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Item # KSK000I

Protect your tactical engine.

While the cyclists at Team Sky are more renowned for their legs than their brains, the latter do occasionally play a significant role in cycling. Case in point is Stannard's surgical dismantling of an apparently invincible Ettix-Quickstep at Omloop. Given that cycling is often equal parts cunning and strength, the pros at Sky rely on Kask's Protone Helmet to keep their strategic organ in top shape so it can effectively direct their energies when frantic finales send all the blood rushing to the legs.

Tactical engines like Stannard's are protected by an in-mold construction of a polycarbonate shell bonded with an EPS foam body, all of which is built on a frame designed to let the helmet absorb impact while still maintaining enough structural integrity to see you safely through the duration of a crash.

While safety is a helmet's first (and usually last) job, there are certain benchmarks that today's industry expects top-end protectives to meet. The current frontrunner in this category is aerodynamics, and the Kask ran the Protone through the expected wind-tunnel paces in order to design a model that dodges the wind whether you're head-on in the drops or in virtually any other cycling posture imaginable.

The second consideration is cooling, and unlike many of its competitors, the Protone doesn't sacrifice ventilation for aerodynamics. In addition to the immediately obvious vents and rear exhaust port, the Protone incorporates Coolmax padding. Coolmax padding equates to more efficient moisture transfer and evaporation to complement your body's natural cooling process. They're also antibacterial, removable, and contribute to the comfortable, personalized fit of the floating Octo Fit cradle and corresponding ECO Chinstrap.

  • In-Mold Construction; polycarbonate shell over EPS
  • Coolmax padding
  • Octo Fit Cradle and adjustable chinstrap

Tech Specs

Shell Material:
Impact Foam:
EPS foam
Fit Adjustment:
Octo Fit
CE EN 1078, CPSC 1203, AS/NZS 2063
Claimed Weight:
[size medium] 230 g, [size large] 250 g
Recommended Use:
road, cyclocross
Manufacturer Warranty:
limited lifetime

Size chart


Vertigo, K50 EVO, K50 MTB
Head Circumference18.9-22.8in
K10 MTB, K31 Crono, K10 Race
One Size
Head Circumference20.9-24.0in
How to Measure:
Measure around your head where your hat would fit comfortably.

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Best Ever

  • Familiarity: I've put it through the wringer
  • Fit: True to size
  • Size Bought: Medium

This is the most comfortable, best fitting helmet I have ever bought.

Best helmet ever!

  • Familiarity: I've used it several times
  • Fit: Runs small
  • Size Bought: medium

I love this helmet! I have had a ton of different road helmets and this is by far my favorite. It is lightweight, has a classy leather strap, good color choices and overall looks super pro. I usually wear small helmets and this helmet starts at size medium, which fit me well so I think the sizing runs small. I would highly recommend this helmet for high performance road riding/ looking good at coffee shops.

Avg. ride time: 14h 35m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.


  • Familiarity: I've put it through the wringer
  • Fit: True to size

I've had good experiences with Giro and Specialized helmets but this Kask takes the cake for comfort and adjustability.

Kask Protone

    Recently switched from a Lazer helmet and so far so good. Fits well, ventilation is great...only downside is oakley frames don't fit well when put on the helmet.

    Avg. ride time: 4h 3m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Lllliiike a glove.

    • Familiarity: I've put it through the wringer
    • Fit: True to size
    • Size Bought: Large

    I've got a very narrow, but deep, head. Fit has always been a problem. I chatted online with one of Competitive Cyclist's gear experts to explain my dilemma: finding a helmet big enough for my "...virtual planetoid..." but that was also very low profile, aka not an inverted salad bowl. The gear expert recommended the Kask Protone in an instant...and even placed the order for me. I've since received the helmet, done dozens of rides and can honestly say it's the best helmet I've ever owned or tried on. For reference, I've owned a Giro Atmos and...well, I can't remember the other. As part of the shopping process, I also tried on s Giro Synthe, Lazer Z1 and a couple of Bontrager lids. The Protone is what I've been missing.
    Only complaint is that I wish helmet manufacturers would also publish EXTERNAL helmet dimensions for people like me, who are looking for the most svelte of designs...


    • Familiarity: I've used it once or twice and have initial impressions
    • Fit: True to size
    • Size Bought: Large

    I have completed about 100 miles wearing this helmet and I feel pretty confident that this is what I have been looking for. Perfect fit, perfect weight, perfect ventilation and perfect look. I'm a happy cyclist.

    Kask Protone

    • Fit: True to size
    • Size Bought: Medium

    The Kask Protone is the best cycling helmet that I’ve ever owned. Right out of the box, the Protone screams performance luxury. The packaging presents this item like a luxury gift. The helmet’s padding is reminiscent of an Italian sports car. Riding the Protone is much quieter than the Giro Aeon and the air flow cools my shoulders and back. Very easy adjustments. The leather chin strap feels luxe and I feel faster too. I especially hope that I never have to test the Protone’s impact protection. Great item
    Charles Flink
    Truth or Consequences, NM

    Aero and cool

    • Familiarity: I've used it several times
    • Fit: True to size

    Surprised by the air flow around head, great fit and sleek modern profile. Helmet is stylish and stable, aids in confidence. Am hopeful the carriage, harrness and straps, last. Quality head holder that breathes performance.

    Avg. ride time: 12h 14m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Ligth and good look

    • Familiarity: I've put it through the wringer
    • Fit: True to size
    • Size Bought: Medium

    Nice look, not hot inside the helmet

    Best I've owned to date

    • Familiarity: I've used it several times

    This review is more of a comparison to the Vertigo 2.0

    I purchased this helmet because the two Vertigo 2.0 that I had prior both failed in some way shape or form within 6 months of use.

    The Protone is lighter than the Vertigo 2. I also prefer the head adjustment retention dial better on the Protone. The one of the Protone is bracketed in with plastic framing. I had the dial pop off of my Vertigo which was one of the reasons for my latest return.

    I also prefer the cradle on the Protone as well. When you adjust it up and down it actually stays in place. Whereas the Vertigo will move freely once it's off of your head. This means once I set the cradle on the Protone it's in the same spot that I left it the last time I wore it. This is handy if you like to wear a hat under your lid or in the winter time when you need to have an extra head layer. It make it so there is one less thing you are fiddling with.

    I can't speak to aerodynamics vs. the Vertigo 2. since I'm only a commuter cyclist but hands down this is a better helmet fit and finish than the Vertigo.

    great fit for MY head

    • Familiarity: I've put it through the wringer
    • Fit: True to size
    • Size Bought: medium

    what fits me (and others) don't mean anything if it doesn't fit YOU. So let's get the fore-mentioned out of the way before you continue to read my review.
    Before getting this, I also have owned Kask Vertigo and THOUGHT it was the best until the Protone gets on my head. The fitting fits better as it sits "in" your head but not "on" your head, and that's why they look ore low-profile than some other helmets on the market.

    I got this while the website was running a special, and would love to give ALL my business to Competitive as long as they can price match.

    Unanswered Question

    On the black/lime helmet, does the lime color wrap around to the backside for rear visibility purposes?

    Great look & fit, but not optimal...

    • Familiarity: I've used it several times
    • Fit: True to size

    Very streamlined (i.e. - doesn't look like a huge bucket on the head), and generally very comfortable in how it cradles the head, etc. I also like the leather straps. My one beef is where the straps form the triangle under the ears - they are sewn in a fixed position and this is not adjustable - clear room for improvement in my opinion.

    Avg. ride time: 3h 28m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Cool look, cool head

    • Familiarity: I've put it through the wringer

    Okay so maybe the title is a little misleading. It IS a great looking helmet, and keeps your head pretty cool. But, do remember this thing is billed as one of Kask's aero helmets. With that said it ventilates extremely well, more so than the Evade I have. But it will not beat a standard ventilated helmet, like a Specialized Prevail.

    The retention system feels great, its stable, and the padding is supple and wicks well. My only gripe is the use of the stiff leather for the chin strap. I know that it's intended to be anti-microbial and prevent wear and tear with respect to use and excessive sweat, but it makes the helmet feel somewhat cumbersome and does not sit flush to your chin at all.

    With that all said, I would highly recommend this helmet for those that can afford it. 5-star product, love it.

    Best there is

    • Familiarity: I've used it several times

    I have owned many high-end helmets and this is hands-down the most comfortable well fitting helmet I have ever owned. From the eight position rear fit adjustment to the plush padding and the fantastic leather chinstrap you almost forget you're wearing this.
    I have used this helmet on 95+ degree days in high humidity and never felt hot . I definitely notice the aerodynamic drag benefits from the decreased amount of wind noise around my ears while listening to music.
    I know a bicycle helmet can be a very personal thing but I can't say enough good things about the Kask Quality and the way these helmets fit .
    Money was not an option when I purchased this lid and I don't believe that there is a better one to be found .
    Do yourself a favor and get one you won't be sorry .

    New Semi-Aero convert!

    • Familiarity: I've put it through the wringer

    I recently purchased the Protone to replace my Laser Helium. While the Helium is not the best venting helmet, the Protone vents far better. The fit is fantastic, the straps unusually comfortable and the adjustable retention system is probably the best I've used.

    I'm not a big fan of aero road helmets, but whatever amount of "aero advantage" the Protone may have seems to work. The helmet feels..."faster" with a bit less perceived drag.

    On paper and according to other reviews the Protone is a bit heavy, but honestly I have not noticed. The first real test was a 7 hour day in 90+degree temps and with a light skull cap it was plenty comfortable.

    Love it!