cycle measurements

There are a number of ways to do this, not all are suitable for all individuals. Also, as the number of different frame designs multiplies, this becomes a harder and harder question to answer. Here are some methods that are worth trying to give you a starting point, but the best answer is still to go to a reputable cycle dealer and test-ride a few bikes of various sizes until you find one that feels right?

Sports Bikes: Try your height divided by three as the frame size. Try your inside leg less either 10 inches or 25 centimetres, also as the frame size. Sit on a bike with the saddle set at a height that allows you to set your heel on the pedal with your leg 'locked' at the bottom of the pedal stroke, but with your hips level (this is also one way to set saddle height). Assuming you are a full grown adult, a standard road seatpost (220mm long overall) should be at or near it's maximum extension, but bear in mind this works only for conventional frames with a level top tube. Other designs of frame need careful consideration to achieve correct reach and diparity between saddle and handlebar height, Use one of the sizing analysis systems on the market, like Bio-Racer or BikeFit. Listen to a reputable retailer and take his advice!

Touring and Commuting Bikes, Hybrids: Inside leg measurement less 9 inches or 22cm. Setting a saddle height by the method outlined above, about 1 inch or 25mm less of the seatpost should be showing out of the frame than suggested for sports use. Bear in mind that many hybrids have a top tube that slopes back from the head tube, so that you will have to compensate for this. Generally,with 'drop' bars, a smaller difference between saddle and handlebar height than for racing orsports use is to be recommended.

Mountain Bikes: There is an increasing tendency, especially amongst the more specialist manufacturers to simply size their bikes small, medium and large, and then to compensate for differences in reach with different length handlebar stems. In general, one should ride an MTB about 4 or 5 inches smaller (10 or 12cm) than a sports bike the right size. Beware though of some manufacturers tendencies towards long top tube measurements, or idiosyncratic measurement systems.

The bottom line is still to visit a competent cycle dealer and trust his advice. If you don't know, or are unsure of who you can trust, go on personal recommendation. As a last resort (you won't make yourself popular with two out of the three dealers concerned), get sized up by three retailers and take an average!