Cycling jerseys can help keep you comfortable on the bike, prevent sunburn and give you a place to comfortably store the things you need to carry. But what's wrong with just riding in a cotton t-shirt anyway?
Wearing a cycling jersey isn't just about the right look. A cycling jersey can help keep you warmer in cold weather and cooler in warm weather and generally more comfortable. Because they're shaped to fit right when you're riding, jerseys help exclude drafts and keep the sun off.
Buyer's guides to cycling jerseys
Cut and shape
Cycling jerseys are cut long at the back and short at the front for on-bike comfort
Compared to a t-shirt, a cycling jersey usually has a longer back, shorter front, higher neck and sleeves shaped to fit when you're reaching for the handlebars.
There's a lot of variation in how closely a cycling jersey fits. Some are very close, especially if they're intended for racing. You don't want excess fabric flapping in the breeze if you're trying to go as fast as possible. This is usually called something like 'race cut'.
Other jerseys are looser and more flattering if you're not a racing snake. Look out for 'sport', 'city' or 'casual' designations.
One manufacturer's size L jersey will not be the same as another's, so try before you buy if at all possible. As a rule of thumb, Italian manufacturers tend to come up small, American-based manufacturers tend to be more generous.
Here comes the sun
Jersey fabrics vary in how effectively they block the sun. Some manufacturers provide an Sun Protection Factor (SPF) rating like that of sun cream to indicate how well they work. Look for high SPF ratings if you're riding in bright sunshine.
In early 2014 Chris Froome's girlfriend Michelle Cound tweeted this image of the sunburn Froome sustained training in a mesh jersey
Some very light fabrics provide little or no protection against the sun as Sky rider Chris Froome discovered while training in South Africa early in 2014. If you're wearing light mesh or open-weave jerseys, wear sunscreen underneath.
Long v short sleeves
A long sleeve jersey helps keep you warm in winter
Long sleeves are for winter, short sleeves for summer. Except it's not quite that simple. Very lightweight long-sleeve jerseys are good for pale-skinned riders in summer as they provide an extra layer of sun protection.
However, you'll usually find long-sleeved jerseys are made from thicker, warmer fabric than short-sleeved, to keep you warm in cold weather.
Many jerseys use different fabrics in different areas, such as more breathable mesh under the armpits
Most jerseys are made of some sort of synthetic fabric that's designed to quickly carry sweat away from your skin so it can evaporate from the outside of the jersey.
This is where cycling jerseys really beat your cotton t-shirt. Cotton soaks up moisture and retains it next to your skin. That water cools down in the breeze and makes you feel chilly unless the weather is very hot. Even then, it can still leave you too cold when you stop riding.
By moving sweat away from your skin, then, jersey fabrics help maintain a constant temperature.
One natural material that works well in jerseys is wool, especially fine Merino wool. Wool is still warm when it's wet, but surprisingly comfortable in warm weather too. Pong-causing bacteria grows far more slowly on wool than on synthetics, so a wool jersey can be worn multiple times between washes before it gets smelly. That makes wool popular with commuting cyclists who don't want to have to wash a bunch of jerseys every week.
Synthetic jersey fabrics deal with the pong problem by coating the fibres so that bacteria can't take hold. Repeated washing gradually removes this coating, so jerseys tend to get smellier more quickly as they get older.
The classic trio of rear pockets
Standard cycling jerseys have open-topped three pockets at the back for your wallet, keys, snacks and so on. You might think things could fall out of them, but in practice they're deep enough this isn't a problem, and there's usually a band of elasticated fabric across the top which also helps.
An extra pocket for valuables
Many manufacturers have introduced variants on the traditional trio of pockets. It's common to find a small zipped pocket for keys and change, or a pocket with a waterproof lining for your phone. The three may also be different widths, with a narrower pocket to stash a minipump.
Cycling jerseys almost universally have zips. Short zips look tidy, but you might want more ventilation if you're going to ride in warm weather.
A hidden zip
More commonly, the zip will extend to about the middle of the jersey front or right to the bottom so you can open it for ventilation when it's warm.
At the top of the zip, look out for a small flap of fabric that will cover the zip pull when it's done up. Amusingly called a 'zip garage' this stops the zip irritating your neck or getting caught in your beard.
Retro jerseys sometimes have buttons and collars, evoking the style of 1950s cycling
Our official grumpy Northerner, John has been riding bikes for over 30 years since discovering as an uncoordinated teen that a sport could be fun if it didn't require you to catch a ball or get in the way of a hulking prop forward.
Road touring was followed by mountain biking and a career racing in the mud that was as brief as it was unsuccessful.
Somewhere along the line came the discovery that he could string a few words together, followed by the even more remarkable discovery that people were mug enough to pay for this rather than expecting him to do an honest day's work. He's pretty certain he's worked for even more bike publications than Mat Brett.
The inevitable 30-something MAMIL transition saw him shift to skinny tyres and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.