Nothing takes away all the fun from biking like an ill-fitting bicycle. Getting the right size and fit should be your top priority when shopping for a bike. You don’t have to go to a bike shop to get the right bike fit. There are many ways to determine your fit in the comfort of your home. If you are an online shopper, knowing how to size a bike will save you a great deal.
We have put together the methods you can use to determine which size bicycle is ideal for you. Note that this is not uniform for all bicycles. Your height, riding style and of course what you prefer most determines the right size.
- Road Bike
Road Bike Frame Sizing
Measuring your height against road bike sizing chart
- Stand straight against a wall and have someone take your height measurement in centimeters
- Find your ideal bike height using the above figure against the bike size chart
|Rider’s height (in centimeters)||Proposed road bike size (in centimeters)|
Measuring your inseam length
- Hold a book vertically between your legs while standing straight against a wall
- Stretch your legs 6-inches apart
- Have someone measure from the floor to the top of the book (in centimeters)
- Your ideal seat tube length is the figure above multiplied by .67
- Visit the bike shop with the above number to find a seat tube that fits you
Seat tube length
- Find the top of the seat tube. This should be the point where the seat post and the clamp meet
- Take the distance between the above to the center of position where the axle holds the crank arms together
- For a proper bike frame size, this measurement should match what you got as your inseam length above
Note; Select a frame whose seat tube length matches your inseam length if buying a new bike. If you already own a road bike, the bike’s seat tube length should match your inseam length. If not, consider replacing it.
Right-sized top tube
Measuring your upper body
- Stand straight against a wall
- Have someone measure from your crotch to the hollow on your neck
- Stretch one arm parallel to the floor while standing straight
- Have someone measure your hands to the collarbone
Your total reach is calculated by getting the sum of your upper body length and the arm span measurement. Divide the results by two then add 4-inches.
The above figure gives the right top tube size for your road bike
- Hybrid Bikes
Hybrid bikes are normally measured using frame size. It is essential to know your height and inseam length beforehand to help with this sizing.
Use the same steps as road bike frame sizing but use the table below for your ideal frame size
|Rider’s height (in centimeters)||Proposed hybrid bike frame size (in centimeters)|
- Mountain Bikes
Mountain Bike Sizing Chart
The frame size of a mountain bike is usually measured in inches.
|Rider’s height (in inches)||Proposed mountain bike frame size (in inches)|
|6’4’’ and up||23’’ and up||XX-large|
Note that mountain bike framing uses the same steps for measuring inseam, seat tube and top tube length for road bikes. Ensure you convert the measurements to inches. To get the seat tube length for a C-C frame, multiply your inseam length by .65 instead of .67
Stand over test
This method is a general way to test whether the mountain bike is the right height
- Stand over the mountain bike with your legs over the top tube of your mountain bike
- Straddle the bike with your feet resting flat on the floor
- The right size mountain bike gives an allowance of about 2-inches between the top tube and your crotch
When in between sizes
If the mountain bike sizing puts you in between sizes, use the ape index method to get the right one. The ape index determines your right reach.
- Measure from your right fingertip to the left fingertip
- Minus your height from the above figure
- A positive ape index means you should go for the next largest bike size. If the ape index is negative, pick the smaller size of the two bikes
Adjusting your bicycle
Your legs should be almost straight when pedaling while sitting on your saddle. When cycling with the pedal at the lower level, your leg should be bent slightly. Only the tip of your toes should touch the floor while on the bike’s seat.
To adjust, loosen the bolt that holds the seat post. Swivel the seat up or down to match your inseam length then tighten the bolt.
For maximum comfort, your bike’s seat should be level. Your pelvis should be flat on the saddle. To adjust, move the sit either up or down to offer you a level placement for your pelvis. You should also adjust it such that you do not slide either backward or forward when on the seat.
The correct height handlebars ensure a comfortable ride without straining your back, wrist, and shoulders. The height varies based on the type of bike.
For the correct handlebars height on your road bike, the top of the saddle should be 1-2 inches higher than the handlebars.
For a mountain bike, the handlebars should be 1-4 inches below the top of the saddle.
For hybrid bikes, the top of the handlebars should be 1-2 inches higher than the top of the saddle.
If the above does not match your bike, you can adjust the handlebars height by;
- Loosening the bolt at the handlebar’s base using a wrench
- Adjust the handlebar either up or down to the right height
- Tighten the bolt using the wrench
You now have all you need to know about determining the right bicycle size for you. However, be sure to test the bike after picking one. The bike should feel comfortable when you sit on it. Also, ensure you are 100% satisfied before walking out of the bike shop.
Image source: Bike Radar