Bike Sizing Advice

Perhaps one of the most commonly asked questions we receive is, "What size bike do I need?"

Unfortunately, there is no simple answer. But if you follow a few guidelines you should end up with a bike which is right for you.

If the bike is for a child, they generally fall into age categories based on the average size of a child of a specific age. There is no hard and fast rule that says that 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 on the bike, and they can manage all the controls ie turn the handlebars safely, reach the brake levers and operate them AND touch the floor with the ball of their foot, then there is nothing to prevent you from selecting a bike in a bigger age category. 

First Bikes; 12" wheels, suitable for average ages 3 to 5
Larger children may benefit from a 14" wheel cycle BUT these are generally made by toy manufacturers rather than genuine cycle manufacturers and tend not to last very long and are virtually impossible to get spare parts for.

Once a child has learnt to ride without stabilisers (generally about age 5) they will move up to a 16" wheel cycle. These generally do not come with stabilisers but they can be added if required.

Once you get into the realms of 20" wheel bikes and above, you may be offered multiple frame sizes. This has the benefit of being able to fit a younger child onto a bigger wheeled bike if they are confident riders. Although you will find that size options are generally not offered on a particular model, rather that different models have different frame sizes.

Once you are into 26" wheel bicycles, then size is only determined by Frame Size. The size of the frame is measured from the top of the frame at the point where the seat post is inserted, down to the centre of the axle carrying the pedal arms (bottom bracket). As we are in good old blighty, they are still measured in inches! (although a few european bikes are breaking this sizing trend). Unfortunately some manufacturers measure their models to the centre of the intersection of the top tube and the seat tube, which can throw some of the sizings out a little. If in doubt, please contact us and we'll be able to tell you which way a particular bike is measured.

The following rules of thumb should be applied when you try a bike for size;

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

Mountain Bikes; Stood flat footed on the ground, you should have a minimum of 3" clearance between yourself and the top tube of the frame.

A simple calculation can be used to estimate your required frame size if you are not able to sit astride a bike to measure;

Measure your inside leg measurement to the floor,
 subtract 3" (for mountain bikes, or 1" for road bikes)
subtract 10" (the average distance from the bottom bracket to the ground)

This will give you the maximum frame size that you will need.

But buying a bike of the correct size is not just about the height from the ground. As bikes get bigger height-wise, they also get longer. The distance from the saddle to the handle bars increases by on average 1" for every 2" increment in frame size. So you must also ensure that though you may be able to stand astride a bigger framed bike, that you can still comfortable reach the handle bars and manage all the controls. Remember that the saddles on all bikes are adjustable by between 4" and 10" so any bike can be tailored to fit you perfectly.

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