Both the driver of the motorcycle and the passenger alike should be wearing motorcycle apparel that protects them in case of an accident. Bikers wear leather clothing that is durable so they will be well protected if a crash occurs. Just because passengers may be in a bit better position than the driver doesn’t mean they should be careless with what they wear.
The passenger does not need to worry as much about debris or anything flying in their eyes, since their face will most likely be hidden by the driver anyways. They can still wear goggles or a full face helmet if they wish, though. Otherwise, a regular helmet would do.
Since the wind will be mainly blowing on the driver and passengers are behind them, they don’t have to worry quite as much as the drivers have to about that. However, it will still be cold, so they should be sure to have a motorcycle jacket on. It will also help protect arms in case of a crash.
Gloves are another thing that passengers need to worry less about than the driver. A driver’s main use for the gloves is to get a better grip on the handlebars, as well as to keep their hands from hurting if they’re riding too long. Passengers aren’t the ones driving, so they don’t need to think about that. However, gloves are also good for keeping hands warm if it is cold, even protecting hands if they happen to fall. Therefore, passengers may still want to take a pair with them, just in case.
Everything else that a driver has to worry about, the passenger really should, too. Wear boots to protect the feet. Wear motorcycle pants to protect the legs. Anything that they would wear as a driver, they should wear as a passenger as well. They are out in the open just like the driver, so they still need to be sure that they are as safe as possible. Perhaps they are better off while riding, but if they happen to crash, they would be hurt just as badly. Chuck Hawks describes other tips for motorcycle passengers that they should be sure to follow.