Running shorts are the one piece of kit you only notice when they are wrong. Nobody finishes a 10K thinking about how well the waistband behaved. They finish thinking about the thirteen minutes of thigh friction, or the phone that spent the last mile slapping against their hip like an aggrieved seagull.
Which is why most shorts guides are useless to us. They rank things by weight in grams and use the phrase “aerodynamic profile”, as though any of us are troubling the wind. So here is the ordinary runner’s version: what actually matters when you are buying shorts to move slowly through British weather in.
The five things that actually matter
1. The liner. This is the whole decision.
Everything else on a pair of shorts is preference. The liner decides whether you enjoy the run or spend it negotiating with your own legs.
There are three options. A brief liner uses the least fabric and runs coolest, but its leg openings sit exactly where your thighs meet, and over a long run those edges can quietly saw away at you. A boxer-brief liner covers more thigh and solves that, provided it is cut well; a badly cut one rides up inside two miles and then you are rearranging yourself at a pedestrian crossing in front of a bus queue. Unlined shorts are lightest and dry fastest, and require compression shorts underneath, which means you have bought two things instead of one.
Whichever you pick, look for a mesh liner rather than solid fabric. Solid liners hold sweat; mesh does not. On a warm day that is the difference between finishing damp and finishing swampy. The broader campaign against friction is covered in our guide to not chafing.
2. Fabric. Polyester, and then stop thinking about it.
Polyester is hydrophobic, which is a technical way of saying it does not want to hold water. Sweat moves through it and evaporates rather than sitting in the weave. Nylon is tougher and feels smoother against the skin, but absorbs more moisture and tends to hold heat, which on a humid British July afternoon is the opposite of what you want.
The practical answer is a polyester-elastane blend. The polyester deals with the sweat, the elastane provides the stretch, and the shorts move with your leg instead of arguing with it. Anything containing cotton is not running kit. It is a souvenir.
3. The waistband, which is where cheap shorts give themselves away
You want two things. A wide elasticated band, because a narrow one digs a red stripe across your middle and then folds over on itself somewhere around mile three. And an internal drawcord, because elastic relaxes as it warms up, and gravity is extremely interested in your shorts on a downhill.
If a pair has only the drawcord and no real elastic, you will spend the run tightening it. If it has only elastic and no cord, you will spend the run hitching it. Both, or walk away.
4. Pockets, and the great phone lie
Most shorts advertise a phone pocket. Most shorts mean a phone from 2016. Take your actual phone to the actual shorts and check, because a modern handset in a stretchy open pocket becomes a pendulum, and a pendulum on your hip for forty minutes is its own small punishment.
A zip matters more than the number of pockets. An open mesh pocket is fine for a gel and terrible for a key, and there is nothing quite like realising at the far end of a loop that your front door is now somewhere in a hedge.
5. Length, which everyone considers first and should consider last
Inseam is the most discussed and least important variable on this list. A 7-inch short is the sensible middle: long enough not to feel like a costume, short enough not to flap. Shorter runs cooler and exposes more thigh to the elements and to yourself. Longer covers more and can bunch behind the knee if it is cut badly.
Pick a length you will actually leave the house in. We went into far more detail than anyone asked for in our running shorts length guide.
What you are allowed to ignore
Weight in grams. The difference between a light pair and a heavy pair is roughly the weight of a satsuma, and if a satsuma is what stands between you and your goal time, the shorts were never the problem.
Reflective detailing sold as a safety feature. A three-centimetre silver flash on the hem is decoration. If you run in the dark through a British winter, that job belongs to a proper reflective vest or a head torch, and it is worth doing properly.
Anti-odour treatments. Most are surface finishes that fade with washing, and by then the smell has taken up residence in the fibres regardless. That is a laundry problem, and we wrote about why running kit still smells after washing instead.
Three tests before you commit
The squat test
Put them on and squat all the way down in front of a mirror. You are checking two things: whether the fabric goes see-through under stretch, and whether the waistband slides. Better to find out in a bedroom than on a start line.
The stair test
Go up and down a flight quickly. If the liner rides up in twelve steps, it will ride up in twelve thousand. This takes fifteen seconds and saves entire race days.
The twenty-minute rule
Nothing chafes in the first ten minutes. Never judge shorts on a lap of the park. Give a new pair one honest, unhurried run of at least twenty minutes before deciding, and never debut anything on race day.
What we ended up making
We built the 7" Suffer Shorts against exactly this list, because we had all owned the shorts that failed it. 92% recycled polyester with 8% elastane for four-way stretch. An internal mesh liner. A zip pocket that takes a real phone. Elasticated waistband with an internal drawcord, so they stay up even when the hill turns downward and your form abandons you.
Shorts are only one front in the friction war, mind. If your feet are the problem rather than your thighs, the Blister Socks are the cheaper fix, and the Agony Tee handles the half of you that shorts cannot reach. The rest of it lives in The Kit.
Common questions
Do I need to wear pants under lined running shorts?
No. The liner is the underwear. Adding cotton pants underneath puts a wet, seam-heavy layer exactly where you least want one, which is how most chafing stories begin.
How much should I spend on running shorts in the UK?
The useful features on this page turn up somewhere in the middle of the market. Below that you tend to lose the zip pocket and the decent liner first. Above it you are mostly paying for a logo and a claimed gram saving.
Can I wear running shorts in winter?
Plenty of people do. Legs generate a lot of heat once you are moving, and cold knees are usually just a first-mile problem. If it genuinely bothers you, add a layer on top rather than switching to tights.
Why do my shorts ride up between my thighs?
Usually a liner cut too narrow for your build, or a fabric with too little stretch to recover. A boxer-brief liner or a slightly longer inseam normally fixes it. Persistent riding up is a fit problem, not a technique problem.
How many pairs of running shorts do I actually need?
Two, if you run three times a week and do laundry like a normal person. Three if you would rather never think about it. Beyond that you are collecting.
Related reading
If you are assembling a wardrobe rather than replacing one pair, start with the minimal running kit list, which is shorter than you expect. For the question of what goes on top of the shorts in each kind of British weather, there is our temperature guide. And if you have already got the friction problem rather than the buying problem, go straight to how to stop chafing.
Buy the boring pair. Suffer every mile. Still no medals.