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Kask Protone Helmet


Item # KSK000I

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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 odor-resistant, removable, and contribute to the comfortable, personalized fit of the floating Octo Fit cradle and corresponding ECO Chinstrap.

  • Top your head with the helmet that tops Tour podiums
  • In-Mold shell increases structural integrity
  • Aerodynamically verified in ye olde wind tunnel
  • Adjustable cradle keeps your tactical muscle secure
  • Ventilation channels to encourage air flow and keep you dry
  • Anti-odor padding will fend off stink for way longer than 21 days

Tech Specs

Shell Material:
Impact Foam:
EPS foam
Fit Adjustment:
Octo Fit
CE EN 1078, CPSC 1203, AS/NZS 2063
Recommended Use:
road, cyclocross
Manufacturer Warranty:
limited lifetime



Claimed Weight

Claimed weights are provided by the vendor.

Have questions? Chat with a Gearhead

[size medium] 230 g, [size large] 250 g

Size Chart


Vertigo, K50 EVO, K50 MTB
Head Circumference

18.9 - 22.8in

(48 - 58cm)

23.2 - 24.4in

(59 - 62cm)

K10 MTB, K31 Crono, K10 Race
 One Size
Head Circumference

20.9 - 24in

(53 - 61cm)

How to Measure:
Measure around your head where your hat would fit comfortably.

Reviews & Community


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Saved my life

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

First off, I loved the helmet...light, cool, and looks good...sizing and fit was perfect. Then, it saved my life on a crash...took a good beating off the roadway and kept the noggin in tact...not even a concussion....can’t say the same for the skin on my shoulder and hip...will be ordering another to get back out on there!

Saved my life

Weight significantly higher than claimed

  • Familiarity: I returned this product before using it
  • Fit: True to size

I am a multi-decade avid cyclist and a bit of a weight weenie. Been waiting for the Protone to show up in small ever since it came on the market. I ride in the Southeast hot and humid. Like the concept I could get a light helmet with decent ventilation and Aero properties to boot. Also loved the aesthetics matching my Dogma and kit nicely. Claimed weight on Kask site is 215gr and on CC site at 230gr in medium. Turns out when I received my small it weighed in on my Feedback scale at 278gr. I thought the scale must be broken. It also felt heavy when I put it on versus my current S-works helmet. Decided to return the Protone (love how easy CC makes this process) and buy the Giro Aeon. Aeon claimed weight is 211gr and came in on my scale at 213gr. I am usually skeptical of claimed weights but, Kask has taken it to a new level. Very disappointing.

Thanks for the review Kevin! Glad that you ended up with the right helmet in the end.

Avg. ride time: 2h 13m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

It Fits!

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

I've sold these helmets for years now and I rarely come across a rider who the Protone will not fit. When you pay for a $299 helmet you're not necessarily getting any greater safety benefits, you're paying for the fit. Kask delivers a strong all-around helmet - perfect for racing, cruising and everything in between. Aero enough for the budget-conscious triathlete and breathable enough for the climber pushing maximum effort.

I wear a 59-62cm (LG) in just about every helmet and the Protone is no exception.

Wide heads rejoice!

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

This is the only helmet that fits my wide head. I've tried on countless helmets, but nothing fits like the Protone. It's an expensive helmet, but not having to experience pressure buildup around the temple is worth every penny. Plus, I'd say it's one of the best looking helmets out there. What's not to like?

El mejor y mas bonito casco del momento

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

Super comodo, super chevere, muy ajustable y super fashion, con Oakleys Jawbreakers

Avg. ride time: 9h 49m per week
  • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

Pro-level Brain Bucket.

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

The overall quality of this Kask helmets is great. It is light, vents well, and looks fantastic.

The fit adjustment offers a large range of adjustments the leather chin strap is super comfortable. I use this helmet for road and CX.

Looks and Safety

  • Familiarity: I've used it several times
  • Fit: True to size
  • Size Bought: small/medium

The moment you pull this helmet out of the box, you see and feel the quality that Kask has put into it. The overall quality is superb, and the weight is quite minimal.

I primarily use this for the road, and it has worked out great! I decided to try it on a recent mountain bike ride and it did well on the flats and climbs, but going down hill something changed and I had this pain digging in on the back off my head where it grips and keeps the helmet in position. I eventually had to stop and see what was going on, and couldn't do anything other then open up the dial for the remainder of the descent. If you're buying this for the road it performed flawlessly, and on the mountain, I will actually stick with the helmet that has been my normal go-to.

Questions about Kask or other helmets, please reach out.

Looks and Safety

Literally, The best

    Purchased for a friend, here's what he had to say about this helmet!
    Best helmet I have ever owned. I’ve ridden Laser, Giro, and others, and this thing is by far the best. The style is impeccable, and distinctly “Euro.” From there, the venting is great. My favorite feature is the leather chin strap, which is super super comfortable on a long ride, particularly compared to normal nylon that ends up caked in salt/sweat and chaffing. One note: I bought the normal black (glossy), but after seeing some matte black Kasks on the road I would probably have gone with the matte if I could do it again.

    Safest, Most Comfortable Helmet Around

    • Familiarity: I've put it through the wringer

    This helmet all but saved my life during a crash this past weekend. I took a spill at just shy of 35mph going downhill on my TT bike and knocked my head pretty hard on the pavement.

    Aside from being very fortunate to only have road rash and no breaks, this helmet prevented any head injury whatsoever - no cracks, concussions, scratches, etc.

    I can't guarantee no one would sustain further injuries but I can't say enough about my confidence in the safety of this helmet.

    It's wicked comfortable to boot! Super adjustable and the leather chin strap is a lot more comfortable than you may think.

    Even if there is no sale on the helmet, $300 is a small price to pay for the safety and comfort of this helmet.

    Poor Build Quality

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

    When I received it in March 2017 I loved it. It fit well, it vented well and it was really light! All essential qualities for long rides in hot and humid Singapore.

    What I didn't like was realizing that those soft inserts of those two rear paddles/supports (the ones where the straps go through) at the back of your head had started to fall out! C'mon, this is an expensive piece of kit and to have bits falling off? Not cool.

    Needless to say this is the last time I am buying a KASK.

    Avg. ride time: 1h 34m per week
    • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

    Great aero at angles

    • Familiarity: I've used it several times

    Great fit after a little breakin (pads felt a little weird at first). At speed I was pleasantly surprised at this feeling dramatically more aero at angles than any other helmet I've used (Giro and Bell). In other words, you can turn your head left/right and not feel wind tug.

    I've used a number of helmets over the years, and so far this is my favorite by far.


      Contrary to numerous reviews that I have seen and which I based my purchase, this helmet is not low profile, streamlined (sic), etc. I purchased large (59 cm) because I was at the very high end of medium. The helmet adjusted just fine but the size of the helmet made me feel as if I had a 2-3 gallon bucket on my head. I have Garneau and Giro helmets that I compared to the Protone . They are considerably more 'sleek' and have ample protection.

      Great helmet

      • Fit: True to size

      It's got a great look, aero, and still well ventilated. I think the front padding is lacking, as compared to the Kask Mojito. Only caveat is that if you have glasses with long arms, then it may run into the helmet and not site well. I have the Oakley jawbreakers with the shorter arms and don't have this problem, but some of my buddies who have the same helmet have complained about this.

      Glasses upside down is typically the way you're suppose to put them. Most helmets are designed that way..

      This helmet is everything

      • Familiarity: I've put it through the wringer

      All aspects of this helmet are on point. The price point matches the quality you'll be receiving. So so light and fits great. Little details like the Coolmax in it make all the difference.

      Fantastic Cycling Helmet

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

      I just received my Protone helmet and took it on a 60 mile madden voyage. I decided to transition from Laser Helmets to Kask based on reviews. I am totally glad that I made the jump. The Protone is by far the most comfortable fit I have ever had, and with all the different adjustments by far the most stable platform. I am glad I made this transition and totally recommend their helmets.

      Avg. ride time: 6h 15m per week
      • Average ride time is based on Strava activity over the last 3 months. Give your reviews credibility by connecting your account.

      Cool and Aero

      • Fit: True to size
      • Size Bought: Medium

      The Protone is a do it all helmet, it is both aero, and provides adequate cooling compared to some other "aero" only helmets. Wraps over, and around the head more than some other helmets, but don't even notice it is on during long days in the saddle, like it so much I have two now. The leather chin strap is a super high-end touch.

      UPDATE: Helmet is great for cooler weather conditions, but continually drips sweat directly into my sun glasses. Have been using a Halo to prevent this, but something to consider for a hot climate.

      Pretty excited about this helmet

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

      To those who felt that this helmet was heavy I feel that you are crazy. I can barely tell when I am wearing this helmet. I have worn this helmet up to 62 miles (100 km) without feeling neck pain from additional weight. The chin strap is very comfortable, as it is leather, but takes a little longer to adjust. The ONLY change I would make to this is to make the ear loops slightly longer. I just prefer them being a little more below my ears.
      The rear adjustment is great. I have worn it with my beanie on a cold ride and haven't had an issue. Even when riding unbuckled it sits well and doesn't slide around nor does it cause that headache from being too tight.

      I got the large and I wear a 7 5/8 hat if that helps any of you.

      So many PROs and no cons to the PROtone

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

      I used this helmet on an Ingamba bike tour trip and I LOVE it! It is super lightweight and comfy it felt like I was not even wearing a helmet at all. Helmet has great sunglasses holes on the top too which are perfect for the all important pre-ride cafe stops and post ride pub stops. I wear a medium in all my other helmets and a medium in this helmet fit perfectly and accommodates a cap or headband underneath for colder rides. Here's a pic of me rocking the Black Protone with a cap under it. Seriously recommend this helmet.

      So many PROs and no cons to the PROtone