The bicycle market has grown massively in recent years, which can make it confusing but you can be sure there'll be a bike perfectly suited to you out there somewhere.
You can find many of our expert bike reviews in our gear section.
Mountain bikes have been very popular in the UK since the 1980s, and their upright riding position, flat handlebars, and fat tyres make them attractive to new cyclists.
They usually have 20-30 gears, with a front and rear derailluer mechanisms.
However, you don't really need an off-road bike in London, and the extra weight and friction from fat knobbly tyres (ideal in thick mud) will slow you down.
Again, suspension isn't really necessary on normal London roads, though if you ride year-round on towpaths, a mountain bike could be for you.
Known for their drop handlebars and skinny tyres, road or racing bikes have lightweight frames and a more hunched-over riding position.
Again they usually have 20-30 gears via front and rear deraileurs.
They can make excellent speedy city bikes, though very skinny tyres can be vulnerable to potholes.
Touring bikes usually have slightly fatter tyres and a wider range of gears, and can be fitted with a rack and mudguards.
Track, singlespeed and fixed-gear bikes have a racing-style frame but just one gear.
They're practical in London because of the lack of hills (in the centre at least), and because they can be lighter, cheaper and easier to maintain than a geared bike.
Hybrids often combine the more comfortable riding position and flat bars of a mountain bike, with the lightness of a racer. They usually dispense with suspension too.
Flat bars allow rapid and powerful braking, while the upright position is helps you see well, and thinner tyres make for a quicker ride.
Some modern bikes are based on older designs, which include a steel frame for longevity and a small number of hub gears (rather than derailleurs) – say between one and five – for reliability.
People are attracted to these Dutch-style roadsters by their reliability and practicality, though they can be heavy.
Folding bikes do just that, and many can be taken on public transport or stored at home or elsewhere, if you're short of space or don't trust locking up in public.
Most use smaller wheels than non-folding bikes, which affects the riding characteristics and arguably makes them less suitable for longer rides.
There are many variations of the recumbent design, but most are ridden in prone position, so your legs are horizontal in front of you.
These bikes are good for those who experience problems with the forward-leaning posture and pressure on knees and wrists.
On some types you will be very close to the ground, and visibility can be reduced.
Tricycles are three-wheeled bikes, and come in all shapes and sizes: racing, recumbents, tandems, load carriers or designed for disabilities.
Trikes are very stable, and may be good for people who have trouble balancing a two-wheeled bike, and they have extra strength for carrying big loads, including children.
Their size is their biggest drawback.
Electrically assisted bikes are more expensive than conventional bikes and also heavier, but they can be useful for people who are unable to ride a conventional bike or require power assistance on some journeys.
Contrary to expectations, electric bikes are generally slower than conventional bikes (they're limited to 15mph when powered) and, because of their weight, less manouverable.
They also have a limited range, and if the battery runs out they are harder to pedal than an ordinary bike.
Any of the above types can be custom-made, making sure it fits you precisely, and that you control the exact specifications.
Expect the cost of a custom bike to be considerably more than an off-the-peg model.