Originally Posted by Ghost
I don't see why the flex pattern you are looking for cannot be found in a boot without you having to buy after-market straps.
a) no liner is infinitely hard. By the time you've compressed the liner enough to put pressure onto the front of your boot, the person with the (pre-loaded! just like an MTB suspension fork) Booster strap has already pulled the back of the cuff forward.Side note: If the boot is flexed forward purely through weight shift, then the liner resilience has been bypassed. If the boot is flexed forward through dorsiflexion (say to avoid weighting the tip of the inside ski too much whilst pulling it back to under the hips) then only the liner resilience inside the lower part of the boot (clog) is in the force transmission path. I (ahem) firmly believe that there will be, in the near future, more elastic features for the lower part of the boot liner.
b) In order for your heel to stay down in the boot, your calf geometry will change inside the boot as the boot flexes forward. Therefore the hard limit of the tightness of your top buckle (and non-stretchable strap!) must be set loose enough to allow that. Within that hard limit, the Booster strap (pre-loaded! just like an MTB suspension fork) is more elastic than the liner, helping it bounce back towards your shin.
c) Yes the strap is matched to the flex of the boot. It has to be or it will bottom out by the time you've squished the liner, without putting adequate tension on the back of the cuff. The whole idea is that there is no discontinuity for very, very small forward motions between pure liner compression and forward shell flex. By the time it looks like a 'normal strap' there is no forward flex in the boot.Side note: 'accuracy' 'precision' 'no play' are bandied about chronically without attention to the capacities of the human. Consider that being able to just slightly move whilst applying a force actually may make the perception of that force more accurate. For example: try figuring out how heavy a suitcase is just by holding it with arm outstretched, without flexing the bicep, and without bending spine or knees to pick it up. Not so easy, huh?
I believe that being able to move whilst applying a force allows our judgement of that force to be more accurate. Therefore I object to the use of the word play to describe Booster strap action because it is clearly also applying a force to the back of a boot cuff whilst it is being stretched, and the word play has connotation of free play, i.e. no effect during motion or wasted motion. Call it "suspension travel" and I shan't object.