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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.

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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.