When you have determined your frame size, top tube and stem length from the table above transfer those measurements to the compact bike as follows:

     For example suppose you have decided you need a 54cm frame with a 54cm top tube and a 11cm stem. First measure 54cm from the center of the bottom bracket and mark that point on the seat post with a piece of tape. (Or in some other way that won't damage the bike.)

     Next add the top tube and stem length together in this example 54 + 11 = 65cm. Measure horizontally from the center of the seat post and 65cm should bring you exactly under the center of the handlebars as shown above. The handlebars should also be 9 to 12.5cm above this horizontal line; depending on your riding style. (Also please note because of the head angle the stem above the top tube is set back slightly so you may want to deduct 0.5cm. from your top tube plus stem measurement.)

     For optimum handling ideally the center of the front portion of the handlebars should be directly over the wheel center as shown in the drawing. If you are slightly ahead or behind this position it should not be a big problem but if you are some way off this may determine what size frame you finally decide on. Also you could choose a slightly longer or shorter stem to get the bars nearer the wheel center and adjust the seat back or forward; the maximum I would suggest adjusting the seat would be a centimeter either way and don't do this at the expense of a good riding position.

Transferring the above information to a compact bicycle.

(Above right) Traditional frame with level top tube. (Below) Compact frame.

Frames built in my shop were all measured center of the bottom bracket to an imaginary line just above the actual top of the seat lug as shown here. If a seat lug had an extra long point the measurement would still be to the same place.

     The above chart was prepared for frames built in my frameshop. You may not find the exact same seat tube/top tube combination from another manufacturer, so adjust the stem length accordingly.

     The chart was created over the years by experience and keeping records of customers measurements and frame sizes built for them. It was not devised by any mathematical formula.

     Important note: I measured all frames (Custom and Production.) from the center of the bottom bracket to the top of the seat lug. This was standard practice with English builders. Italian frames and most others measure center of B.B. to the center of top tube.

     (The chart shows C to C and C to T measurement.) There are two different ways of measuring a frame, both are widely used and both are acceptable. It becomes important when buying a frame to make sure the buyer and seller are in agreement. If one is talking center to top, and the other is thinking center to center, the buyer will probably end up with a frame the wrong size by about 2cm.

     Note: This chart is designed for an efficient racing position. If your interest is in a more leisurely style of riding this is still a good place to start. Rather than give you multiple choices simply use your own judgment and increase the frame size by up to 2cm. so there is less difference in the saddle to handlebar height and decrease the stem length by at least a centimeter.

     Go to Bicycle Related Downloads [Page 5.] for a copy of this chart in printable PDF format.

     Here is some information you may find helpful in choosing the correct size frame and setting up an efficient riding position.

     Human bodies do not come in standard sizes, but they do generally follow certain rules of nature. Tall people are not scaled up models of short people. The tall person has a body only slightly longer than the short person but their legs are much longer. People with long legs usually have long arms also; short legs; short arms.

     A rough estimation of frame size is to start by saying this equals two-thirds of the rider's inseam. (This is a starting assumption; other factors need to be taken into consideration.) This means that for the taller the rider, the amount of seat post showing out of the frame increases progressively. The resulting difference in the handlebar to seat height ratio accommodates the taller rider's longer arm length. The handlebar stem also increases in length for a larger frame. The top tube length on larger frames increases at a lesser rate, because the upper body length increases at a lesser rate.

     The exception to this two-thirds inseam rule is the rider with a long body and short legs. It is as if this body was designed as a very tall person, then the heel got turned further up the leg, making shorter legs and longer feet. The body and arms are as a taller person; so this rider needs a frame more suited to his overall height rather than his inseam measurement. The foot is a extension of the leg when riding a bicycle, because the toe points downward at the bottom of the pedal stroke. Therefore this rider needs to set the saddle higher to allow for their longer foot.

     The longer top tube and handlebar stem recommended for the larger frame will accommodate the rider's longer upper body and arms. The reverse of this is true for the rider with extra long legs and small feet. They would need a frame smaller than his inseam would suggest.

     I devised the adjoining chart to help you determine your best frame size. Look for your inseam measurement on the left. If your height is within an inch (2.5 cm.) and your shoe size within half a size of the one listed on the same line, then your frame size is a straight two-thirds of your inseam. If your height and shoe size is more or less than shown on that line, go for the frame size recommended for your height ignoring your inseam. For example, a rider with a 30 inseam, 5'8" tall and a 10 shoe (USA) should go for a frame around 54-55cm. A rider with a 36 inseam, 6'2" and an 11 shoe (USA) should have a 60cm frame.

     Another way to interpret the chart below; if your height and inseam do not fall on the same line. Look at the line where your height is; then look where your inseam is. This would be the two extremes of frame sizes; your best size is going to be somewhere in between. See which line your shoe size falls on and use that to decide which direction your best fit will be.

     Example: Height 5' 9 1/2" Inseam 30" Frame size between 56cm and 51cm. If shoe size is 10 1/2 (USA) choose a 54cm frame. If shoe size is 11 (USA) choose 55cm frame.