What is the benefit of smaller shell size in motorsport helmets

The high-speed nature of motorsport throws up all kinds of challenges to a driver, but there are three main issues that generally affect drivers and helmets. 
Shell sizes. 

Small car cockpits with rollbars make cars feel a little claustrophobic, if you race in a Ferrari Challenge or GT3 race car with a low roof height then a small shell size can make a big difference in car. Roof height can be an issue for drivers that want to sit up in cars, and small doorways make driver changes difficult.

Wind effect 

Open top race cars can cause some wind issues on a driver’s helmet, aerodynamic devices can control buffeting, but a small shell size of a helmet can decrease the affect the wind has on it

G-Force 

High speed cornering adds another issue, racing cars produce much higher G-forces with F1 cars generating the most and can be around 5G in force. The effect of G-force basically increases the feel of weight on a helmet, a helmet weighing 1.5kg at 2 G has the feel of 3kg, 3 G feels like 4.5kg on your neck and so on. 

As you can imagine with every corner and every braking session during a race will dramatically affect the endurance of a driver’s neck muscles, and once your neck starts aching your level of concentration drops together with your driving performance.

So, how do you counteract these issues. The key is to make sure that your helmet has the smallest overall shell size, and that the helmet is the lightest weight available for the safety standards that is required for your racing. 

Stilo Helmet Design

Stilo is very aware of all these issues, which is why they have developed an in between sizes throughout their complete range of racing, rally and kart helmets. These helmets having smaller dimensions on the shell and different interiors. These sizes work as follows: 

ST6 CMR Kart Helmets

•    2 Shell Sizes available in the range
•    Extra Small Shell (new for 2026) – Sizes XXS 53, XS 54, S 55 and M 56. 
•    Small Shell – Sizes M 57 and L 59. 

Size M 56 having an extra thin liner to save the driver going to the next shell size and saving around 100 grams in weight.

ST6 Racing Helmets

•    5 Shell Sizes available
•    Extra Small Shell (ST6 Zero helmet range only) – Sizes XS 54, S 55 and M 56
•    Small Shell (All other ST6 models) - Size XS 54 and S 55
•    Medium Shell – Sizes M 57 and L 58
•    Large Shell – L 59 and XL 61
•    XL Shell – Sizes XXL 63 and XXXL 64

Sizes M 56 and L58 have extra thin liners to save going to the larger shell size, but the weight saving here will vary depending on the model and construction you choose. This will save between 70 to 100 grams in each model and construction available. 

Venti4 WRC and Venti4 Trophy Helmets

Rallying does not have all the same issues as in racing, but the weight benefit can really help in rallying. Stilo have produced some shell sizes to benefit both driver and co-driver. 

•    3 shell sizes available
•    Small Shell – Sizes XS 54, S 55, M 57 and L58
•    Medium Shell – Sizes L 59 and XL 61
•    Large Shell – Sizes XXL 63 and XXXL 64

For open face rally helmets the L 58 keeps you in the small shell size with weights savings of 40 grams in carbon models and up to 130 grams in composite versions, but all benefiting from the same smaller shell dimensions.

Conclusion

Shell size and helmet weights are critical and must not be overlooked if you are looking to improve your performance on track or rally stages. The Zero range from

Stilo offers the lightest helmets, to the highest safety standard and with a shell size selection that is unmatched in other brands. 

No matter what construction you choose, there is a helmet option that could benefit you. If you would like more information, or you would like a get a bespoke helmet fitting then call us at Nicky Grist Motorsports. We would be delighted to help you.