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, cycling jerseys help exclude drafts and keep the sun off.
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 cycling 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 cycling jerseys 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.
Cycling jerseys 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 a light mesh or open-weave cycling jersey, wear sunscreen underneath.
A long sleeve cycling 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 cycling 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 cycling jerseys are made from thicker, warmer fabric than short-sleeved, to keep you warm in cold weather.
Many cycling jerseys use different fabrics in different areas, such as more breathable mesh under the armpits
Most cycling 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 cycling 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 cycling jerseys every week.
Synthetic cycling jerseys fabrics deal with the pong problem by coating the fibres so that bacteria can't take hold. Repeated washing gradually removes this coating, so synthetic cycling jerseys tend to get smellier more quickly as they get older. Eventually their ability to resist getting whiffy will be so poor that your loved ones won't want you in the house straight after a ride. That's a clue you need to buy a new cycling jersey.
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 cycling jerseys manufacturer 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 cycling jerseys sometimes have buttons and collars, evoking the style of 1950s cycling
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Acknowledged by the Telegraph as a leading cycling journalist, John Stevenson has been writing about bikes and cycling for over 30 years since discovering that people were mug enough to pay him for it rather than expecting him to do an honest day's work.
He was heavily involved in the mountain bike boom of the late 1980s as a racer, team manager and race promoter, and that led to writing for Mountain Biking UK magazine shortly after its inception. He got the gig by phoning up the editor and telling him the magazine was rubbish and he could do better. Rather than telling him to get lost, MBUK editor Tym Manley called John’s bluff and the rest is history.
Since then he has worked on MTB Pro magazine and was editor of Maximum Mountain Bike and Australian Mountain Bike magazines, before switching to the web in 2000 to work for CyclingNews.com. Along with road.cc editor Tony Farelly, John was on the launch team for BikeRadar.com and subsequently became editor in chief of Future Publishing’s group of cycling magazines and websites, including Cycling Plus, MBUK, What Mountain Bike and Procycling.
John has also written for Cyclist magazine, edited the BikeMagic website and was founding editor of TotalWomensCycling.com before handing over to someone far more representative of the site's main audience.
He joined road.cc in 2013 and these days he lives in Cambridge where the lack of hills is more than made up for by the headwinds.