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AGV K4 EVO Diapason Helmet
  • AGV K4 EVO Diapason Helmet - White/Black/Red
  • AGV K4 EVO Diapason Helmet - White/Black/Red
  • AGV K4 EVO Diapason Helmet - White/Black/Red
  • AGV K4 EVO Diapason Helmet - White/Black/Blue
  • AGV K4 EVO Diapason Helmet - White/Black/Blue

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Video Reviews (3)

AGV K4 EVO Diapason Helmet Videos

AGV K4 EVO Diapason Helmet

The AGV K4 EVO is the most balanced and versatile helmet in the AGV range. Performs great on sportbikes or scooters, and everything in between. Improvements in weight and comfort, the K4 EVO represents the ideal solution for those who want an attractive, safe, comfortable helmet with an excellent price/quality ratio. The design of the AGV K4 EVO reflects that of the K4, the model it replaces in the range. A design distinguished by the front air vents, the chin strap, the lateral lines and the spoiler, creating an immediate family feeling with other products in the recent AGV range.


  • Shell:  Fiberglass ACF (Advanced Composite Fiber)
  • Number of shells:  2 shell sizes
  • Ventilation System:  Front air intakes and rear extractors
  • Internal padding:  Removable and washable (excluding neckroll)
  • Internal Padding:  New 3D construction for richer and more stylish padding
  • Fabrics:  Dry-Comfort fabric with sanitizing treatment and new skin-friendly fabric, reduces skin irritation
  • Face Shield:  Clear, anti-scratch and anti-fog polycarbonate Street 8 visor
  • Shield Mechanism:  XQRS (Extra Quick Release System) for shield replacement without tools in seconds
  • Safety Certification:  ECE22.05 Certified
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AGV K4 EVO Diapason Helmet 4.4 5 71 71
My Last AGV I really wanted to love this helmet: great visibility, good airflow, BT ready and it does look nice but construction was a letdown. I found the following: 1. The padded liner is very cheaply made. The pad at the forehead will not stay in place allowing the sharp ridge of EPS to contact my forehead. (see picture) 2. Airflow is not as good as the Horizon. 3. Not related to quality but this helmet is more round then the Horizon. Ultimately I had to swallow my investment because I will not wear a helmet with liner defects. Even though I love AGV for its visibility and weight, this is my second and last AGV. Both suffered from liner issues and that is where my head lives. August 3, 2015
Decent helmet for the price Been wearing one of these for almost a year now - it's a good helmet but IMO it's quite loud, even with all vents closed, and there's some quality/durability issues that could be addressed. The good: - fits well - I typically wear a large helmet, I bought a large, no complaints. - Vents move enough air to keep from fogging if you're going more than 30 mph, even in actual fog. I commute 25 miles in the Portland area, 20 or so of which are on the highway through the valleys west of town, where it gets VERY foggy sometimes. Never had a problem with the visor fogging, just water condensing on the outside - Visor is easy to swap out - pads and liner are easy to remove for cleaning The bad: - Noisy. I don't have much experience with other motorcycle helmets but I always wear ear plugs in this thing regardless of what speed I'm going to go, and I'm not on a loud bike at all - it's the wind that bothers me. - Visor mounting system is fairly low quality. The visor mounting/ratcheting system is essentially two pieces - one piece that it actually rotates on, and one piece that clips in to a small channel that has grooves in it for the ratcheting action. This smaller piece that does the ratcheting has gotten worn from flipping the visor up and down enough that it doesn't stay in its groove anymore unless I move the visor very deliberately - no more whipping it up and down willy nilly or that piece won't stay in its channel and the visor won't seal until I push that part back into its channel. Easy to do while riding but it is annoying. - The plastic doohickey on the back that forms the point and houses the rear vents is VERY EASY to break. The helmet fell off my foot pegs once and landed directly on that - it cracked in two places. The little tabs that hold it onto the helmet also have worn down a lot (for no apparent reason, I never remove it) and at some point I'm assuming the whole thing will fall off, leaving me with an awkward looking helmet. I'd say it's a quality helmet but the visor ratcheting system and the rear vent cover leave a bit to be desired. For the money, however, it'll last you if you take care of it, and the visor can easily be fixed by replacing it. Not so sure about the rear vent cover. May 7, 2015
Dude. Sweet Light weight, decent airflow, very low profile helmet. Very quiet when your face is level. Agv's site says this is a sport touring helmet and the aerodynamics agrees. When you tuck the rear spoiler/vents work well. Errs slightly round in shape, but fits me very well now that it is broken in. May 4, 2015
Awesome I love this helmet. It's light wight, stylish and comfortable. For the it's not a bad deal at all. Thinking about getting another one my self. May 3, 2015
Saved my life I wrecked in this helmet face first going 60 mph. (was hit by a car) This helmet saved my life. The ECE certification is very similar to the snell cert and is the most common internationally. This standard is used in MotoGP. Not only did this helmet save my life, but it's comfortable, quiet, and light. For the price, I think this helmet is the best in its' class. Highly recommended. Just bought another. March 18, 2015
Great Helmet I've been wearing this helmet for a year and I love it. Fit is great and I love the red arrow graphics. Fit and finish has the look and feel of quality in materials and design. I bought mine in the philly store. The sales staff are all friendly and a pleasure to deal with. February 19, 2015
Great value Great lightweight and stylish helmet. Shape of the cheekpads, enable you to install intercom/speakers without an issue. I love the graphics and the shape of AGV helmets. Highly recommended if their shell fits your head shape. September 15, 2014
Could be better Air flow is minimal - only a couple places you can adjust to add or reduce air flow and they dont regulate a large enough flow of air (two above the forehead and one at mouth level but they;re small). Helmet whistles a little once you get to about 35mph matte black helmet scratches very easily so be careful if that's your selection August 12, 2014
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AGV K4 EVO Diapason Helmet
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Helmet Sizing

Size Hat Size Measurement (in)  Measurement (cm)
XS 6 5/8 - 6 3/4 20 7/8 - 21 1/4  53-54
SM 6 7/8 - 7 21 5/8 - 22  55-56
MD 7 1/8 - 7 1/4 22 3/8 - 22 3/4  57-58
LG 7 3/8 - 7 1/2 23 1/8 - 23 1/2  59-60
XL 7 5/8 - 7 3/4 24 - 24 3/8  61-62
2XL 7 7/8 - 8 24 3/4 - 25 1/8  63-64
3XL n/a 25 1/2 - 26 65-66

Sizing information is provided by the manufacturer and does not guarantee a perfect fit.

Click here to see the full AGV Helmets Size Chart
Product Style RevZilla Item # Manufacturer Product # Availability
White/Black/Red / LG 918219 0031O2C0-013-L Out of Stock
White/Black/Red / MD 918218 0031O2C0-013-M Out of Stock
White/Black/Red / SM 918217 0031O2C0-013-S In Stock: Ships within 24 hours
White/Black/Red / XL 918220 0031O2C0-013-XL Out of Stock
White/Black/Red / XS 918216 0031O2C0-013-XS Out of Stock
White/Black/Red / 2XL 918221 0031O2C0-013-XXL Available: Requires 3-5 business days processing time prior to shipment.
White/Black/Blue / LG 918225 0031O2C0-014-L In Stock: Ships within 24 hours
White/Black/Blue / MD 918224 0031O2C0-014-M Available: Requires 3-5 business days processing time prior to shipment.
White/Black/Blue / SM 918223 0031O2C0-014-S Available: Requires 3-5 business days processing time prior to shipment.
White/Black/Blue / XL 918226 0031O2C0-014-XL Out of Stock
White/Black/Blue / XS 918222 0031O2C0-014-XS Out of Stock
White/Black/Blue / 2XL 918227 0031O2C0-014-XXL Out of Stock