What's wrong with such an innocent pair of snow pants? They're warm, waterproof... and so cozy!
And that's about all they will offer you in the event of a crash; they may keep you warm and dry while you're cursing yourself for not buying real riding pants. I'm sorry to break this to you, but that's exactly what you need to prepare for. So why isn't a toasty pair of snow / ski pants good enough to ride in?
As you can see, these pants (and anything not motorcycle specific) refuse to cooperate should you separate from your vehicle. And although we try our best to keep ourselves attached to our beloved motorcycles, it doesn't always end up that way. I'm not even talking about going 60-70mph. You can do plenty of damage to your body by just crossing the street and tripping off the sidewalk. I can't tell you how many times I've hurt my back just stepping off the curb weird, or trying to avoid falling on my dog so I end up with a bruised knee because I chose to hit the ground instead. Now add some speed into the mix and you have a really good chance of getting injured.
Two crucial points of impact are your hips and knees. If you accidentally trip while walking across your living room, I can guarantee that if you hit the ground these two points will make contact with the grand. Oh and probably the palm of your hands (so that's why you need gloves). But that's going to be the next installment. As far as this one, those two points need some protection so your bones don't take the full impact of that fall.
Additionally, these kinds of pants are for falling down on soft, powdery piles of snow. Not pavement. And pavement is not going to be nice when they start rubbing against the ground. None of your snow/ski wear is designed to stay together in the case of an accident, or hold up if there's any friction between you and the ground. The last thing you want is your flesh to make contact with pavement.
And we can't forget about fit! Something you won't be doing while skiing is sitting. Well, if you're doing things the right way of course. :-) Riding pants are designed for maximum comfort in the seated position. That means the back side should be higher rise and cover you well above your hips, towards your waist. There's no pulling from the hips to the knees, no bunching fabric behind the knees.
But motorcycle specific riding pants, such as these beautiful Rev'it Factor 3 Women's pants have even more creature comforts built in. See those small folds above the knees? Those are there to maintain comfort while you bend your knees over your feet pegs. The front is a slightly lower rise than the back. There's even a small stretch panel on the lower back so it won't pull when you sit. And every piece of fabric on these pants are cut out for riding positions. Lots of sitting!
If you're thinking about riding pants (and I hope you all are, no matter what you're riding), remember that motorcycling requires the same technical features as any other sport. And more importantly, the added safety and protection that you simply won't find in any other piece of technical gear.
In case you missed the first installment of Wear This Not That, Check It Out!