What size Bike Do I Need?

Question: How do I determine the size road-racing frame to buy?

Hi Hannes, I hear S.A. is the place to go cycling these days, it looks really nice, so I don�t blame you for getting a new road bike, a lot of the pro�s have been going training there in the winter, very nice.

To work out the size of bike you need is a little bit difficult and not so straight forward, there are a few different ways of doing this, of course you could go for a compact design of frame, these come in small, medium and large, so you need to find the correct size frame, remembering to look at the top tube length, which is also very important.

With all new bikes the manufacture will give advice as to which size of frame for your inside leg length, the basic rule is 10 inches (26 cm, approx) less than your inside leg length is the size of frame you need, i.e. 29 inch inside leg then you need a 19 inch frame. This holds true in smaller frames up to a 33-inch inside leg, for longer legs then you should subtract a little more up to 12 inches from a 38-inch inside leg length. This is only a rough guide and with experience you get to know your exact frame size.

The measurement of the frame is from the middle of the bottom bracket to the top of the seat tube in most countries, the Italians tend to measure from the middle of the bottom bracket to the middle if the top tube, so this is something you have to be careful over.

There are other methods of finding your exact bike size, many bike shops have measuring equipment that also works out your position on the bike with crank length, stem length and saddle position, this is a very good way of calculating your position for first time buyers.

Good luck with your new bike and we hope you enjoy your riding. Remember its always good to listen to your bike shop, they should be very helpful.

Read more about frames in our popular article Choosing your Bicycle frame