What size bike do you need?

Fitting a bike is a personal thing, and lots of people will give you different advice. A key thing to remember is that the exact fit is achieved by adjusting saddle height and position, stem height and angle, etc. Below we have provided some best-practice guidelines for picking the size of frame. A few other useful tips:

  • What is the size and geometry of the bike you ride today? Are you happy with it?
  • Talk to the seller of a bike you are interested in - how tall are they? How was the bike fit for them?
  • Check the manufacturer's website for details of frame geometry and fit.

Road bikes

The simple version...

For a quick, simple and visual guide, this graphic from Machine Bike is about as good as it gets:

The more detailed version...

The following excellent chart from ebicycles shows the frame size (in cm) to look for based on your height and inseam. They also have an online calculator that gives you the same results.

The really quite complicated version...

If you want a more sophisticated way of calculating size, head over to Competitive Cyclist and their excellent Fit Calculator. You'll need to take a total of 7 measurements, and its best to have a friend to help you with the measurements.

 

Mountain Bikes

Road bikes are measured in cm - presumably because the sport originates in Europe. Mountain bikes are measured in inches - presumably because of US origins. Often Mountain bikes just have a XS-S-M-L-XL type sizing. Because of all the different suspension and ride types, mountain bike sizing is somewhat more vague. Just like road bikes, the fit is adjusted with stem, seat post, etc.

The simple version...

This article by Singletracks is a good overview, not just of frame size but all the elements of bike fitting.

The more detailed version...

Again, the folk at ebicycle have produced a good chart (below) and online wizard to help find the right frame size:

The really quite complicated version...

If you want the sophisticated version, then head on over to Competitive Cyclist with a tape measure and a friend who doesn't mind reaching into your nooks and crevices.

In summary - if you think the bike is going to be the wrong size - its probably is. Otherwise...