Ski bindings, the metal and plastic contraptions that hold you on, or let you off your skis, have come a long way since the bone snapping bear traps of the fifties. Now we hardly think about them. In most cases, they have become so sophisticated that you need to be a rocket scientist to understand the technicalities.

I must confess that I could always tell you the name of the ski I was on, but would be often hard pressed to tell you the name of the binding that was doing such a wonderful job holding me on and letting me go with such precision. There are times, however, when they may let you down - usually because they have not been adjusted properly.

There is now a standardised din setting for all makes of ski binding so that the numbers on the dials mean the same regardless of the make. They can be adjusted to suit the weight and expertise of a skier - the higher the number the heavier and/or better the skier - generally. They should be tightened so that within a reasonable margin they will both hold the skier onto the skis and then let him go when necessary. The back binding releases to prevent him from breaking his leg, and the front one releases to prevent him twisting his knee ligaments. For reasons I won