Getting Started

Bikes are powered by a two-stroke engine – your legs. In order to get the best performance from that engine, your bike needs to be sized correctly. Even if efficiency and speed aren’t your priority, sizing plays an equal part in making your bike comfortable. So the better the fit, the more comfortable and efficient your bike will be.

What to measure?

In order to size a bike correctly you should consider your height and inside leg measurement along with your riding style and the style of the bike itself.

Measuring your height is best done by standing upright against a wall with your legs together (shoes off) and shoulders back. Place a pencil on top of your head, holding it parallel to the floor and mark the wall. You can now measure your height easily against the wall.

Your inside leg measurement is taken from the floor (again, no shoes) to your crotch. Stand with your legs roughly shoulder width apart against a wall, then take your inside leg measurement. It is probably easier to get someone to do this for you.

It's about clearance not contact

The distance between you, specifically your crotch and your bike’s top tube (a.k.a. crossbar) is known as clearance. Clearance is indicated by standing over the bike, forward of the saddle and measuring the distance from your crotch to the top tube.

It is important to be able to stand safely over the bike when stopped. Therefore, a clearance of at least two inches should exist on all the bikes you ride. It can be thought of as a safety net to prevent injuring yourself if you need to jump forward of the saddle suddenly.

How are bikes sized?

All adults’ bikes are measured by their frame size. This is typically the length of the seat tube – the near-vertical tube that the saddle and seat post slide into. Manufacturers will measure these slightly differently. However, the rule of thumb is to measure from the centre of the bolt which fastens the crank arms, all the way up the frame, to the top of the seat tube. Some brands (especially American) stop short of the top, only measuring to the point where the top tube meets the seat tube.

Personal choice does play a factor

Bikes are designed to have their saddles raised. That is to have some of the seat post showing (e.g. as the above illustration). The amount riders wish to raise or lower their saddles is a matter of personal choice. Some riders like the saddle to be higher than the handle bars which means their hands are low when riding, giving them an aerodynamic position. Others may prefer a more comfortable ride with their hands level or even higher than the saddle height, giving a more upright position (a.k.a. sit up and beg).

This is where style will play a factor: a grandmother riding a hybrid to the shop 1 kilometre away is likely to want comfort not aerodynamics; whereas the off-road speed demon will be looking to size for efficiency and not care about straining his lower back.

For an example of choice, let’s highlight two riders in the Wheelies office. One is 6’1” and rides a 17” Kona hardtail with an extra long seat post raised to its maximum. This is a very small frame for his height which gives him huge clearance and plenty of manoeuvrability as he can easily throw the bike around. Another chap is 5’8” and rides an 18” Specialized hardtail. Chap 2 also has lots of seat post showing, perhaps 7”, and also feels he can manoeuvre the bike easily. Both are correct because both are comfortable with their frames and their style of riding.

Your measurements, confidence, riding style, previous bikes, model choice etcetera will all play a part in sizing correctly. For a general guide follow our chart below. Please remember that these are only guidelines and personal opinions may differ. We are always happy to discuss frame sizes with you – please call customer services on 01792 583000.