Cross-country ski gear goes sophisticated

There was a time when buying cross-country ski gear was a relief from the mumbo-jumbo high tech world of alpine skiing. I mean, you walked into a shop, picked out a nice pair of wooden skis - they all looked alike - a good leather ski boot, and that was it.

Now, just looking over the options in the latest cross-country skis and boots could make you wish for advanced degrees in chemistry and physics. (How torsionally rigid must my boots be anyway?)

A quick look at some of the recent developments in boot-binding combinations might sort out some of the confusion. Traditionally, fine boots have been leather and have had soles 75 mm wide, which conform with traditional three-pin bind-ings.

A few years ago, racers and elite skiers began using boots with a narrower extended sole in front of the shoe. These are called 50-mm boots (Adidases are 38 mm) and allow greater extension when a skier goes onto the ball of the foot. As bootmakers improved their models in the last two or three years, they worked to give them more lateral stability and often to make re-creational models warmer and lighter.

Usually, warmer meant a thicker 12-mm sole instead of the 7-mm thickness racers use. Lighter sometimes has meant synthetics, such as Trak's use of Gor-Tex, which is touted as water-repellant yet able to ''breathe,'' like leather.

At the same time, grooves in boot soles or heels and corresponding ridges in binding foot plates have contributed to lateral stability - particularly on downhills. Needless to say, the more innovations being made, the less there is a current ''standard.'' Hence, the boot you pick must go with its own kind of binding.

The two latest developments both seem significant. Salomon has come out with a boot-binding system that allows the greatest extension yet. Cross-Country Skier magazine has conducted tests that indicate a fine 75-mm norm leather boot has more lateral stability than the innovators have given it credit for.