How to measure a bike frame

For a simple machine, a bike is actually quite complex. How it rides and how easy it is to operate will be affected by considerations such as its groupset and gearing, wheels and tyres. That’s before you consider frame materials and construction and a bike’s aerodynamics. 

But the most significant impact on a bike’s handling and ride characteristics is its frame’s geometry. A geometry chart will feature in the specifications for almost every bike and can be found online on bike makers’ and retailers’ product pages. 

Usually accompanied by an annotated diagram of the bike’s frame, the geometry chart is a series of linear and angular measurements which define a bike’s geometry and will differ by frame size. But what do all the figures mean and how do they affect the bike’s fit and ride?