A pump should be your first purchase once you have found your bike. Having a flat or heavily deflated tyre is like riding through treacle and an experience to avoid. We advise always taking a mini pump along on your ride and keeping a larger floor pump for home use (usually fitted with a pressure guage). Just like car tyres, bike tyres will deflate even when not punctured and keeping them to the correct pressure eases pedalling and helps with traction (the recommended psi is usually printed on the side of the tyre). Should you get a dreaded puncture on your ride, a mini-pump and tube will ensure you are able to continue your ride.
There are two common Valve types and a couple of older styled, less popular ones:
Most pumps are compatible with the two most popular valve types - Schrader and Presta (or will have an adapter supplied).
Schrader (car type valve): Traditionally this valve type is mainly found on mountain and hybrid bikes which are usually run at a lower air pressure.
Presta: Commonly fitted to road/racing bikes and more recently some mountain bikes and urban/city bikes. Suitable for tyres run at a higher air pressure usually a narrower tyre.