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Giro Trinity Helmet
Sale $27.96$39.95 30% Off

Item # GIR008B

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Item # GIR008B


Holey trinity.

When you break it down, a cycling helmet is actually a pretty simple affair. Behind the acronyms and camel-case, proprietary technologies are three basic elements: a polycarbonate shell, an EPS foam body, and an adjustable retention system. The Giro Trinity Helmet incorporates all three, with the addition of a holey, ventilated design, making it the Alpha of cycling helmets. Omega can keep its acronyms.

The shell and EPS body are fused via Giro's application of In-Mold technology. This makes for better impact-absorption and more structural integrity, while the addition of rear-oriented reflective elements may keep you from needing to rely on those properties. In the event of a tumble, the Acu Dial fit system means your helmet will be held securely in place to provide the highest level of protection possible.

  • In-Mold Technology with EPS foam
  • 22 vents
  • Acu Dial fit system

Tech Specs

Shell Material:
Impact Foam:
EPS foam
22 vents
Fit Adjustment:
Acu Dial
Recommended Use:
road cycling
Manufacturer Warranty:
1 year

Size Chart


Adult Cycling Helmets
 SS/MMM/LLXLAdult UniversalWomen's Universal
Head Circumference 20 - 21.75in
(51 - 55cm)
20 - 22.5in
(51 - 57cm)
21.75 - 23.25in
(55 - 59cm)
21.75 - 24in
(55 - 61cm)
23.25 - 24.75in
(59 - 63cm)
24 - 25.55in
(61 - 65cm)
21.25 - 24in
(54 - 61cm)
19.75 - 22.5in
(50 - 57cm)
Head Circumference 20 - 20.75in
(51 - 53cm)
21.25 - 22in
(54 - 56cm)
22.5 - 23.25in
(57 - 59cm)
23.5 - 24.25in
(60 - 62cm)
How to Measure:
For best results, use a tape measure to measure around your head where your hat would fit comfortably.

Reviews & Community


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Best helmet I've used so far!

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

The helmets adjustment knob has a very large range of adjustment so it's easy to lend out or people or just adjust on the go. The ventilation is fantastic and even on long trips my head stays cool. Overall the helmet is extremely comfortable and I am definitely going to purchase it again once I need a new helmet.

Love this helmet, fits well.

    I got this helmet for my 9 and 10 year old kids as they were outgrowing their Giro youth helmets. This fits them perfectly, the adjusting mechanism was easy to use, and the style looks great on too. Got the black with white, the white with silver also looks nice. The helmet also fits well if you need an Asian Fit helmet. We also tried a higher priced helmet and the Giro Trinity still came out the winner by far!

    Great helmet and fits well

    • Familiarity: I've used it several times

    I got this helmet for my two kids, 9 and 10 yo as they were starting to outgrow their Giro youth helmets. The Trinity fit both of them well, very comfortable and looked great too. One of my kids has a slightly flat head and usually needs an Asian Fit snow helmet, since I couldn't find an Asian Fit bike helmet, we tried this one and this was perfect on her as well! The colours are exactly as pictured, we love both the black with white, and the white with silver.

    picture is deceiving

      Purchased the white w/ grey flowers style, as the picture made it out to look mostly white. It's definitely a silver-on-silver style. Will be returning for a true white helmet.

      Good budget-priced helmet

      • Familiarity: I've used it several times

      When you break it down to brass tacks, the primary purpose of a helmet is to protect your melon. Sure, there are helmets that are more expensive, ligher, vent better and look more badass, but if your main care is shielding the ol' noggin, the Giro Trinity helmet does that very well, and at a reasonable price. The Acu Dial fit system adjusts to fit a wide range of head sizes, and the vents do a reasonably good job at promoting airflow to keep you cool.

      Poor finish

      • Familiarity: I returned this product before using it

      The price, fit, weight, and hi-viz were great. The finish was poor. I'm sure it didn't affect protection, but even at a low price point I expect better. This was my second attempt at ordering a Trinity and they were both of similar quality. The vent holes looked like they were whittled out with a pocket knife.

      Giro Trinity Helmet

      • Familiarity: I've used it several times

      Helment is very light and comfortable. I recommend this purchase to anyone who is looking for great helmet.