When riding a road bike, it is essential that you have an appropriately sized frame to ensure your comfort and safety. If you ride a frame that is not the right size (too big or too small), it can be uncomfortable and make it difficult to handle and control the bike. You need to know your inseam measurements and total reach, and compare them to your frame size to make sure you're riding a road bike that fits your body well. Your best option is to go to a bike shop to take advantage of their professional fit system, which consists of taking body measurements and adapting the bike to achieve a perfect fit.
Method 1 of 3: Find the Right Frame Size
Step 1. Use your overall height and a road bike size chart as a basic guide
Stand against a wall, measure your overall height and record it in centimeters, as this is how road bike frames are measured. Through an internet search or borrowing a table from a bike store, determine the height of the bike that is associated with your overall height. Use the frame so you know if you need an extra small, small, medium, large or extra large bike.
- You can convert your height from inches to centimeters by multiplying it by 2.54.
- You shouldn't use height charts as the only resource for sizing a road bike, but they are a good starting point for determining the basic frame size to look for.
- Some boards are more specific, with up to 6 or 7 categories of bike frames.
Step 2. Measure your inseam with a tape measure
Space your feet 8 to 10 inches (20 to 25 cm) apart, as if you were on the bike. Then, place a book vertically between your legs, touching the crotch to simulate the seat of the bicycle. While holding the book in place with your hands, have a friend measure the distance from the top of the book to the floor and write these measurements down for you to use later.
- You should hold the book between your upper thighs, simulating the seat of a road bike.
- If you recorded your measurement in inches, you must multiply it by 2.54 to convert it to centimeters.
- You can take this measurement multiple times and record the average to get a more accurate value.
Step 3. Multiply your inseam measurement (in centimeters) by 0.67 to get a suggested size
This equation will yield the ideal vertical frame (or seat tube) size for you in centimeters. You are going to use this number to get a seat tube that adapts to your body. Write this number down in a notebook or your cell phone, as you will use it when you visit the bike shop or measure your current road bike.
- This formula will give you a suggested size, but not a guaranteed fit.
- Check your calculations and start over if you feel like you've made a mistake, as this value is essential for sizing a road bike.
- For example, if your inseam is 80 cm, your frame size will be approximately 54 cm.
Step 4. Measure the seat tube of the bike
Identify the top of the tube where the clamp holds the seat post. Find the center of the bottom bracket shell, which is where the axle meets the arms of the bike. Using a tape measure, measure the distance between these 2 points to determine the length of the seat tube. This distance should match your inseam measurement to get a frame of the right size.
This measurement is known as the C-T measurement and is used to determine the size of the box
Step 5. Compare your inseam measurement with the C-T measurement of the bike
Determine the correlation between the inseam measurement and the seat tube measurement and write it down. The difference between these measurements must be within 2.54 cm (1 inch) to achieve an appropriately sized painting.
- If you are buying a new road bike, you should choose a frame whose seat tube matches your crotch measurement.
- If you are measuring your current road bike, consider purchasing a new frame if the bike's seat tube measurement differs from your crotch.
Method 2 of 3: Get the Right Size Top Tube
Step 1. Measure the length of your torso
Use a tape measure and measure the distance from your hip to your shoulder. To get an accurate measurement, you should place a book between your legs vertically (simulating a bicycle seat) and measure from the top of the book to your collarbone. Measure this distance in inches and record the measurement on a piece of paper.
You can also record this distance by measuring from the hipbone to the top of the shoulder with a tape measure
Step 2. Record your arm's reach
Extend one arm so that it is parallel to the floor and measure the distance from the fingertips to the shoulder. To get a more accurate measurement, hold a pencil in your hand and measure the distance between the pencil and the collarbone.
Step 3. Determine your total reach using these measurements
To determine your total range, you must add these measurements and divide the sum by 2. Then add 4 inches (10 cm) to this value and record the sum on a piece of paper. You are going to use your full range to find the correct top tube measurement on a road bike.
This equation should look like this: [(torso length + arm distance) / 2] + 4 in. (10 cm) = total reach
Step 4. Find and measure the top tube of the road bike
Use a tape measure to find the distance between the head tube or the point where the frame connects to the bike's handlebars and the seat tube. This distance should almost match your total reach in order for you to get a road bike that fits your body comfortably.
- If the length of the top tube is longer than your full reach, then the bike frame is too big.
- If the length of the top tube is less than your full reach, try to get a larger frame that better fits your measurements.
- Another alternative to total frame replacement if the top tube is the wrong size may be to replace the handlebar stem with one that is longer or shorter, depending on what you need.
Method 3 of 3: Make adjustments to the bike
Step 1. Adjust the seat height for a more comfortable reach
If the length of the top tube almost matches your full reach, but you still feel uncomfortable on the bike, adjusting the seat will likely solve the problem. Use a wrench to loosen the bolt that connects the seat post to the seat tube. Use a bike rack or gate to support yourself. Your legs should be fully extended with the heel on the pedal. Raise or lower the seat and tighten the bolt again.
- Avoid tightening the bolt too much, as you could damage the seat post, especially if it is made of carbon.
- You should bend your knee slightly when pedaling.
- If you can't flex your knee when pedaling, then the seat is too high.
- You should make adjustments to the height of the seat until you feel comfortable and achieve a slight bend in the knee while driving.
Step 2. Level the seat
Support the bike against a wall or other flat surface and loosen the bolts under the seat. You can use a level to make small adjustments until the seat is level. A level seat will be able to support all your weight without forcing you to use the muscles of the back or torso, which gives you full mobility on the pedal and allows you to change your weight on the seat.
- If a level seat doesn't feel comfortable, you can tilt it up or down 3 degrees to help position your body.
- You can buy foam pads for your seat if you find it uncomfortable or difficult to handle for long periods of time.
Step 3. Raise or lower the handlebars
Your back should be at a 45-degree angle while riding, so you can injure yourself and cause pain if you have a handlebar that is too high or too low. The handlebar of the road bike should be between 2 and 10 cm (1 and 4 inches) lower than the seat of the average rider. You must loosen all the bolts on the stem cap to raise or lower the handlebar. Adjust the handlebar to your comfort level and then tighten the bolts.
- If your bike has a non-threaded stem, you may need to tighten the bolts to a certain torque in a specific sequence. If you are not sure, you can check with a bike shop.
- Most riders like to have the handlebars at the same height as the seat.
- The width of the handlebars should be similar to your shoulders, so consider buying a new set if it doesn't fit your body.
Step 4. Let a professional adjust your bike
If you are not comfortable making these adjustments yourself, you can visit a local bike shop to have a professional do it for you. Any bike shop will help you make adjustments to handlebar position, seat height, and make sure the frame is the correct size. You can ask questions and be honest with the professional about what is comfortable for you and what is not.
Make sure to call the bike shop ahead of time to make an appointment
- You can check if a bike fits you by doing a height test. You should place the bike on top of the top tube with your feet apart. Place your hands on the stem and saddle, and pull the bike until it reaches the pelvic bone. Then have a friend measure the space under the tires, which should be between 1 and 2 inches (2 to 5 cm).
- Some bike shops have a fit studio with equipment that can help you find the right one for you. However, this feature can be expensive.