The Salomon S/Pro Alpha C BOA®

The Salomon S/Pro Alpha C BOA is a performance alpine ski boot for skiers with narrow feet. It pairs a 98 mm last with a BOA® Fit System dial on the cuff and two traditional buckles on the lower shell.

The "C" in the name stands for cuff, which is where the dial sits. Salomon has also introduced a new shell construction called ExoDrive and a lower pivot point called Powerlink. Together, these changes aim to hold the heel down and send power to the ski faster.

The boot suits keen skiers who want precise edge control on firm snow. It also suits anyone who has struggled to find a boot that grips a slim heel without crushing the forefoot.

A ski boot's last is the width of the shell across the forefoot, measured in millimetres. A 98 mm last is a low-volume fit, meaning it leaves less empty space around the foot than a standard boot.

Many ski boots sit between 100 mm and 104 mm. A 98 mm shell suits skiers with narrow forefeet, low to medium insteps and slim heels. These are the skiers who often feel their foot swimming inside a mid-volume boot.

Fit still depends on the whole foot, not just width. Instep height, calf shape and ankle position all change how a boot feels. A boot fitter can check all of these in a few minutes, which is why trying boots on matters so much with a low-volume shell.

The Alpha C BOA has a narrower 98 mm low-volume last and a new ExoDrive shell built to hold slim heels. The Supra C BOA has a 100 mm medium-volume last and Salomon's ExoWrap shell for average-width feet. Both use a BOA® dial on the cuff and two buckles on the lower shell.

The two boots look similar, so it helps to compare them side by side.

The fit is the biggest difference. A 98 mm last leaves little spare room around the foot, so it grips a narrow forefoot and a slim heel. A 100 mm last is only two millimetres wider, but that gap is enough to change how the boot feels across the whole foot.

Skiers with average feet often find the Alpha too snug. Skiers with narrow feet often find the Supra too loose. A fitter can settle the question in a few minutes. They can also adjust the Supra's shell with Custom Shell HD heat-moulding if you need a little extra room.

The Alpha C BOA uses ExoDrive construction. It adds a third cuff overlap around the ankle, which wraps the heel more tightly. A lowered Powerlink pivot then sends energy from your shin to the ski faster.

The Supra C BOA uses Salomon's ExoWrap construction, which focuses on wrapping the foot and creating a smooth, progressive flex. It gives a more familiar feel and a little less of the tight, direct connection you get from the Alpha.

The Alpha C BOA comes in a wider spread of flex ratings, from softer models for developing skiers up to very stiff ones for experts. Our Supra guide lists the Supra C BOA in stiffer options only, at 115 and 130. Skiers who want a softer boot with a cuff dial will find more choice in the Alpha range.

• Choose the Alpha C BOA if you have narrow feet, a slim heel or a history of heel lift, and you want a direct, quiet flex.
• Choose the Supra C BOA if you have average-width feet and want a smooth, progressive boot with a cuff dial.
• Try both on if you sit between the two. The boot that holds your heel without squeezing your forefoot is the right one.

Our S/Pro Supra BOA guide covers the mid-volume range in full.

The BOA® dial winds a thin steel cable through guides on the boot. Turning the dial pulls the cable tight and draws the cuff evenly around the ankle and lower leg.

Traditional buckles pull plastic flaps together at fixed points. Each buckle creates a pressure line, and a skier can feel those lines after a few hours. A dial spreads the load across a wider area, so the cuff grips the leg without a single hard pinch.

The dial tightens and loosens in small steps, and each click changes the fit by a tiny amount. That lets a skier ease off the cuff on a long chairlift ride, then tighten it again at the top of a steep run. It takes seconds, and no gloves need to come off.

The two lower buckles stay on purpose. They give bootfitters and skiers familiar, separate control over the forefoot and instep. A skier can set the foot hold with the buckles and fine-tune the ankle wrap with the dial.

ExoDrive is Salomon's new shell construction for the S/Pro Alpha C BOA. It changes how the cuff wraps the ankle and how the whole boot flexes.

The key feature is a third cuff overlap. Most alpine boots overlap the cuff plastic in two layers. Salomon has added a third layer around the ankle, which wraps the heel and lower leg more tightly. That wrap holds the heel down in the pocket.

A 3D instep shell also anchors the buckle system directly to the cuff. When the skier tightens the boot, the force pulls the foot back and down into the heel pocket. Salomon says the shape also makes stepping in easier and avoids unwanted pressure on top of the foot.

The result is a boot that flexes as one unified system rather than as separate lower and upper parts. For a skier, that feels like a more direct link between the shin and the ski.

The Powerlink is a metallic piece that reinforces the ExoDrive system by linking the cuff to the lower shell. It sets the hinge point lower than on many boots, and it works with a larger cuff surface.

A lower hinge point gives the skier more leverage over the ski. Small movements of the shin turn into edge pressure faster, with less energy lost inside the boot. The bigger cuff surface spreads that pressure across the leg.

On snow, this shows up in three ways:

• Quicker edge engagement: The ski responds sooner when you tip it onto its edge.
• Smoother flex: The boot bends progressively rather than snapping forward.
• Better feel on firm snow: You sense the ski's grip earlier and can adjust before it slips.

Aggressive skiers on hard-packed and steep terrain will notice the difference most.

The liner is the soft boot inside the plastic shell, and it decides how the foot feels hour after hour. The Alpha C BOA uses a reworked S/Pro CF Expert liner with 4D construction and premium finishes.

A new edgeless Custom Tongue 2.0 sits at the front of the liner. Because the tongue has no hard edges, it presses less on the shin and instep. Skiers with high arches or sensitive instep bones will appreciate that.

Salomon has also used a thicker shell in key internal zones, paired with lower-density material to reduce vibration. Chatter from rough snow travels through a ski boot into the foot and shin. Less vibration means less fatigue late in the day and a smoother feel through bumpy or icy sections.

Salomon builds the boot so a fitter can adjust it. That matters because every foot has its own bumps, angles and pressure points.

• Custom Shell HD: A fitter heats the polyurethane shell and cuff, then the skier steps in while it cools. The shell moulds to the foot and ankle bones, and a fitter can open up tight spots by a few millimetres.
• Custom Tongue 2.0: The tongue can be adjusted to relieve pressure on the instep and shin.
• Heat-moulding liner: The liner shapes to the foot quickly, which shortens the break-in period.
• Screwed hardware: The buckles and BOA® dial are fixed with screws rather than rivets, so a fitter can replace or adjust them.
• GripWalk soles: These give a rockered, grippy walking surface and work with GripWalk bindings.

A first fitting is the best time to raise any concerns. Tell the fitter about old injuries, hot spots and how your last boots felt.

Follow these steps to set the fit correctly and keep it right through the day.

All three boots share the 98 mm last, the cuff-mounted BOA® dial, the ExoDrive shell and GripWalk soles. The difference is flex, which is a number that describes how stiff the boot is. A higher number means a stiffer boot that needs more strength and speed to bend.

The 120 is the powerful choice for advanced and expert skiers who drive their boots hard. Salomon builds it on the same shell as the stiffest boot in the range, then softens the flex slightly. It also adds a plusher liner and a 45 mm power strap for a smoother, more forgiving ride. Pick this boot if you ski fast on firm snow and want direct response.

Salomon S/Pro Alpha C BOA 120 (Men's)

The 100 is the balanced choice for lighter or intermediate skiers with narrow feet. It offers the same low-volume hold and heel retention as the stiffer boot, with a flex that bends more easily. Pick this boot if you want a secure narrow fit without needing a lot of force to flex it.

Salomon S/Pro Alpha C BOA 100 (Men's)

The 105 W is the strong, responsive choice for advanced women skiers with narrow feet. It pairs the 98 mm last with a women's-specific liner, a Light² footbed and a 45 mm power strap. Pick this boot if you want a slim heel held firmly on hard snow.

Salomon S/Pro Alpha C BOA 105 W (Women's)

Flex ratings are a guide only. Weight, height, ability and skiing style all change which flex feels right, so use these as a starting point and check with a fitter.

The boot suits a specific kind of skier. Match yourself against the list below.

• Skiers with narrow feet: The 98 mm last gives a slim, snug hold.
• Skiers who get heel lift: The third cuff overlap and ExoDrive shell target this problem.
• Confident piste skiers: Fast carving on groomed and firm snow suits the direct feel.
• Skiers who dislike buckle pressure: The dial spreads pressure around the cuff.
• Upgraders: If your older boots feel loose or sloppy, a low-volume shell can restore control.

The boot may not suit skiers with wide feet or high, thick insteps. A 98 mm shell can feel tight on these foot shapes, even after heat-moulding. In that case, the Supra C BOA is a better starting point.

Families buying for beginners should also look at softer, more forgiving boots first. Our ski boot buying guide covers the basics.