Helmets · fit and replacement

Measure, fit and replace your helmet

An ISI-marked helmet is the legal starting point. Whether it protects you on the day depends on three things you control: the size, how it sits and fastens, and whether it is still in good enough condition to absorb another blow.

Measure your head

Wrap a soft tape measure, or a piece of string you then lay against a ruler, around your head just above the eyebrows and the tops of the ears, the band a helmet covers. Keep it level and snug, not tight. Measure two or three times and use the largest reading as your starting size; the fit test below has the final say.

Source: Helmet sizing chart (Studds Accessories Ltd (helmet manufacturer)), checked 26 October 2026.

Size letters are not a shared standard. The Snell Memorial Foundation describes a helmet's size label as a general suggestion and notes sizes differ between makers. For example, one Indian maker's chart labels 57 to 58 cm as M; another brand's M may start or end elsewhere. Always compare your number with the chart for the helmet you are trying on, and if you sit on the boundary between two sizes, try both.

Sources: Choosing the Right Helmet (Snell Memorial Foundation); Helmet sizing chart (Studds Accessories Ltd (helmet manufacturer)), checked 26 October 2026.

The fit test in the shop

Head shapes vary as much as sizes, so try helmets on before you buy, from more than one maker if you can. With the helmet on and the strap fastened:

1. Snug all round. The helmet should feel snug around the whole crown, with the cheek pads touching your cheeks and no gaps.
2. Strap test. Tighten the chin strap until no more than two fingers fit between the strap and your chin.
3. Push and pull. Try to pull the back of the helmet forward, then push the brow back. If it slips either way, it is too large.
4. Shake test. Turn and nod your head. The helmet should move with your head, not on it.
5. Wear it for five to ten minutes. Keep it on for at least five to ten minutes before you buy, to see whether any spot becomes uncomfortable. On some models the cheek pads can be swapped for comfort.

Sources: Frequently Asked Questions (Snell Memorial Foundation); Choosing the Right Helmet (Snell Memorial Foundation); Helmet sizing chart (Studds Accessories Ltd (helmet manufacturer)), checked 26 October 2026.

A new helmet should fit very snugly, Snell advises. Comfort padding compresses with use, so a helmet that feels comfortable but loose in the shop will only get looser.

Source: Frequently Asked Questions (Snell Memorial Foundation), checked 26 October 2026.

Our suggestion, not from the sources above: if you ride in glasses, wear them for the fit test. The arms should slide in without pressing on your temples.

Visors

• Check the visor is clean and in good condition before each ride. Scratched or poorly fitting eye protection reduces what you can see, especially in bright sunshine and in the dark.
• Visors marked for daytime use only are not suitable after dark. If your helmet came with a tinted visor, carry a clear one for evening rides.
• Clean visors with lukewarm water and mild soap and a soft cloth. Do not use organic solvents, metal polish or similar products on a visor.

Sources: The Highway Code — Rules for motorcyclists (83 to 88) (Department for Transport, GOV.UK); Care & Maintenance (Studds Accessories Ltd (helmet manufacturer)), checked 26 October 2026.

Cleaning and storage

• Follow your helmet maker's instructions first.
• Clean inner pads with mild soap and water only; Snell advises never using chemical cleaning products inside or outside the helmet.
• Keep petrol and solvents off the shell, and do not paint it or add stickers; at least one maker warns these can damage the helmet in ways you cannot see.
• Let a wet helmet dry at room temperature, away from direct sun and heat sources.
• Do not hang the helmet on a mirror or handlebar, and keep it away from hot silencers. Hard edges can dent the inner foam.

Sources: Frequently Asked Questions (Snell Memorial Foundation); Care & Maintenance (Studds Accessories Ltd (helmet manufacturer)), checked 26 October 2026.

When to replace a helmet

Published guidance is consistent on crashes and differs slightly on age:

Sources: Frequently Asked Questions (Snell Memorial Foundation); FAQ (Studds Accessories Ltd (helmet manufacturer)), checked 26 October 2026.

Our reading of both: replace after any crash, even if it looks fine. After a drop, inspect it and replace it if in doubt. Plan for replacement somewhere between three and five years of regular use, and sooner if the fit has loosened, the padding has flattened, the strap or buckle is worn, or the shell is cracked. Your helmet maker's instructions take precedence.