Find and set your tyre pressure

Look for two markings on the tyre sidewall. The ETRTO size, for example 28-622: the first number is the tyre width in millimetres, the second the rim diameter. And the pressure range, for example "4.5–6.5 bar" or "max 95 psi".

Write down the width and the maximum pressure. If the rim also carries a maximum pressure, keep the lower of the two: that is the limit you never go above.

Weigh yourself in your riding kit, with helmet, shoes and backpack if you ride with one, then weigh yourself holding the bike: the difference is the weight of the bike. Add the two to get the total weight the tyres carry.

A road bike often weighs 8 to 10 kg, a mountain bike 12 to 15 kg, a loaded city bike or an e-bike 20 to 30 kg. Full panniers count too.

Start from the reference rear pressure for 85 kg in total: 7.0 bar for 23 mm, 6.3 bar for 25 mm, 5.5 bar for 28 mm, 4.5 bar for 32 mm, 4.0 bar for 35 mm, 3.3 bar for 40 mm, 2.8 bar for 45 mm, 2.4 bar for 50 mm, 2.1 bar for 54 mm, 1.9 bar for 58 mm and 1.7 bar for 64 mm.

Heavier means a little more pressure, lighter a little less: the pressure follows the total weight divided by 85, to the power 0.7. Take off 10 % for tubeless, then 0.2 bar at the front, which carries less weight. Example: a 75 kg rider on a 9 kg bike with 28 mm tyres and inner tubes gets about 5.5 bar at the rear and 5.3 bar at the front. Stay between 1.2 and 8.5 bar, and always below the sidewall maximum.

On a Presta valve, the thin one with a small nut at the tip, unscrew the lock nut a few turns and press it for a second to free the core. A Schrader valve, like a car's, is inflated directly.

Push the head of the Floor pump with gauge (or else Mini pump) on straight, lock the lever and pump to the pressure you worked out. Pull the head off in one quick move, check with the Pressure gauge (or else Floor pump with gauge) if the pump has no gauge, then screw the Presta lock nut back down.

Ride your usual route. If the bike bounces, your hands buzz or the tyre slips in corners, go down by 0.2 bar. If the tyre squirms in corners, you pinch the tube on a kerb or the rim hits a root, go up by 0.2 bar.

Tyres lose pressure every day, latex tubes and tubeless setups most of all. Check the pressure before every ride on a road bike, and at least once a week on a city bike.