Many explorers are surprised to find that there are different categories of mountaineering boots available, and this often causes a lot of confusion. Below you’ll find the different categories which range from B0 to B3, and an explanation of each detailing what they are suitable for.
B0 boots are flexible in the soles and uppers, making them comfortable straight from the box and great for general hill walking below the snow line. Even with modern flexible linking bars, crampons will not be able to flex as much as these boots. This flexing disparity places undue pressure through the binding and can cause your crampon to pull loose with potentially disastrous results. You may also find that crampon straps dig in through the softer upper fabrics leading to significant discomfort. So for reasons of comfort and safety, B0s should be avoided for use on snow.
All round four season walking boots, robustly constructed for long mountain days and scrambles and with cross-over potential for those looking to do a small amount of winter hill walking. The midsole is stiffened while uppers may be leather or fabric, often supported by a generous rubber rand or synthetic leather reinforcements. Combine only with C1 strap-on crampons which offer the best flex. A B1/C1 combination will be adequate for many UK winter fell walks and gentle snow plods.
The best bet for regular winter hill walkers tackling long days in snowy conditions. Both midsoles and uppers will be stiff and supportive, but with just enough flex to sustain a regular walking action. Thicker uppers lend slightly more warmth. There will be a heel ledge to allow fitting of a C2 crampon for the most secure fit and versatile performance. Suitable for the winter Munro bagger, the low or mid grade Scottish Winter climber and the summer Alpinist.
Designed for full-on mountaineering, mixed and ice climbing. B3 boots have the stiffest soles and uppers available, giving solid lateral and medial support for front pointing, step-kicking and traversing on steep terrain. This category includes high altitude double boots as well as lighter technical climbing models. Heel and toe ledges allow fitting of C3 crampons to take advantage of the easy step-in attachment system of heel clip and toe bar.