ThermoBall Boots

Find the right size boot

A boot should fit snugly and hold your foot securely in place, without causing pain or pressure points.

• Measure your feet and consult the brand’s ski boot sizing chart
• If possible, try boots on in person

Consider the last width

Last is the width (mm) of the inside of the boot at the ball of your foot.

• Narrower last: Ideal for narrow feet or those who want a tighter, high-performance fit   

• Wider last: Better for wider feet or those prioritizing comfort

Understand ski boot flex

• Softer: Comfortable and forgiving; great for beginners or smaller skiers

• Medium: Best for intermediate to advanced skiers; balances comfort and responsiveness

• Stiff flex: Ideal for expert skiers; prioritizes performance

How long will you be on the trail?

• Hiking shoes: day hikes or ultralight backpacking
• Hiking boots: multi-day treks with heavier loads

What upper is right for you?

• Leather: water- and abrasion-resistant, durable
• Synthetic: lightweight, break in easily, dry faster

Look at the lugs

• Deep, thick lugs improve grip
• Wider lug spaces sheds mud and offer good traction

Check crampon compatibility
Mountaineering and winter hiking may call for crampons. Narrow your search for boots with crampon compatibility.

Understand boot flex

• Soft flex: Comfortable; ideal for beginners or recreational riders
• Medium flex: Balances all-mountain performance and comfort
• Stiff flex: Maximum support for edge power and control at high speeds

Match riding style to flex

• All-mountain: Soft to medium for most riders; stiffer boots for racers
• Freeride: Stiffer for edge power and control at high speeds
• Freestyle: Softer for quick response and maneuverability in park terrain

Boot lacing system

• Dial lace: Uses one or two dials attached to cable for precise fit, higher cost
• Hybrid lace: Combines a dial system and traditional laces
• Traditional lace: Tried-and-true and easy to replace but can loosen during rides
• Quick pull: A single-pull lacing system that's fast and allows zonal tightening

Find a good fit

• Boots should feel snug and secure without cramping your feet
• It's OK for toes to barely graze the boot's toecap
• A snug heel fit is also key

Choose based on your activity: 

• Insulated boots are warm and comfortable after breaking in; ideal for long approaches. 

• Three-season boots are light and versatile for hiking and scrambling; they have a lower price point than the others. 

• Plastic mountaineering boots are durable, rigid, waterproof but bulky and heavy; commonly found as rentals 

Do you plan to do much hiking in your boots? 

• Three-season boots: lightest option for alternative activities like hiking and scrambling. 

• Insulated boots: not as light, but light enough to work for approach hikes. 

• Plastic boots: exclusively designed for mountaineering.  

Crampon types 

Find a good-fitting mountaineering boots first. Then, find crampons to fit your boots. Your crampon compatibility choices are strap on, semi-automatic and hybrid.