Bike Fitting and Frame Sizes

If the bike doesn’t fit, it won’t be comfortable. If you buy the wrong type of bike, it won’t do what you bought it for. Here are five types of bicycles, their sizes and instructions for finding the right fit.


These are the traditional racing bikes where the seat is high off the ground and the handlebars lower than the seat, throwing the rider forward and down in an aerodynamic position. Road cycling bikes are sized according to the length of the seat tube; the metal tube that runs from the seat to the sprocket. They are measured in centimeters and range from 46 cm to 63 cm. Measure the length of your leg and subtract 25 centimeters. The bike should be big enough that your leg when almost fully extended reaches the pedal. Also, straddle the bike. Your feet should be flat on the ground without touching the cross bar with your pants.

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Mountain Bikes

Mountain bikes look like regular bikes but with very wide tires. The handlebars are higher than the seat. A mountain bike should be two to five inches shorter than the distance from the in-seam of your pants to the ground. Mountain bikes sizes are based on the seat tube length and are measured in inches. The riding position is more neutral than a road bike to allow the rider to navigate steep hills.

Cruiser Bikes

Cruiser bikes look like regular bikes. The rider sits very upright. They’re made for light, leisure riding and may be capable of carrying small items. The cruiser bike may also come with full fenders for riding in the rain. They come in small or an inseam measurement of 27 to 29 inches, medium or an inseam size of 29 to 32 inches, large or an inseam measurement of 32 to 34 inches and extra large or an inseam measurement of 34 to 37 inches.

BMX Bikes

These are built for competition in BMX sponsored contests held on concrete, speed tracks and dirt. The measurement for the BMX bike isn’t as important as the distance between the handbars and the pedals since the rider seldom, if ever, sits down while racing. The only way to find the right size is by a test run done by the individual rider.

Children’s Bikes

Take the child to the bicycle store. Have them straddle the bike. Their feet should be flat on the floor and the crossbar shouldn’t touch their pants and the handlebars shouldn’t be higher than their shoulders.

Measuring the Rider

Measuring an inseam is always a delicate matter, yet this is the measurement you have to have to buy a bike. You can’t do it yourself, and it’s awkward to ask someone else to do it. Here’s the answer. Place a book between your legs as high up as it will go. Have someone else measure from the top of the book to the ground. That’s your leg length or inseam measurement.

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