Motorcycles have many safety features, but you can’t forget to protect your head. While you may purchase a used motorcycle or used gear, you shouldn’t buy a used motorcycle helmet. Here are a few reasons why.

Motorcycle helmets break, but you can’t see inside

Motorcycle helmets are good for one crash only. In an accident, the outer shell cracks and the inner shell compresses, cushioning your head. That inner shell can only compress one time though. You don’t want a helmet that’s been in a crash or shows any external damage.

You don’t want any internal damage either, but you’d have to remove the outer shell to see inside the helmet. Even helmets that haven’t been in a crash could be damaged if they’ve been dropped. If a helmet falls from four feet or higher (whether your head is in it or not), it should be replaced. The best way to get an undamaged helmet is to buy a new one.

They expire

Motorcycle helmets all expire after a few years, even if they haven’t been used. Exactly how long it takes depends on the materials. Polycarbonate helmets expire after about four years, and composite helmets expire after six or seven years on average.

You want a helmet made of fresh materials at their peak ability to absorb the shock of a crash. When you buy a helmet, look under the inner lining to find a sticker showing the production date, and make sure it’s a recent date. If there’s no sticker, you’ll have no idea of the helmet’s age.

Motorcyce helmets wear out

While helmets expire after four to seven years, how long it takes a particular helmet to wear out depends on its quality, how much it’s worn, and how well it’s cared for. A helmet exposed to rain, UV rays, or extreme temperatures will age faster. With enough time, the inner shell will harden and get brittle. If it’s too hard to compress, it won’t protect your head.

Helmet technology evolves

Motorcycle helmets have been around since the early 1900s, and their design technology continues to evolve. Today’s helmets include materials like carbon fiber and Kevlar®. The newest helmets include Bluetooth connectivity and will soon have augmented reality displays. Vintage helmets will already be expired and won’t meet today’s safety standards.

Motorcycle helmets are dirty

While not a safety risk, helmets pick up lots of sweat and hair products. It isn’t common to get lice from a helmet, but it is possible. If hygiene is a concern, the cleanest motorcycle helmet is a brand new one.

Helmets fit their owner’s head

Like sneakers, motorcycle helmets have an inner lining that shapes to the wearer’s head over time. A used helmet won’t fit as well for a new owner and may feel uncomfortable. Any space inside the helmet means it could wiggle, reducing its effectiveness in a crash.

Guest helmets may have the same problems

A used guest helmet may not have been used much. It might still look like it’s in great condition. However, it could have all of the aforementioned problems. Plus, you can’t actually confirm that the guest helmet really only had occasional use and isn’t old or damaged.

While it’s great to save money, don’t do it by buying a used motorcycle helmet. The safety of your head isn’t worth it.