This is a topic that seems to resurface at least once a year. In our archives are some lengthy discussions on the plusses and minuses of boot flex.
I'll offer a viewpoint that that is contrary to some commonly accepted notions. There's a lot of talk currently that today's softer, deeper sidecut skis work better with softer boots. I don't agree! True, today's skis usually perform best when pressured in the center "sweet spot," and do not usually need extreme tip or tail pressure. But just because we don't as often need these things is no reason to give up the heightened control of fore-aft pressure that stiffer boots provide (if properly operated).
Keep in mind that your skis could not care less whether your boots are flexed or not. They do NOT respond to "boot flex" and flexing your boots is NOT important as far as ski performance goes! Skis respond to pressure and torque (twisting forces that steer them and tip them).
The boot is simply a "handle" for your ski. It is what you use to manipulate and control the ski. A flexible handle does not give you as much, or as precise, control--simple! Stiff boots transfer your every movement directly, and completely, to the ski.
On the other hand, a flexible handle does mute any "bad" movements you might transfer to your skis. Stiff boots are unforgiving of errors and inconsistencies in technique. This is one reason softer boots are more user-friendly for beginners.
And stiff boots restrict the range of motion of the ankle, especially fore-and-aft. Ankle flexing is a big part of maintaining fore-aft balance when we bend and straighten our knees, hips, and other joints in everyday life. Stand up in your bare feet and then crouch down low--your knees and hips bend, and your ankles flex ("dorsiflex") and your heels lift, right? With this combination of joints flexing, you are able to keep your balance. But ski bindings hold your heels down, and stiff boots restrict your ability to flex your ankles. So one of the most important skills to learn for skiing is an entirely new combination of movements of the knees, hips, spine, and arms to compensate for the lack of foot and ankle motion when flexing and extending.
Again, for beginners who have not yet learned these ski-specific movements, softer-flexing boots allow a bit more ankle motion that enables them to move more "normally." But the sacrifice in control through this soft "handle" is a poor substitute for learning the right movements and skills of skiing!
Top skiers are able to flex and extend their bodies through a very wide range, with the stiffest of boots (and without trying or needing to "flex" the boots at all). And they are able to control the fore-aft pressure on their skis VERY precisely with their stiff boots, with subtle, minimal movements of their feet and legs, transferred through the stiff, precise "handles" of their stiff boots.
So--if you haven't figured it out yet, I am not a proponent of soft boots, in general. Yes, stiff boots take more learning to be able to handle. Yes, soft boots are more forgiving of the errors that we ALL make. But only stiff boots, combined with refined technique, offer the ultimate degree of control.
That said, boots can still be too stiff, even for experts. While a good skier can absorb the largest of moguls even with the stiffest boots, small washboard-like bumps and vibrations happen too quickly for active absorption movements. A little smooth boot flex dampens the sting of these bumps, and allows the skis to glide more smoothly as well. Boots that are too stiff, even with perfect technique, will slow you down in a race course!
Mogul skiers often prefer somewhat softer boots. While they do sacrifice some control, and in theory they should be able to ski bumps even with concrete boots, one big mistake in moguls will hurt BAD with very stiff boots! And we all make mistakes.
Finally, the stiffer the boot, the more critical its setup becomes. Particularly critical is the amount of forward lean (which is is the combination of the angle of the cuff and the angle of the entire boot as it sits on the bindings). If the boot is too upright, the skier will need to bend forward awkwardly at the waist and reach forward with the arms to balance, and will be unable to bend the knees very far without losing balance to the rear. Too much forward lean requires the skier to have to hold the torso too upright, and prevents him/her from extending to a tall position without pressuring the skis too far forward. So once again, for the average skier who does not expect to have an alignment specialist set up his equpment, a little more flex compensates for improper setup (with the usual sacrifice of some control).
So boot flex is only part of the issue. Proper setup and proper technique are both critical! The better the technique, and given proper setup, the more advantageous stiffer boots become.
[ November 08, 2002, 11:45 AM: Message edited by: Bob Barnes/Colorado ]