Another of those little things that can easily cause a bit of head scratching. Ideally, if you’ve never done this then you probably should ask someone to show you how to do this. If you’ve done it and need a reminder (my first winter trip every year sees me fixing my crampons incorrectly! I’m hoping to remember the strap across the front this time!)
The images below are indoors, sorry, but it’s a little easier to get the images indoors with warm hands!
1 – Boot on Crampon – Make sure you put the proper crampon on the proper shoe. My crampons are almost identical to each other except for the double d rings which secure the straps which need to be on the outside to keep any excess straps away from your feet and so not a trip hazard. The bar underneath is also slightly curved in order to fit the left or right boot (check the image of the bottom of the boot below).
2- Tighten the crampon onto the boot (you may need to adjust underneath the crampon to ensure they’re the right length). Fold the front and rear plastic sections forward and ensure that the boot is sitting comfortably in the crampon. There shouldn’t be much air between the boot’s sole and the crampon.
3 – Strap under the front plastic part (that’s the technical term for it, honest!) and back through the upper hole.
4 – Across to the loop on the side of the boot, thread through and tighten. Ensure that the crampon is not loose.
5 – Across the front of the boot, over the laces.
6 – Through the D rings and finally back through the first D ring and tighten – but not too tight as you can restrict blood flow to your feet and get cold feet or worse.
It’s recommended that you practice doing this at home a few times, and it also means you can see how much excess strapping you’ve got. You can safely cut this down as too much excess can be a trip hazard, but don’t be over zealous or you’ll have to replace the lot! If you find it difficult indoors, then you’ll probably find it impossible with large gloves and a howling gale with biting wind chill.
Of course, this is only true for strapped crampons and you may be lucky enough to have step in crampons.
There’s a useful instruction sheet on the grivel site that works for all strap on crampons.
Here’s a vid that might help further.