Racing bike frame size is measured the same way as other bikes. All chart guides for these account for the seat tube length and the length of the inseam.
As stated, the frames are dependent on the size of the tube. The tube is what keeps the seat in place. The frames in most road bikes are measured in cm. However, this is not always the case with racing bikes. Adding to the confusion is that there are different standards used. However, the measuring process is the same.
To get racing bike frame size, the measurement will begin at the bottom from the middle of the low bracket. However, it is also possible to obtain the figures from the seat tube’s top. You can also get the same numbers via the upper tube to the area where the top tube connects with the seat.
The Stand over Height
This is another method used to determine if a bike is the right size for you. Simply put, you must be able to straddle it with your feet set on the ground firmly. There has to be some clearance between your crotch and the tube. The space between the upper part of the top tube and the ground is the actual stand over height. The inseam has to be one inch. In centimeters this is 2 1/2 cm more than the stand over height.
Finding the right racer bike is just about matching the bike and your physical stature. Bigger frames are needed by tall racers. The reverse is true for petite individuals. Charts and sizing guides are freely available on the Internet. Apart from browsing the Internet, you will find this information in bike shops. The people there can give you information on getting the right bike.
Note on Inseam Measurements
This should be measured while standing barefoot. Measure from the floor up to your crotch. One method is to stand against a wall. Get a book and set it in between your legs. Make a line on the wall using the tome’s top binding as reference. Get the distance from the line to the floor. The result is the inseam.
Racing bike frame size charts are easy to find on the Internet. They also provide references for height. But these are just guides. It is best to still go into a shop and get a feel for the bike.