Choosing the right size is the most important factor when picking out a bike so it’s important to know everything you’ll need to consider. From frame size to saddle height, fine-tuning your ride can make the difference between a bike that sits unused and one you’ll want to ride every day.
First, let’s cover the basics.
How long is the standard bicycle? The average bike is 68 inches long from wheel to wheel. Bike frames typically fall within a range of 48-60cm with corresponding sizes between extra small and extra-large, depending on the brand.
Here is what you can generally expect for road bike sizes:
|Frame Size (cm)||Bike Size||Rider Height in Feet (min)||Rider Height (max)|
Specialized has recently come out with a new way of measuring their mountain bikes, called S-Sizing, which isn’t included above. (Source)
Keep in mind that the measurements above are only for the frame. Tires can come in different diameters, which adds to the overall size of the bike, but doesn’t affect the bike’s fit.
It’s also important to remember that this is just a general guideline and the exact sizing will vary from bike to bike, even within the same brand. Always check with the brand’s sizing guide for a certain bike before you make any purchases, especially if you’re ordering online.
If you’re on the cusp of sizes, you’ll have to make a choice. For example, someone who is 5’7” could fit on either a small or a medium bike, depending on the brand. Choosing the smaller size would typically result in a more nimble, agile ride, while the larger size would feel more stable.
Again, this will range between brands and bikes, so look closely at the sizing guides and suggestions. If you can, try both sizes at your local bike shop. You can talk with the sales associates and bike fitters to see which size is best for you and nothing beats taking it for a spin.
Frame size is just one component of overall bike fit. You’ll also want to make sure that your arms, torso, and legs are in the proper positions to avoid any discomfort or even potential injury. Those can usually be adjusted to fit your size.
- How Do You Size Yourself for A Bike?
- How Do I Know the Bike Is the Right Fit?
- Is It Worth It to Get a Professional Bike Fitting?
- Is There a Difference Bike Criteria Based on Gender?
How Do You Size Yourself for A Bike?
Most bikes will list their sizing guides by rider height. If you just use that, you’ll have a decent chance of getting a bike that fits you well enough. However, if you want to get a bit more advanced, you can do your own bike sizing at home with a few simple tools and Competitive Cyclist’s handy bike fit calculator. (Source: Calculator)
There you’ll find exact details on how to make the measurements, but here’s a general overview.
What you’ll need:
- Tape measure (ideally one that has centimeters and inches)
- Hardback book or ruler
This will work for road bikes and mountain bikes and can be measured in inches or centimeters. You can also choose your gender using the calculator to get an even more accurate assessment.
Step 1 – Measure Your Standing Position
This includes your inseam, total height, and sternal notch (the length from your collarbone area to the floor). To get your total height, you’ll stand against a wall while balancing a book on your head. Mark the wall where the bottom of the book meets it, then measure that distance from the floor. The sternal height is the measurement from your sternal notch (the indent between your collar bones) and the floor.
Step 2 – Measure Your Arms
This is where the marker comes in. To measure the lower part of your arms, you’ll want to hold a small cylindrical object perpendicular to your forearm. Measure from your elbow to the knuckles. To measure your upper arm, continue to hold the object and extend your arm out. Measure from the elbow to the shoulder. Do all of this for both arms and take the average.
Step 3 – Measure Your Seated Position
This process is a bit more involved as it requires measuring your upper legs, lower legs, and torso. Sit on a stool and measure your upper legs by balancing a level across the front of both kneecaps. Measure from the inside face of the straight edge to the wall.
For your lower legs, you’ll place that level where your kneecaps meet your quads. Take the measurement from the bottom of the level to the ground. To measure your torso, find the bony bump on the top of your shoulder and rest the level between that and the wall. Measure from the bottom of the level to the top of the stool
You can enter all of these measurements into the calculator. Their guide will also provide the details to make sure you’re measuring the correct spots.
Here is a video to further help you,
How Do I Know the Bike Is the Right Fit?
You’ll know your bike fits you well if you do not experience any significant pain and discomfort during the ride (aside from general training exertion). But there are a few key indicators you can measure to see if your bike is properly fitted.
Stand up with the frame of the bike straddled in between your legs and lift the bike. There should be about 1” worth of clearance between the tires and the ground.
Upper Body Position
An effective top tube position (ETT) is the distance between the head tube and the seat tube. Having this set up correctly will make for a much more comfortable ride. You’ll want your arms to have a slight bend to act as a shock absorber, but not so bent that you end up hunched over. Generally speaking, you’ll want to form a 45-degree angle between your torso and hip with your arms at a 90-degree angle.
Having the correct saddle height will give you optimal power with each pedal stroke. While sitting on your bike with your foot at the bottom of a pedal stroke, you should have only a slight bend to the knee (about 80-90% extended).
This is referred to as the fore/aft position. Sit on your bike and move your foot on the pedal to a 3 o’clock position. Your knee should be aligned directly with your forefoot.
To see all of the above-explained with visuals, check out this REI bike fitting video.
Is It Worth It to Get a Professional Bike Fitting?
Yes, if you can afford it. While a lot of these measurements can be done at home, nothing can really compare to the accuracy of a professional bike fitting. At-home measurements are subject to error, especially if you’re trying to do it without any help.
Check out our post The cost of bike fitting and what to expect (Amateur, advanced and professional)
Plan to spend up to two hours at the shop getting fitted. If you already own a bike, you can bring it in and have them help you fine-tune the componentry to fit your exact measurements and riding style.
In the market for a new bike? It may be best to visit a store that offers professional fittings so you know you’ll walk out with a perfect fit. The associates can also help you choose a saddle and footwear, but don’t be shy about sticking to your budget.
Is There a Difference Bike Criteria Based on Gender?
Historically, bikes have been designed to fit the average man. Women generally have narrower shoulders and longer legs relative to their torso length. Because of this, there have been a variety of women’s-specific bikes that have hit the market.
These include brands like Liv Cycling and Julianna. Many women find that traditional bikes fit them just fine.