110-Flex Carbon Skimo Race Boot
Scarpa Alien 5.0 Alpine Touring Boot
The Scarpa Alien 5.0 is a skimo race boot for competitors and skiers whose priority is vertical gain per hour. A hand-laid carbon shell and cuff hold the weight to 610 g per boot at size 42, and 76 degrees of cuff rotation is among the largest ranges available in any ski boot. A single-action Dyneema cord with the BOA Fit System closes the boot in one movement, which is where race transitions are won, and the 99 mm last fits a race foot rather than an average one.
Expert Fit Review
Fit profile and recommendations reviewed by CCBB bootfitters.
Is This the Right Boot for You?
Best For
Skimo racers and uphill athletes with narrow, low-volume feet who want the lightest usable boot on race skis 65 to 80 mm underfoot.
Consider Another Boot If
You want downhill capability or a fit you can modify. A hand-laid carbon shell at a 110 flex on a 99 mm last is a competition tool.
CCBB Boot Ratings
Uphill Efficiency
76 degrees of rotation at 610 g (size 42 EU)
Walking Comfort
76 degrees of cuff rotation
Transition Speed
Single-action cord with Speed Lock Lite
Downhill Performance
110 flex on a 99 mm carbon race shell
Rating scale: 5 = top of its class, 4 = excellent, 3 = good, 2 = specialized or below average, and 1 = limited.
CCBB Fit Profile
Overall VolumeLow
Toe BoxNarrow
Forefoot VolumeLow
Instep HeightLow
Heel HoldExcellent
Ankle HoldGood
PunchabilityVery limited
Heat MoldableYes
Why We Like It
- 76 degrees of cuff rotation is at the very top of what any ski boot offers, and on a long climb that is the difference you feel before any weight saving.
- At 610 g per boot at size 42 the hand-laid carbon shell and cuff put this among the lightest boots that can still be skied with control.
- A single-action Dyneema cord with BOA closes the whole boot in one movement, and Speed Lock Lite gives two forward lean positions rather than one.
- Scarpa publishes an Optimized Touring Pivot of 5 mm for this boot, so the toe can be mounted for the stride rather than to a shop default.
Best Uses
- Skimo racing and competition
- Uphill training and vertical records
- Fast ski mountaineering on narrow skis
- Athletes with narrow, low-volume feet
Bootfitter's Advice
The Alien 5.0 is sized in European whole sizes from 39 to 44, not Mondopoint, which is unusual and means there is no half size and no direct conversion from your usual boot number. A shell fit is not optional. The 99 mm last is a race last: narrow, low over the instep, snug at the heel.
Punching is very limited. A hand-laid carbon shell will not take the modifications a Grilamid shell accepts, and attempting them risks the layup. Fit work happens through the SCARPA Race 4.0 SL liner and a footbed. The 5 mm Optimized Touring Pivot should be applied at mounting.
Fit profile reviewed by CCBB bootfitters. Final sizing should be confirmed with a shell fit whenever possible.
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Technical Specifications
Manufacturer specs · Click to expand
Fit and Construction
Weight: 610 g per boot (size 42 EU)
Sizes: 39 to 44 European, whole sizes only
Last: 99 mm
Flex: 110
Range of Motion: 76 degrees
Shell: Hand-laid carbon fiber with a Pebax toe cap
Cuff: Hand-laid carbon fiber
Tongue: Synthetic
Features and Compatibility
Walk Mode: Speed Lock Lite ski/walk mechanism, two forward lean positions
Closure: Dyneema cord with a BOA Fit System
Binding Compatibility: Pin/tech (low-tech) bindings only. The Vibram UFO 4.0 sole carries no ISO norm, so the Alien 5.0 is not compatible with AT/frame bindings, MNC bindings, or traditional ISO 5355 (Alpine) bindings. Scarpa specifies an Optimized Touring Pivot of 5 mm for the toe mount.
Sole: Vibram UFO 4.0 sole in TOP85 compound. No ISO norm.
Forward Lean: 9 to 13 degrees, or 11 to 15 degrees
Liner: SCARPA Race 4.0 SL liner, heat-moldable
Liner Mold Time: Heat-moldable liner
Article Number: 12185/500
Notes: Optimized Touring Pivot of 5 mm, which belongs on the mount sheet
Compare the Scarpa Alien 5.0
Alien 5.0 vs. Scarpa Alien 1.0
The Scarpa Alien 1.0 is the boot below this one, at 785 g per boot in a 27 on the same 99 mm last with 75 degrees of rotation and Mondopoint sizing. The Alien 5.0 saves 175 g through a full carbon shell and cuff and costs considerably more. Racers take the 5.0; most other people are better served by the 1.0.
Shop Scarpa Alien 1.0 boots
Alien 5.0 vs. Scarpa Alien
The Scarpa Alien is the crossover build at 870 g per boot in a 27 with a 95 flex and a Carbon Grilamid LFT shell, priced for training rather than competition. The 5.0 is 260 g lighter, stiffer and fully carbon. Budget and race calendar decide it.
Shop Scarpa Alien boots
Alien 5.0 vs. Scarpa F1 XT
The Scarpa F1 XT is the touring boot of the two at 1,145 g per boot in a 27 with a 110 flex and a 100 mm last, built to ski wider skis properly. The Alien 5.0 gives up that capability for 535 g and 4 more degrees of rotation. These are different sports.
Shop Scarpa F1 XT boots
Common Questions
Who should buy the Scarpa Alien 5.0?
The Scarpa Alien 5.0 suits skimo racers and uphill athletes with narrow feet. A hand-laid carbon shell holds 610 g per boot at size 42 and 76 degrees of cuff rotation is among the largest available. The 110 flex on a 99 mm race last is the trade, so it belongs on race skis 65 to 80 mm underfoot.
What bindings work with the Scarpa Alien 5.0?
Pin/tech (low-tech) bindings only. The Vibram UFO 4.0 sole carries no ISO norm, so the Alien 5.0 is not compatible with AT/frame bindings, MNC bindings, or traditional ISO 5355 (Alpine) bindings. Scarpa lists the binding system as TLT with an Optimized Touring Pivot of 5 mm, meaning the tech toe mounts 5 mm rearward of standard. Bring that figure to whoever mounts your skis.
How is the Alien 5.0 sized?
In European whole sizes from 39 to 44, not Mondopoint. That is unusual for a ski boot and it matters: there is no half size, no direct conversion from your usual Mondo number, and the weight reference is quoted at size 42 rather than 27. Do not order this boot without a shell fit.
What is the range of motion on the Scarpa Alien 5.0?
76 degrees, the largest in the Scarpa line and among the largest of any ski boot. Scarpa does not print it in the specification block on its website but the technical manual gives 76 degrees behind the Speed Lock Lite mechanism, which also offers two forward lean positions.
Can the Scarpa Alien 5.0 be punched?
Very little. A hand-laid carbon shell does not accept the modifications a Grilamid shell does, and attempting them risks damaging the layup. Fit work goes through the SCARPA Race 4.0 SL liner and a footbed instead, which is why the shell fit matters so much on this boot.
How does the Alien 5.0 differ from the Alien 1.0?
The 5.0 uses a hand-laid carbon shell and cuff where the 1.0 uses carbon-reinforced Grilamid, which saves 175 g per boot. Rotation goes from 75 to 76 degrees and the Optimized Touring Pivot changes from 7 mm to 5 mm. The 1.0 is Mondopoint sized; the 5.0 is European. Same 99 mm last.
Is the Alien 5.0 skiable outside racing?
It can be skied, but honestly it is the wrong tool for most days. A 110 flex on a fully carbon race shell is unforgiving, the fit is narrow, and there is almost no ability to modify it. Skiers who want race weight for general ski mountaineering should look at the Alien or the Alien 1.0.
Our Verdict
The Scarpa Alien 5.0 is a competition boot and it does not pretend otherwise. A hand-laid carbon shell and cuff reach 610 g per boot at size 42, the Dyneema cord and BOA close in one action, and 76 degrees of cuff rotation is the largest figure in the line. What you accept is a 110 flex on an unforgiving carbon shell, a 99 mm race last, European whole sizes only from 39 to 44, almost no punchability, and a Vibram UFO 4.0 sole that runs pin bindings and nothing else. For racers that is the correct set of compromises; for everyone else the Alien or Alien 1.0 is the better boot.
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