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Our Thoughts on Motorcycle Crash Helmet Shell Sizes

By Designer Helmets on 23rd January 2017
A lot is made these days about the number of sizes a model of motorcycle helmet shell comes in. But what does it mean and what difference does it make?
We have to be honest, it was only after actually working closely with helmets that we actually thought about what it means, and we would anticipate there are a large number of motorcyclists who are not in the slightest bit bothered. But for those who are, the shell size is exactly what you would think it is, and that’s the size of the hard outer helmet casing, be that carbon fibre, or one of many other composite materials used. A helmet manufactured with only one shell size will have more padding to make it fit a smaller size head, where as a helmet with five shell sizes won’t as the shell size itself is mapped to the head size, not just the padding. 

But which is best? 

Current fashion is for a low profile fit, so the more shell sizes the better especially if you have a smaller head you would think. But the larger your head, the less relevant it becomes because you are going to need the largest shell size anyway; be that the only shell size or the biggest one if there is more than one. However, if you consider the extremes, an XXL helmet is typically for a 63cm circumference head, and XS is 54cm, the diameter difference is only going to be 2.8cm – so less than a centimetre and a half either side which is not a huge amount considering we are talking about the difference between the smallest and largest head sizes that helmets widely available cater for. It is the design and colour of a helmet that makes it look big or small, as much as the shell size itself so our advice is not to make the number of shell sizes a helmet comes in your main factor when deciding on a new helmet; it should only be one small consideration alongside the many other personal and functional preferences you may have. 

In our experience it is difficult to spot the difference between a helmet that comes in 2 shell sizes and one that comes in 5, and for at least 2 of these sizes there will be absolutely no difference, and for others we are talking only millimetres.