answer 1
Once you are into 26" wheel bicycles (road bikes typically have have 700c, 27" or 28" wheels), 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). In the UK and USA this is measured in inches, in Europe it is often in centimetres. 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, ask the shop and they should be able to tell you which way a particular bike is measured - or bring a tape measure!
The following rules of thumb should be applied when you try a bike for size:
Racing Bikes: Standing flat footed on the ground, you should have a minimum of 1" clearance between yourself and the top tube of the frame
Mountain Bikes: Standing 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) then 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 make sure that though you may be able to stand astride a bigger framed bike, that you can still comfortably reach the handlebars 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.
answered 1 year, 9 months ago
answer 2
I would recommend emailing sales@wiggle.co.uk with your height and inside leg measurement for bike size advice.
answered 2 years, 3 months ago