Basically if your boot bends so much when you take a step that it can wiggle its way out of the crampon then you ll need stiffer boots.
Crampons for flexible boots.
Crampon boot compatibility use b0 boot flexible b1 boot semi stiff b2 boot fully stiff.
As they use strap on bindings they can be used with any hiking boots as long as they don t have too flexible soles like summer hiking boots.
Crampons similar to boots are rated on their flexibility and by how much support they provide.
Crampons generally fall into three groups flexible semi rigid and rigid and the more flexible your boots then the more flexible your crampons will have to be.
For highly flexible boots get crampons with a flexible center bar that connects the front and back.
In general the lower ratings are for snowy backpacking and the higher numbers are for alpine ice climbing.
Crampons are graded c1 c2 and c3 relative to their flexibility and general compatibility with different styles of boots.
They are designed to fit boots that are fairly flexible but will still fall off if you wear them on flexible summer hiking boots.
These crampons are known as basket binding or flexible crampons.
You can wear aluminum crampons with sneakers and strap on bindings for light mountaineering or glacier travel just make sure the flexibility is similar.
Flexible crampons c1 on the other hand are primarily designed for hiking and mountaineering on flat and semi steep terrain glacier travel and similar.
Instead of picking your boots up to test stiffness compressing them like some cobbler s arm trainer why not use your body weight instead.
Bring along your boots when shopping.