HJC RPHA 1 SPIES STAR MC-21
The RPHA 1 is HJC's grand prix helmet — developed with their MotoGP riders and homologated to FIM's FRHPhe-01 racing standard on top of DOT. The P.I.M. Plus shell layers... Read More
The RPHA 1 is HJC's grand prix helmet — developed with their MotoGP riders and homologated to FIM's FRHPhe-01 racing standard on top of DOT. The P.I.M. Plus shell layers carbon, aramid, and hybrid fibers into the stiffest, lightest structure HJC builds.
The flat HJ-35 race shield ships with a Pinlock insert and tear-off posts, an extended racing spoiler is in the box, and emergency-release cheek pads complete the race spec.
Features
- DOT FMVSS 218 and FIM FRHPhe-01 homologated
- P.I.M. Plus carbon/aramid hybrid shell
- HJ-35 flat race shield with Pinlock insert and tear-off posts included
- Extended racing spoiler included
- Emergency-release cheek pads
- Double-D ring chinstrap
Specs
- Certification: DOT FMVSS 218, FIM FRHPhe-01
- Shell: P.I.M. Plus carbon hybrid
- Shield: HJ-35 race flat; Pinlock + tear-offs included
How to measure
Wrap a cloth tape measure horizontally around the fullest part of your head, about 1 inch (2.5 cm) above the eyebrows. Repeat a few times and use the largest measurement. The chart is a starting point — always try the helmet on for final fit.
HJC size chart
| Size | Head circumference (cm) | Head circumference (inches) | Hat size |
|---|---|---|---|
| 3XS | 50-51 | 19 3/4 - 20 1/8 | 6 1/4 - 6 3/8 |
| 2XS | 52-53 | 20 1/2 - 20 7/8 | 6 1/2 - 6 5/8 |
| XS | 54-55 | 21 1/4 - 21 5/8 | 6 3/4 - 6 7/8 |
| S | 55-56 | 21 5/8 - 22 | 6 7/8 - 7 |
| M | 57-58 | 22 3/8 - 22 7/8 | 7 1/8 - 7 1/4 |
| L | 58-59 | 22 7/8 - 23 1/4 | 7 1/4 - 7 3/8 |
| XL | 60-61 | 23 5/8 - 24 | 7 1/2 - 7 5/8 |
| 2XL | 62-63 | 24 3/8 - 24 3/4 | 7 3/4 - 7 7/8 |
| 3XL | 64-65 | 25 1/8 - 25 1/2 | 8 - 8 1/8 |
| 4XL | 66-67 | 26 - 26 3/8 | 8 1/4 - 8 3/8 |
| 5XL | 68-69 | 26 3/4 - 27 1/8 | 8 1/2 - 8 5/8 |
Youth sizes
| Size | Head circumference (cm) | Head circumference (inches) |
|---|---|---|
| YS | 48-49 | 18 7/8 - 19 1/4 |
| YM | 50-51 | 19 5/8 - 20 1/8 |
| YL | 52-53 | 20 1/2 - 20 7/8 |
One official HJC chart covers all models (full-face, modular, open-face, half); size availability varies per model. cm values are canonical (verified on both official US and EU HJC sites); inch values follow the mathematically consistent EU print where the US page conflicts with its own cm column (M and L rows). Note: many retailers still publish HJC's LEGACY chart (XS 53-54 … 3XL 65-66), which disagrees with the current official chart — do not mix them. Youth chart is the official Y10 chart (EU site).
Manufacturer sizing data · verified July 8, 2026
