Knowhow: How to wear a cycle helmet (if you choose to)

Heads don’t come in just three sizes. Adjust those straps
In short: not on the back of your head like a bonnet or with loose straps. To work as intended in a fall from your bike, a helmet needs to fit correctly, be adjusted correctly, and be worn correctly, as Dan Joyce explains

The right size

Cycle helmets generally come in only a handful of sizes: one or two children’s sizes, for example, or small, medium, and large adult sizes. Each will have a range in centimetres, showing the head circumferences it should accommodate.

Measure your head before going to the shop. Hold the tape horizontally around your head, above your ears and eyebrows. Your head is probably 50-something centimetres, with men having larger heads than women on average.

Try on helmets at the shop. The most comfortable may be a size up – or a different model entirely – because different designs suit different head shapes, some fitting rounder heads best, others longer heads.

Men’s and women’s helmets may look different (for which you can thank the brand’s marketing department) but the only real difference is that the S/M/L size bands for women’s models may be smaller. Get whichever fits best, regardless of its supposed gender. If you have a particularly large head (over 60cm), try Bontrager: its helmet sizes go up to 66cm.

Adjusting the fit

There may be a choice of foam pads to fine tune fit and comfort. Most helmets have a strap that cradles that back of the head, adjustable via a ratchet or dial. Adjust it until the helmet feels snug but not uncomfortable. Leave the chin strap undone for now.

Shake your head from side to side, like you're indicating “no”. The helmet should move with your head and not come loose. Then bend over gently so the top of your head is pointing at the floor. Even with the chinstrap undone, the helmet should be snug enough that it stays on.

How to wear it

The brim of the helmet should be no more than a couple of fingers’ width above your eyebrows. If your forehead is exposed, it’s unprotected.

Finally adjust the chin strap. The twin straps at each side should meet in a V under your earlobes. The strap under your chin should be loose enough that you can yawn comfortably but snug enough that you can get only a finger or two underneath. It may take a while to sort this out, as you faff with sliders and strap lengths. Take this time. Be aware that the straps can work loose over time, so you may need to readjust them later.


A cycling cap or a stretchy snood will fit fine under most helmets. You may need to adjust the chin strap and probably will need to adjust the rear ratchet strap.

Anything fitted to the exterior of a helmet must be able to snap free instantly in the event of a crash. Visors are designed to do this. Lights and cameras may not be. If they snag the ground or road, your head could be spun around, exacerbating (or causing) neck injuries or rotational brain injuries.

Care & replacement

The foam pads in helmets absorb sweat. Take them out and handwash them if they start to niff, or put them in a mesh bag in the washing machine. If the helmet itself gets dirty, you can handwash it tepid water. Let it dry out naturally.

Cycle helmets are designed to crumple. If you have a fall and bang it, you should replace it. Even if it’s not visibly damaged there may be hairline cracks. Some manufacturers have a crash-replacement policy; ask about this at the shop.

Even if you don’t crash your helmet it will have a limited lifespan, due to sweat, sunlight, and general wear and tear. Manufacturers suggest a use-life of three to five years – a fair guideline.