Traction devices and body weight.

User weight doesn't matter for selecting a crampon. Just use the right crampon for the terrain you are in.

In other words, for low angle terrain, anything that fits should work. As it gets steeper (but still just walking or maybe french technique), I like to switch to a 10 point general mountaineering crampon. For steep mountaineering terrain, I switch to a 12 point crampon because I want more spikes in the front for german and american technique.

^^ Those examples are all just personal preference though. I know people that ice climb in 10 point strap crampons as well as people that use aggressive ice climbing crampons for walking down any icy trail. The point is, crampon design is mostly tailored to the terrain you are on, not how much you weigh.

With the way force vectors add, yes, the heavier person has a greater vertical force pushing the points into the ice but also a greater horizontal force trying to slip his feet out from under him. So the lighter person's points might not dig in as deep but they also have to overcome less of a horizontal force that's trying to shoot their feet out from under them.

I'd GUESS it's probably a wash. As long as they fit then similar crampons probably work as well no matter what your weight is, within reasonable limits.

Thanks for the responses. I hadn't really factored in the horizontal force difference (long time since my last physics class) but that's a valid point.

I'm not quite convinced, though. Partly it's observation: two people wear Kahtoola Microspikes, and the light person can easily slide their feet sideways, while the heavy person is dug in solid. I guess it's the difference between holding one millimetre of ice, and three or four.

I think I'll try sharpening the spikes. Might need to go with a more serious crampon.

Climate change sucks. Once upon a time, the main thing you needed here in the depths of winter was snowshoes.

Well, also there's ice and then there's ICE. In truly ridiculously cold conditions with pure, hard ice that almost looks like glass the light person might not dig in at all. But I'm thinking that's not very common.

A triangular point on a traditional crampon would dig in more for the heavier person but be needed more for the heavier person so it is close to a wash.

But there are road conditions in which a semi truck gets MUCH better purchase than a car. I look at my tire marks and my tread and/or tire chains haven't "bitten" into the hard-packed snow much at all – it leaves a shallow indent that it can slide out of easily. But with 40,000 to 80,000 pounds vehicle weight, the truck leaves much deeper grooves and deeper chain marks that provide considerably more purchase.

So my mental model would be that if both body weights are getting purchase, it's a wash. But that there is a "minimum body weight" for the conditions/gear.

If it is a short stretch, anyone can stomp harder on each new step to set the points deeper. Also, pause just 1/2 second before putting weight on the new step – that give the snow in the lugs a moment to refreeze to the base snow. It's a weird gait, but one that mountaineers learn to use.

Dean F. mentioned 'pure, hard ice that almost looks like glass.' Yup, that's the stuff. And it's everywhere. I measured 6 inches of clear hard ice on a nearby trail this weekend. You can see the ground through it. It was -15C.

As I say, it's a climate change thing, compounded by our coastal location. The ocean's warm, the air is polar. More and more often, we see rain and rising temps, which melts and waterlogs the snow. Next comes freezing rain and more ice builds up before the temp plunges to -10C or below and stays there. Now what used to be snow is hard, shiny, thick ice. These conditions also cause freeze and thaw cycles in any running water, so the little brook I stepped over in September has now turned a 300 metre wide hollow into a skating rink. Crazy, I tell you.

In vehicles we do exactly what David describes, studs plus weight (sandbags, cement, cord of hardwood…). Not what a hiker wants to hear, though. Still, if the alternative is to stomp hard and walk slow, over an entire trail, for hours, then weighting the pack just might be the best answer.

"But there are road conditions in which a semi truck gets MUCH better purchase than a car. I look at my tire marks and my tread and/or tire chains haven't "bitten" into the hard-packed snow much at all – it leaves a shallow indent that it can slide out of easily. But with 40,000 to 80,000 pounds vehicle weight, the truck leaves much deeper grooves and deeper chain marks that provide considerably more purchase."

I have the opposite experience. Being able to drive over a mountain pass with chains on the car while seeing a fully loaded
and chained sanding truck slide sideways off the road from a standstill.