Measuring whether a bike would be a good fit used to rely on the seat-post length or the top-tube height. As bikes have developed to include many more styles and shapes, measuring to ensure a complete fit has become more involved because manufacturers now change the lengths of other parts of the bike that used to be a uniform size. Despite these changes, using your inseam as a comparison for the bike's top-tube height is still the first step in fitting a bike.
Step 1
Straddle the top tube of the bike frame, standing in front of the seat rather than sitting on it.
Step 2
Measure from the ground to the top bar. The bicycling advice website Why Cycle notes to look for at least one inch of clearance if you're measuring a road bike and three inches for mountain bikes. So if you've got a 26-inch inseam, the top bar should be no more than 25 inches high for road bikes and 23 inches high for mountain bikes.
Step 3
Lift the bike up while straddling it and have a friend measure the distance from the bottom of the bike tire to the ground as an alternate method. Jim Foreman, writing on the Oklahoma Bicycle Society website, notes that one inch between the floor and tire equals 1/2 inch clearance over the tube.
Tips and Warnings
- Top tube height is only one aspect of fitting a bike. Remember to check out seat-post angle, seat height and position, leg extension, handlebar height and how far you have to lean forward to reach the handlebars, too. Note that your inseam measurement matters only for bikes with a top tube running straight across from the seat post to the handlebar post, and not for bikes where the frame curves down to the bottom of the frame.
Things You'll Need
- Measuring tape
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