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HJC i 20 Jet Helmet - thorn mc5sf
(Product No.: BB-107H15-0.55)
Jet helmet i20 (ECE standard 22.06)
This Street Fighter look jet helmet has something that other jet helmets don't have: a removable chin piece. The chin piece is not homologated to protect in collisions, but in cold and wet weather it makes all the difference.
The visor is anti-fog coated, protecting the eyes from insects as well as the blinding sun, and can be replaced with a clear visor during night times (included).
The advanced polycarbonate composite shell is lightweight and provides a great fit, with a 3-shell split from size XS to 2XL.
This helmet is also suitable for the SMART HJC Bluetooth systems (10B and 20B).
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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.