Types of bike pumps
When considering which pump to buy, think about whether you need higher pressure or more volume; pumps that put out a lot of air with each stroke might not be able to reach pressures as high as those that only put out a little air each time. Because of this, many brands offer pumps specific to road biking (where higher pressures are needed) or mountain biking (where more volume is useful).
Track pump
Also known as floor pumps, track pumps are the fastest and most efficient way of pumping your tyres up. They usually have a long flexible hose, pressure gauge and a large chamber for generous air transfer, meaning you get more air in your tyre for fewer pumps. Every cyclist should have one of these in their garage.
Hand pump
Hand pumps are portable pumps designed for emergencies and occasional use. Because of their small size, they can take a while to pump up your tyre which is why it's a good idea to keep a track pump at home.
When you're looking for a hand pump, you'll need to take into account the pressure your tyres need. If you have a road bike, look for a pump that's suited to high-pressure inflation (measured as psi), and if you have a mountain bike, look for a pump that's suited to high-volume inflation.
CO2 inflators
A portable alternative to hand pumps, a CO2 inflator can inflate a tyre in seconds using compressed carbon dioxide. A single 16g canister will inflate a standard 700 x 23c road tyre to about 100psi. However, each canister is single use so you're out of luck if you need more than you've brought along with you.
Another thing to remember is that canisters can get really cold, so make sure to use one with a cover or wear gloves when operating it.