THE ROAD BIKE FRAME

Selecting a frame size is the beginning of good positioning. The perfect bike size is simply one that will allow you to train and race. The saddle can be raised and lowered and the seat post can be replaced with a longer or shorter post to accommodate nearly anyone.

Saddle height is not the limiting factor in selecting a frame size. The placement of the handlebars will be much more limited than the saddle height. If too small a frame is selected, the rider must bend over quite low to reach the bars. A frame that is too large will put the rider up too high. This tends to make less use of back and leg muscles and place the body in a less aerodynamic position.

Frame sizes are measured along the seat tube. The method of measurement is center to center, center to top when selecting a frame size. Different manufacturers may use slightly different measurement techniques.

There are several commercially available positioning systems that take a series of body measurements and plug the numbers into tables and charts to come up with frame-size recommendations. You should use any system with caution and never purchase a bicycle solely on that basis alone. Ride a variety of sizes while being observed by a coach. Purchasing a frame size without having ridden it is a big risk.

One of the simplest methods of determining a bike size is one of the oldest. Wear a low-profile shoe, preferably the shoe you will be wearing while riding. Stand over the bike directly behind the stem with your feet close together. Pick up the front wheel until the top tube is snug against the crotch, then measure the gap between the floor and the tire.

For competitive purposes this gap can be between 6 and 20 centimeters. The smaller gap of 6cm means the frame is relatively large. The gap of 20cm means the frame is smaller. If you have long arms or you feel you need a very large differential between saddle and bars, a frame size with a 15-20cm gap is recommended. However if you have a stiff back, a frame with a smaller gap might be preferred

If you choose a sloped frame bicycle, these recommendations will not apply. The determining factor in selecting a sloping tube bike is the top tube length rather than the seat tube length. USA Cycling recommends using a “fit specialist”.

Younger cyclists who are expected to grow can select a frame with a lesser gap so that the bike will not be outgrown too quickly. A shorter stem may be installed and then switched to a longer stem as the rider grows. The height of the parents and siblings should be considered when choosing a frame size for a growing rider.

These procedures are not intended to get the rider the ideal bike size the first time. This is simply a place to begin test riding. You should test-ride at least three different frame sizes if possible. The most important thing about any bike is finding the correct size and fit for the rider.