It is very important when buying a bike, any bike, whether it be your first or 21st, to get the correct size of frame.

Sizing for children

If the bike is for a child, you will need a bike that will last as long as possible by providing plenty of 'growing room', but at the same time, not being dangerous because the bike is too big.

Bikes for children are generally grouped into age categories based on the average size of a child at a specific age. However this is not etched in granite and there is nothing that says you must buy a bike of a particular size for a child of a specific age. If the child is comfortable and not too stretched; they can turn the handlebars safely, reach and operate the brake levers and touch the floor with their tip-toes, then there is nothing to prevent you from selecting a bike in a bigger (or smaller) age category.

The general classifications are as follows:

First bikes or pavement bikes are 12" wheel for average ages 3 to 5. However larger children may benefit from a 14" wheel cycle. Once a child has learnt to ride without stabilisers they can move up to a 16" wheel cycle.

20" wheel bikes and above are usually offered in various frame sizes. This offers the benefit of being able to put a child onto a bigger wheeled bike if they are confident riders.

Once riding a 26" wheel bike, then size determined by the frame size. The size of frame is generally measured from the centre of the chainset to the point where the seat post is inserted into the frame. Though some manufacturers measure them differently so check before you buy.

The following rules of thumb should be applied when you are able to try a bike for size:-

Mountain bikes

Whilst standing flat footed on the ground, you should have a minimum of 3" clearance between you and the top tube.

Road bikes

Stood flat footed on the ground, you should have a minimum of 1" clearance between you and the top tube.

If you cannot stand astride the bike, a simple calculation can be used to estimate your required frame size.

Measure your inside leg measurement to the floor. Subtract 3" for mountain bikes, or 1" for road bikes. Then subtract 9", the average distance from the bottom bracket to the ground. This will give you the maximum frame size you will need.

The main thing to remember is that a bike which is too big, can be extremely dangerous.