I’d like to take this opportunity to express my excitement at buying a new mountain bike! Whoo! Okay, now that that’s out of my system; if you’re in the process of looking at a new bike—especially online—it’s possible you’re having difficulty with the sizing. Good news, though; you’re not alone. In fact, one of the biggest issues people have, even when buying a bike in person, is that they don’t know what size to look for. Typically, sales associates or the experts at your local bike shop can help you out, but it helps to know your size. In this brief series, we’ll walk through the bike fitting process so you can feel confident about buying a bike.
The fit of your bike is the most important factor when choosing a new bike. Too small, and it can feel awkward and uncomfortable. Too large, and it could be even more difficult to ride, especially if you need to stop suddenly.
Bike sizes are typically based on a person's height and body frame, so you'll want to know your height, inseam, torso length, and arm length. The most important measurement you’ll need, though, is your inseam length (not your jeans size.) Also, be sure to remove your shoes prior to taking these measurements.
The frame size of a bike refers to the length of its seat tube, the measure of which is given in one of two ways: from the center of the bottom bracket to the top of the top tube (C-T), or from the center of the bottom bracket to the center of the top tube (C-C). While many bikes offer a size you're familiar with—S, M, L, or XL—others may offer a size listed in inches or centimeters as one number, such as 18.”
Road bikes tend to be more difficult to accurately fit than other styles and require a few more measurements to be precise. For instance, besides the seat tube length, you need just enough horizontal length on a road bike to let you comfortably stretch forward into your pedaling stance. You’ll want to multiply your inseam by .65 to get an accurate C-T or C-C measurement. Since the saddle height can be adjusted, don’t worry too much about it.
Taller riders, like me, may want to lean toward a slightly larger frame size when selecting a road bike. For example, a tall person with a 36-in inseam would require a 61-cm seat tube, but might actually prefer a 63-cm seat tube.
Choosing the right fit will make all the difference in comfort and performance when you’re riding. The wrong fit may lead to muscle pain, aches, and other issues in the long run, so be sure to take the time to find the right fit for you. Come back for part two, where we’ll take a look at mountain bike fitting.