How to Choose the Right Size Frame

and how to set it up to fit your body correctly

It's important to choose a bike that fits correctly not only for safety considerations but also for maximum comfort and control. This page should help you with both choosing the correct frame size (or wheel size for childern) and then how to tailor its set up for yourself.

Childrens Bike Sizes

Age	Wheel Size
2½ - 4 Years	12" Wheels
4 - 5 Years	14" Wheels
5 - 7 Years	16" Wheels
7 - 9 Years	20" Wheels
9 - 11 Years	24" Wheels
11+ Years	26" Wheels
If your child is larg or small for their age you might need to adjust your choice of wheel size accordingly.

Be aware when buying 12" and 14" inch wheel bikes as many of them are simply just toys, not bikes. By this I mean that istead of genuine steel ball bearings in the wheels they have plastic bushes. Although these can prove satisfactory, many manufacturers don't supply the spare parts for the bushes which are usually necessary as they wear down relatively quickly.

Adult Bike Size

Once you're large enough to fit on a 26" wheeled (or 27"/28" for some road bikes) the size of a bike is determined by the frame height which is usually given in inches (centimetres in Europe) and is measured from the bottom bracket (where the pedals are attached to the frame) to the top of the seat tube. Although some manufacturers measure from the bottom braket to to the centre of where the crossbar meets the seat tube. Is this just to trip you up a little with choosing the right fram size? Who knows - but if you're buying from a shop they should be able tell you which is which.

Here are the two main rules for choosing your frame size.

Mountain Bikes: You should have at least 3" between the crossbar and yourself
Racing Bikes: You should have at least 1" between the crossbar and yourself

An alternative to this, if you don't have a bike available to try out, is to measure your inside leg and then subtract 1" for a road bike or 3" for a mountain bike. Once you've found your frame size bear in mind that as the frame size increases the length between the saddle and the crossbar will also inrease. So you'll need to make sure you can still stand astride the bike and still comfortably reach the handlebars. You can reduce or inrease the distance by adjusting the saddle (which can usually be moved forward/backward by at least 4") or buying a different head stem. You'll also need to bear in mind that a 18" road bike frame will be very different to 18" trials or mountain bike frames.

How to Set Up Your Bike

The problem with setting upa bike is that you can find a lot of "rules" on how you should do this. This page doesn't deal with anything that rigid and is just a few guidelines based on what I've read and what works for myself, my family and my friends.

Saddle Set-Up

The simplest way to set your saddle height is to arrange your crank so it is aligned vertically with the stem. Then whilst sitting on the saddle your heel should just touch the lower of the two pedals (whichever side that is). It is important that you don't tilt your hips to either side of the saddle when setting your saddle height. After this you can set the fore-aft position of the saddle. I go with what feels most comfortable, usually quite far forward so I work the bike easier over rough terrain but for power and economy this is the general rule: Arrange your crank/pedals so that they are horizontal, loosen the saddle and slide it backwads then slide it forward until your front knee (well the little bump just below the knee cap) is directly bove, or just behind the center of the pedal.

Once you've got your saddle height and fore-aft amount set you'll want to check the tilt of your saddle, make sure it isn't tilting backward at all - this usually causes a strain on your lower back. Most people recommend completely flat (use a spirit level to check) but I like mine tilted slightly forwards.

Handlebar Position

In general having your handle bars further forward will give you more power and be able to attain higher speeds but the closer they are to you the more comfortable you'll be and the better you'll be able to control the bike over rough terrain (if doing any type of mountain biking). Handlebar with is a personal choice but generally for road biking the bars are narrower, a little wider for cross-country cycling and wider again for downhilling or jumps.