related to the release setting and many are not even caused by the equipment at all. Often release, retention, and even performance problems are Software--that is skier--NOT Hardware related. Talk the problem over with a well-trained and experienced binding mechanic. If you have trouble finding a shop that will listen, check our SHOP LIST for shops that have sent staff members to the Ski and Snowboard Mechanics Workshop. If they don't have the answer they will at least have an idea of where to find it.
The RATCHET Effect -- A good example of the rush to readjust is what we call the Ratchet Effect on the release adjustment screw of competition bindings. Race bindings are tightened for a variety of reasons (most of them wrong), but are rarely loosened. All research efforts to date show that the magnitude of the load a skier applies to a modern binding toe piece decreases with speed (even during competition) and yet all problems of retention (inadvertent release) are blamed on the binding setting. Over time competitors at all levels employ ever increasing release settings, usually at both heel and toe, to address problems real or imagined. Setting increases are even precipitated by rumors of someone else's bad experience. This practice is dangerous and unnecessary.
PLEASE NOTE: The discussions that follow are intended to motivate the reader to be observant and accurately report problems involving the release/retention system to a qualified shop mechanic. The hypothetical hardware problems are rare, especially for well-maintained equipment. However, the software problems described below can be real for any skier using even the most current bindings. To diagnose any retention problem, provide your shop's mechanic with a few critical pieces of information:
- What were you doing before you and the ski parted company?
- What happened to the ski immediately after release?
- Which way did you fall?
- What was the position of the heel piece when you recovered the ski?
The FLEX Effect -- Inadvertent releases experienced by racers and hard/fast skiing non-competitors are often the result of the inability of toe and heel piece to stay the same distance apart during rapid flexing and counter-flexing of the ski--what we call the Flex Effect (or the Effortless Release). The most common cause of this problem is a sluggish forward pressure mechanism in the heel piece which can cause a gap to form between boot and binding and thus allow the boot to escape without releasing the binding. Cranking up the release adjustment screw at heel or toe has no effect on this phenomenon and may even exacerbate the problem
A Sluggish Forward Pressure Mechanism In The Heel Piece -- If the ski continued to go in the same direction after you two parted company, and the heel piece was found in the closed position, it could be the Flex Effect. Many times your mechanic can solve the problem by simply cleaning, lubricating, and correctly adjusting the forward pressure mechanism. With certain binding models, however, interference between the underside of the heel piece and the top surface of the ski may require the use of shims (small washers) to raise the heel piece slightly.
Thick Lifters And Soft Skis -- But the problem could also be complicated by excessively thick lifters under the binding or a ski that is very soft under foot. If you feel you need lifters, you should consider binding models with a lifter function built-in, and if you are partial to really soft skis, your best bet may be a binding model with a band or bridge connecting toe and heel piece, designed to allow either toe or heel to float with respect to the ski. These free flexing models make flex/counter-flex much easier for the heel piece to handle.
The HOUDINI Effect -- On the other hand, if the heel piece is found in the closed position and you are pretty sure from your own trajectory (after you and the ski parted company) that you were leaning forward at the time, the problem may be insufficient forward pressure. In this scenario, which could be called the Houdini Effect, the heel piece begins to open and thus presents an inclined plane to the boot's heel ledge. A little counter flex of the ski can also help to increase the mechanical advantage of that inclined plane, which then drives the heel piece rearward, thereby allowing the boot heel to escape upward from the heel piece. Since the heel piece did not actually release, the heel lug magically snaps back into the closed position, thus hiding its involvement in the affair. This condition can usually be reproduced by a binding mechanic with the aid of a ski binding test device. If the Houdini Effect is confirmed by the mechanic, the solution is usually to clean and re-lubricate the forward pressure mechanism and then increase the forward pressure adjustment. However, if the forward pressure spring is damaged or weak, for whatever reason, you may have to replace the heel piece or more likely, the entire set of bindings.
The JET Effect -- Insufficient forward pressure can also lead to an inadvertent separation of the boot from the ski binding during a (pardon the arcane terminology) jet turn . In this case the ski leaves your boot and shoots up and forward as you come off the mogul. This Jet Effect can occur with bindings that offer upward release at the toe as well as with models that are not designed to release upward at the toe at all. However, the problem is most often encountered among models that control upward release at the toe with the forward pressure mechanism of the heel piece. Because the ski flexes dramatically as you come into the mogul and then counter-flexes as you jet from the mogul, the real problem may not be just a weak forward pressure spring, but any of the problems associated with the Flex Effect discussed above.
The BOW Effect -- However, if the ski stays in the same place or shoots rearward following release, it may be a totally different problem. It is possible through the execution of poor or inappropriate technique to produce an inadvertent release of the heel piece at virtually any setting. The event has been termed the Bow Effect because, like the archer who allows the bow to slip from his grasp while flexing the bow in preparation for attaching the string, the skier flexes the fore body of the ski in reaction to a bump or rut thereby storing the energy that propels the ski rearward after release.
Poor Technique 'Pulls' The Heel Piece Open -- The inadvertent release is precipitated by the skier driving the shin rapidly forward at the same time as the forebody of the ski flexes sharply upward. It is most likely to occur to a ski that is only partially weighted. The inadvertent coordination of these movements by a skier who is otherwise erect and in balance can put the lower leg momentarily in tension, thereby allowing the skier to pull the heel piece open with no apparent effort. This classical example of poor technique (bad software) can only be avoided through education--smoother, better coordinated technique. Cranking up the heel piece is not necessarily the solution. Once learned by our testers, this scenario could be repeated, even at release settings on the heel piece well beyond the setting range of any binding now available to the public.
Wide Tip, Narrow Waist, and Soft Flex -- In theory the Bow Effect is most common with relatively soft flexing skis and skis which are much narrower in the waist than the tip, especially when used in conditions which allow the ski under foot to sinkwith respect to the shovel. But virtually any ski has the potential to exhibit this effect if used improperly.
You Can't Compensate For The Bow Effect -- The Ratchet Effect is a very real danger for skiers who fail to recognize and deal with the Bow Effect. In the laboratory we have simulated the Bow Effect and compared the results to a simulation of the classic weighted forward fall. In these tests the difference between what our load cell (an instrumented artificial leg) sensed in the simulated forward fall was more than four times what the load cell sensed in the Bow Effect simulation. The lesson should be clear. If you try and compensate for the Bow Effect by increasing the release setting of your heel piece, you will put your leg at risk in any weighted forward fall, and yet you may still not have solved your retention problem.
The SUPERMAN Effect -- Another software problem, created and controlled completely by the skier, is what some might want to call the Superman Effect. The problem occurs most often at relatively low speeds and is usually precipitated by the environment (snow conditions).
Pitch, Roll, And Yaw -- Release setting requirements are based upon the loads involved in skiing under packed powder to powder conditions. Using the analogy of flying a plane, the movements you make to maneuver a ski are largely pitch(moving your knees forward and backward) and roll (moving your knees from side to side), not yaw (twisting your lower legs clockwise or counter-clockwise). Yaw only comes into play during a transition, as we end one maneuver and begin another.
Torque Is A Consequence Of Less Than Perfect Technique -- A substantial twisting load (torque) is not required to maneuver a ski. Torque is largely a consequence of less than perfect technique. Applying greater twisting loads than are required for the maneuver is like applying excessive rudder control on an aircraft. You probably won't fall out of the sky but by making an uncoordinated turn you may lose speed, and at the least you are going to waste fuel (effort).
Mass, Gravity, And Muscle Strength -- In skiing we are limited by our mass, not our strength, in how great a twisting load we can actually apply to the ski and still remain in control. Under most conditions all we have to work against is gravity. We can in fact consider ourselves one-legged skiers because, in most situations, we lack the ability to work one leg against the other. We can not, for example, engage both inside edges or both outside edges at the same time while applying opposing loads in twist on each leg. If we do, our skis will steer apart or cross. However, when in heavy powder, breakable crust, or just plain crud, we have the ability to use our strength because we have something to push against. But the strongest person you can imagine does not need a stronger steering wheel, shifting lever, or brake pedal--no type of driving requires that--and skiers shouldn't crank up their bindings just because they have the strength to release them in certain situations.
Don't Blame The Hardware...Improve Your Technique -- Unless Superman turns on his powers he is just Clark Kent. In unguarded moments on the slope we are all Clark Kent and risk serious injury if we are using unnecessarily high settings. Don't look to hardware solutions for software problems. Whether you have succumbed to the Superman Effect or the Bow Effect look to improvements in your technique before you blame the hardware and grab a screwdriver.
When To Re-Evaluate Your Release Settings -- If the ski and skier part company with the ski heading in a different direction and rolling over almost immediately, and if the heel piece is found in the closed position, probably an honest (possibly even necessary) release of the toe piece occurred. Likewise, if you fall forward, with the ski tumbling after you, and you find the heel piece in the open (cocked) position, you probably had an honest (possibly even necessary) release of the heel piece. If you feel the release was unnecessary, the problem persists, and you and your mechanic have ruled out all of the above, it may be time to re-evaluate your release settings.
How To Reclassify Yourself -- You can most easily modify your setting by reclassifying yourself for Skier Type. The Skier Type Classification Chart defines three Skier Types: I, II, and III. But it makes absolutely no sense to crank up the toe piece for a heel problem or vice versa. Therefore, we suggest you reclassify yourself on the shop's service agreement using a [ / ] to separate toe piece from heel piece classifications. So, if you were a Type II and you decided you needed more retention at the heel you could classify yourself as a II/III. Increasing you Skier Type Classification by one category has the effect of increasing the release torque of those units by 15%. But remember, as you increase your margin of retention you decrease your margin of release thus increasing the risk of injury from the ski acting as a lever to cause injury to your lower leg in a fall.
Recalibrating Your Bindings To The New Settings -- If you go ahead with this reclassification, your mechanic will consult a table provided by the binding manufacturer to determine the Initial Release Indicator Value separately for toe and heel piece. In addition to your Skier Type the mechanic will also consider your weight, height, and age. After adjusting your bindings to the initial settings, the mechanic will release the bindings with a Ski Binding Test Device and then compare the results to the Release Torque Ranges provided by that same chart. If necessary, the mechanic will fine tune the binding setting until each unit falls within the proper range. The mechanic will then record the Final Release Indicator Value for each unit on the service agreement.
Marking Your Skis So You Don't Forget -- If retention has not been a problem you might even consider using the method above to experiment with lower release settings. But in any case, to keep track of what you have done, we recommend that you write the Final Indicator Value close to each unit in the area between the toe piece and heel piece with a paint (or indelible) pen. So that you don't forget the Skier Type decisions you made, we recommend you include them as well. To accomplish this for the example above in which we used a Skier Type II for the toe piece and Skier Type III for the heel, you might consider using a convention such as II=[?] (where [?] is the Indicator Value) for the toe piece and III=[?] for the heel piece. That way, if you do find yourself in a situation that DEMANDS an IMMEDIATE correction to your release settings, you can make the temporary change yourself and then later return your bindings to the original setting or reopen the Skier Type discussion with your mechanic.
Caution -- Skier Type is a term intended to help you and your mechanic communicate better. Each definition has two parts. The first part is a brief guide that covers a general description of the type of skiing that applies to each classification. The second part is a warning of the trade-off involved in making each Skier Type selection. Although the second part is an irrefutable consequence of your choice and the laws of natural, the first part should be viewed as a helpful hint that may not work for everyone. It should, therefore, not be considered a hard and fast rule but a work in progress that may be redefined when necessary. A new definition that has been developed in recent years for those with concerns that can not be satisfied by Skier Types I through III, is the concept of a I(-) for settings lower than would be provided by Skier Type I and a III(+) for settings higher than would be provided by Skier Type III. Such settings have been termed Discretionary and should only be requested when all other options have been exhausted.--- CFE