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HJC R-PHA 31 Jet Helmet - kouv mc-21sf
(Product No.: BB-107H39-0.26)
RPHA 31 jet motorbike helmet (ECE 22.06 test standard)
New helmet shell materials with carbon aramid fibers, carbon fibers, glass fibers, organic nonwovens and natural flax fibers, as well as multi-density EPS for improved impact resistance and maximum protection. The aerodynamics, ventilation and rolling noise of the R-PHA 31 have been tested and optimized in wind tunnels.
Visor with extractable wind deflector at the bottom and new locking system that further contributes to noise reduction. An anti-fog pinlock is included.
Integrated sun visor with anti-fog coating. The new mechanism moves the sun visor forward by a choice of 5 mm or 10 mm, so it can be optimally adapted to your needs.
The inner lining has been adapted for spectacle wearers. The 3D-moulded lining and cheek pads are made of antibacterial material and are replaceable and washable. Reflective strips on the underside provide added safety.
Prepared for 2nd generation HJC SMART communication systems (HJC 50B and 21B), which can be integrated into the helmet.
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HJC Size Chart
HJC offers motorcycle helmets and bicycle helmets with partly different size ranges. The categories are therefore listed separately. Individual models may differ from the general reference chart; product-specific sizing always takes priority.
Motorcycle helmets – general HJC reference chart
Measure the head circumference with a flexible measuring tape around the head. For motorcycle helmets, HJC recommends measuring approximately 2.5 cm above the eyebrows.
| Size | Head circumference (cm) | Hat size | Head circumference (inches) |
|---|---|---|---|
| 3XS* | 50–51 | 6 1/4 – 6 3/8 | 19 3/4 – 20 1/8 |
| 2XS | 52–53 | 6 1/2 – 6 5/8 | 20 1/2 – 20 7/8 |
| XS | 54–55 | 6 3/4 – 6 7/8 | 21 1/4 – 21 5/8 |
| S | 55–56 | 6 7/8 – 7 | 21 5/8 – 22 |
| M | 57–58 | 7 1/8 – 7 1/4 | 22 3/8 – 22 7/8 |
| L | 58–59 | 7 1/4 – 7 3/8 | 22 7/8 – 23 1/4 |
| XL | 60–61 | 7 1/2 – 7 5/8 | 23 5/8 – 24 |
| 2XL | 62–63 | 7 3/4 – 7 7/8 | 24 3/8 – 24 3/4 |
| 3XL | 64–65 | 8 – 8 1/8 | 25 1/8 – 25 1/2 |
| 4XL | 66–67 | 8 1/4 – 8 3/8 | 26 – 26 3/8 |
| 5XL | 68–69 | 8 1/2 – 8 5/8 | 26 3/4 – 27 1/8 |
* According to HJC, 3XS is available for the C10 as a youth size.
HJC Y10 – youth sizes
| Size | Head circumference (cm) |
|---|---|
| YS | 48–49 |
| YM | 50–51 |
| YL | 52–53 |
Bicycle helmets – model-specific sizing
HJC Sports size ranges vary between certain model generations, especially for size L. The official model-specific measurements are therefore listed separately.
| Model | S – head circumference (cm) | M – head circumference (cm) | L – head circumference (cm) |
|---|---|---|---|
| Atara | 51–56 | 55–59 | 58–61 |
| Bellus | 51–56 | 55–59 | 58–61 |
| Bellus 2 | 51–56 | 55–59 | 58–63 |
| Calido | 51–56 | 55–59 | 58–63 |
| Coban | 51–56 | 55–59 | 58–63 |
| Crosser | 51–56 | 55–59 | 58–63 |
| Furion 2.0 | 51–56 | 55–59 | 58–61 |
| Furion 3 | 51–56 | 55–59 | 58–63 |
| Gleo (Kinder / Kids) | 49–55 | – | – |
| Ibex 2.0 | 51–56 | 55–59 | 58–61 |
| Ibex 3 | 51–56 | 55–59 | 58–63 |
| Route | 51–56 | 55–59 | 58–63 |
| Valeco | 51–56 | 55–59 | 58–63 |
| Valeco 2 | 51–56 | 55–59 | 58–61 |
Safety note: A size chart is a reference only. A helmet must fit firmly and evenly around the head, must not move out of position and should not create problematic pressure points. HJC warns that wearing the wrong helmet size can increase the risk of injury. Always try the helmet on and follow the product-specific fitting and safety instructions.
Updated: 11 August 2026. Basis: official HJC Europe motorcycle helmet size chart and proper-fit guidance, plus official HJC Sports product pages for the bicycle helmet models listed above.